Protection of "iron" from corrosion is carried out in several cases: during primary processing, in order to restore damage in a separate area or decorate a sample. In this case, various metals are used - brass, copper, silver and a number of others. We will deal with nickel plating technology at home as one of the simplest and most affordable in terms of self-implementation.

In addition, it is also the most common. When coating parts protective layer of other metals, the thinnest film of nickel plays the role of an intermediate. It is advisable to apply it, for example, before.

Note. There are quite a few recipes for the chemicals used. The author considered it right to cite only those whose effectiveness he was personally convinced of by applying a protective nickel coating at home.

The unit of measurement of the components is g/l of water (unless otherwise specified). All chemicals used are diluted separately, carefully filtered and only then mixed to obtain an electrolytic solution.

Preparation of samples for nickel plating

All activities are not only identical, but also mandatory, regardless of the chosen technology for applying a protective (decorative) layer.

Sandblasting

The goal is to remove rust, oxides (pickling) and other foreign layers as much as possible. You can read an article on how to make at home, from improvised materials. For example, remake the spray gun.

Compositions for decapitation

No. 1. Sulfuric (concentrated) acid (75 g) + chromic (3 g) in half a glass of water. The holding time of the part in the solution is about 20 seconds.

No. 2. Sulfuric acid (hydrochloric) 5 g + water (half a glass). Processing time - up to 1 min.

Grinding

Such careful leveling helps to obtain a uniform nickel layer and reduces the consumption of the prepared solution. Depending on the significance of the defects (the size of the gaps, scratches), sandpaper with different grain sizes, kartsovochny brushes, grinding pastes are used.

Degreasing

Previously, after grinding, the sample is washed under running water to remove all adhering fractions. What to use (alcohol, gasoline, white spirit or a specially prepared solution) is decided on the spot. The main condition is that the solvent must be “compatible” with the base material being nickel-plated.

In particularly difficult cases, if commercially available solvents do not help, it is advisable to prepare preparations for degreasing yourself.

Recipes for aqueous solutions for steel and cast iron

No. 1. Caustic soda (10 - 15) + "liquid glass" (10) + soda ash (50).

No. 2. Caustic soda (50) + sodium phosphate and soda ash (30 each) + "liquid glass" (5).

non-ferrous metals

No. 1. Sodium phosphate + laundry soap(for 10 - 15).

No. 2. Caustic soda (10) + sodium phosphate (50 - 55).

• To check the quality of degreasing, it is enough to moisten the sample with water. If it covers the surface with the thinnest film, without the formation of drops, this indicates that the goal of the technological operation has been achieved and the part is ready for nickel plating.
• The working temperature of the solutions is within + (65 - 85) ºС.

Nickel plating technologies

Nickel plating electrolytic

The simplest schemes for home use are shown in the figure.

• Vessel (1) - any convenient shape and capacity. The only requirement is that the material must be chemically neutral with respect to the electrolyte used. Most often at home, glass containers are used for nickel plating.
• Anodes (2) are nickel. In order for the coating of the sample to be uniform, homogeneous, they must be on different sides of the workpiece. Therefore, at least 2.
• Detail (3). It is also the cathode. It is hung out so that it does not touch the walls and bottom of the container.

Connections: plus source - with plates, minus - with the sample.

The composition of the solution for nickel plating: sulfate sodium (50), nickel (140), magnesium (30) + boric acid (20) + table salt (5).

Nickel plating conditions: temperature +22 (±2) ºС, current density - within 1 (±0.2) A/dm².

Nickel plating technology. The power is turned on and the required current value is set. The process lasts from 20 minutes to half an hour. The degree of readiness of the part is determined visually, by the shade (grayish-matte) and its uniformity.

With a deficiency (absence) of some components at home, you can prepare a composition with a limited number of ingredients by increasing their proportion per liter of water.

Nickel sulfate (250) - sodium chloride (25) - boric acid (30). But with such an electrolyte composition, nickel plating conditions change. The solution is heated to approximately +55 ºС (in order to activate the process, as with), and the current density increases to 4 - 5.

What to consider

• The quality of nickel plating largely depends on the acidity of the solution. It is checked by staining litmus paper - the color should be red. If it is necessary to lower the acidity value, an ammonia solution can be introduced into the electrolyte. The dosage is determined independently; reference point - the shade of the litmus "indicator".
• The electrolytic method of nickel plating is not always effective. If the sample surface is complex relief, then the coating will lie unevenly, and in particularly problematic areas it may not be at all. For example, in grooves, slots, holes and so on.

Nickel plating chemical

The technology is much simpler, since all that is needed is porcelain (enamelled dishes). At the same time, the quality is higher, since there will be no untreated areas left. All components are dissolved in water, after which the solution is heated to a temperature of approximately + (85 - 90) ºС. And after that, regardless of the recipe used, sodium hypophosphite is introduced into it (let's denote NG).

After mixing, you can start nickel plating. It consists in the fact that the part is suspended so that it is completely immersed in the chemical / reagent. Quality control is the same - visually.

There are quite a few compositions for chemical nickel plating. Here are some recipes:

No. 1. Sulphate ammonium and nickel (30 each) - temperature increase - NG (10). The required acidity is about 8.5.

No. 2. Nickel chloride (30) + glycolic acid (40) - heating - NG 10 (acidity 4.2 - 4.4).

No. 3. Sodium citrate, ammonium chloride and nickel chloride (45 each) - heating - NG (20; 8.5).

Recommendation - with acidic solutions (pH less than 6.5) it is better to process products made of copper, ferrous metals (alloys), brass. This results in a layer that is close to perfectly smooth. Alkaline compositions (pH from 6.5 and above) are used, as a rule, for nickel plating of stainless steel products. Such a coating is characterized by high-quality adhesion to the base.

Nickel plating

It is advisable to practice when processing large-sized workpieces, for which at home it is problematic or impossible to select a container of the desired size. The technique itself is simple, since galvanic processes are excluded with it. The difficulty is different - you have to spend a lot of time to prepare necessary equipment and accessories. First of all, a brush.

The composition of the scheme:

Continuously adjustable DC source within 5 - 15 V (up to 2 A). It makes no sense to purchase it specifically for nickel plating, since it is made independently for a person who has completed high school, will not be difficult. You will need a TR with an appropriate secondary winding and a rectifier (bridge). Diodes of the 303 - 305 series are quite suitable.

Brush. A diameter of 25 (±) mm is sufficient. Its handle must be made of dielectric. If you focus on what is in the house, then best option- make a piece of PP or PE pipe. From one end, the handle is “suppressed” by a lid. As the bristles, a pile is used, for example, from synthetics.

The villi are collected in a bundle, the upper part of which is wrapped with wire (stainless steel), under which a curved nickel plate is placed. It turns out an analogue of a paint brush. This is the anode of the circuit. The minus of the source is connected to the workpiece.

Wires. Enough for 0.5 "square". In the garage, any owner will always find suitable pieces.

The formulation of the composition

• Sulphate sodium and nickel - 40 and 70.
• Boric acid - 20.
• Sodium chloride - 5.

Note. For nickel plating using this technology, you can use the same solution as using the electrolytic method (clause 2.1.3.)

Nickel plating procedure: the prepared electrolyte is poured into the handle, voltage is applied, and the brush moves systematically, with a clamp, over the part. The inconvenience is that you will have to constantly monitor the level of the solution in the handle and top up regularly. But if at home you want to cover something voluminous with nickel, for example, a car bumper, rims, then there is simply no other option.

Recommendation - to simplify the process of preparing the equipment, a nickel plate can be used instead of a brush. She plays the role of an anode. It must be wrapped in a piece of flannel with a thickness of at least 4 mm, and a container with electrolyte should be placed next to the workpiece. The technology is simple - constantly wetting such an impromptu electrode in a solution, drive it over the surface of the sample. The effect is the same, and the result depends entirely on the diligence and accuracy of the home master.

Final processing of parts

• Drying. If the sample has a complex relief, then you need to make sure that there is no moisture in all problem areas (grooves, recesses, and so on).
• Surface sealing. Nickel film is characterized by porosity, even if the coating is done in several layers. Therefore, direct contact of the base with the liquid cannot be avoided. It's just a matter of time. The result is corrosion and nickel flaking.

How can you seal the pores at home:

• A somewhat exotic but effective way is to immerse a still warm sample in fish oil.
• Mix magnesium oxide with water, bring to a state of thick sour cream and rub the nickel-plated part with such a “slurry” and lower it for a couple of minutes in a solution (50%) of hydrochloric acid.
• Treat the surface with a transparent lubricant capable of penetrating deep into the structure, in 2-3 passes.

Excess drugs (not earlier than after 24 hours) are easily washed off with gasoline.

Polishing

At this stage, the nickel-plated workpiece is given a specific sheen.

Helpful information

Not every "iron" is subjected to nickel plating. This treatment does not apply to tin, lead and other metals and alloys less common in everyday life.

For better nickel plating, it is desirable to make a preliminary copper plating of the workpiece. There are two main reasons.

The first is already indicated - the porosity of the coating.

The second is that with copper, the nickel layer is bonded much more reliably than with any alloy or pure steel. Consequently, the nickel-plated part will retain an unchanged attractive appearance much longer. If it is possible to make a copper plating of a sample at home, then this is the best solution to the problem.

The composition of the electrolyte for coating a steel part with a copper film

Copper sulfate (200) + sulfuric acid, concentrated (50). Sample processing conditions: current density - 1.5A/dm²; temperature - room +22 (±2) ºС.

When conducting nickel plating at home, you can focus on such data - 1 liter of electrolyte is enough to process the part with total area no more than 2 dm². Based on this, the required amount of solution is determined.

Information for action
(technology tips)
Erlykin L.A. DIY 3-92

Before any of the home craftsmen did not get up the need to nickel or chrome this or that part. What do-it-yourselfer did not dream of installing a “non-working” bushing with a hard, wear-resistant surface obtained by saturating it with boron in a critical node. But how to do at home what, as a rule, is carried out at specialized enterprises using the methods of chemical-thermal and electrochemical processing metals. You will not build gas and vacuum furnaces at home, or build electrolysis baths. But it turns out that it is not necessary to build all this at all. It is enough to have some reagents on hand, an enamel pan and, perhaps, a blowtorch, and also know the recipes " chemical technology”, with the help of which metals can also be copper-plated, cadmium-plated, tinned, oxidized, etc.

So, let's start getting acquainted with the secrets of chemical technology. Please note that the content of the components in the solutions given, as a rule, are given in g / l. If other units are used, a special clause follows.

Preparatory operations

Before applying paints, protective and decorative films to metal surfaces, as well as before coating them with other metals, it is necessary to carry out preparatory operations, that is, to remove pollution of various nature from these surfaces. Please note that the final result of all work depends to a large extent on the quality of the preparatory operations.

Preparatory operations include degreasing, cleaning and pickling.

Degreasing

The process of degreasing the surface of metal parts is carried out, as a rule, when these parts have just been processed (ground or polished) and there are no rust, scale and other foreign products on their surface.

With the help of degreasing, oil and grease films are removed from the surface of the parts. For this, aqueous solutions of some chemicals are used, although organic solvents can also be used for this. The latter have the advantage that they do not have a subsequent corrosive effect on the surface of the parts, but they are toxic and flammable.

aqueous solutions. Degreasing of metal parts in aqueous solutions is carried out in enameled dishes. Pour water, dissolve chemicals in it and put on a small fire. When the desired temperature is reached, the parts are loaded into the solution. During processing, the solution is stirred. Below are the compositions of the degreasing solutions (g/l), as well as the operating temperatures of the solutions and the processing time of the parts.

Compositions of degreasing solutions (g/l)

For ferrous metals (iron and iron alloys)

Liquid glass (stationery silicate glue) - 3 ... 10, caustic soda (potassium) - 20 ... 30, trisodium phosphate - 25 ... 30. Solution temperature - 70...90°C, processing time - 10...30 min.

Liquid glass - 5 ... 10, caustic soda - 100 ... 150, soda ash - 30 ... 60. Solution temperature - 70...80°C, processing time - 5...10 min.

Liquid glass - 35, trisodium phosphate - 3 ... 10. Solution temperature - 70...90°С, processing time - 10...20 min.

Liquid glass - 35, trisodium phosphate - 15, preparation - emulsifier OP-7 (or OP-10) -2. Solution temperature - 60-70°С, processing time - 5...10 min.

Liquid glass - 15, preparation OP-7 (or OP-10) -1. Solution temperature - 70...80°С, processing time - 10...15 min.

Soda ash - 20, potassium chromium peak - 1. Solution temperature - 80 ... 90 ° C, processing time - 10 ... 20 minutes.

Soda ash - 5 ... 10, trisodium phosphate - 5 ... 10, preparation OP-7 (or OP-10) - 3. Solution temperature - 60 ... 80 ° C, processing time - 5 ... 10 min .

For copper and copper alloys

Caustic soda - 35, soda ash - 60, trisodium phosphate - 15, preparation OP-7 (or OP-10) - 5. Solution temperature - 60 ... 70, processing time - 10 ... 20 minutes.

Caustic soda (potassium) - 75, liquid glass - 20 Solution temperature - 80 ... 90 ° C, processing time - 40 ... 60 minutes.

Liquid glass - 10 ... 20, trisodium phosphate - 100. Solution temperature - 65 ... 80 C, processing time - 10 ... 60 minutes.

Liquid glass - 5 ... 10, soda ash - 20 ... 25, preparation OP-7 (or OP-10) - 5 ... 10. Solution temperature - 60...70°С, processing time - 5...10 min.

Trisodium phosphate - 80...100. Solution temperature - 80...90°С, processing time - 30...40 min.

For aluminum and its alloys

Liquid glass - 25...50, soda ash - 5...10, trisodium phosphate-5...10, preparation OP-7 (or OP-10) - 15...20 min.

Liquid glass - 20 ... 30, soda ash - 50 ... 60, trisodium phosphate - 50 ... 60. Solution temperature - 50…60°С, processing time - 3...5 min.

Soda ash - 20 ... 25, trisodium phosphate - 20 ... 25, preparation OP-7 (or OP-10) - 5 ... 7. Temperature - 70...80°С, processing time - 10...20 min.

For silver, nickel and their alloys

Liquid glass - 50, soda ash - 20, trisodium phosphate - 20, preparation OP-7 (or OP-10) - 2. Solution temperature - 70 ... 80 ° C, processing time - 5 ... 10 minutes.

Liquid glass - 25, soda ash - 5, trisodium phosphate - 10. Solution temperature - 75 ... 85 ° C, processing time - 15 ... 20 minutes.

For zinc

Liquid glass - 20 ... 25, caustic soda - 20 ... 25, soda ash - 20 ... 25. Solution temperature - 65...75°С, processing time - 5 min.

Liquid glass - 30...50, soda ash - 30..,50, kerosene - 30...50, preparation OP-7 (or OP-10) - 2...3. Solution temperature - 60-70°С, processing time - 1...2 min.

organic solvents

The most commonly used organic solvents are B-70 gasoline (or "lighter gasoline") and acetone. However, they have a significant drawback - they are easily flammable. Therefore, they have recently been replaced by non-flammable solvents such as trichlorethylene and perchlorethylene. Their dissolving power is much higher than that of gasoline and acetone. Moreover, these solvents can be fearlessly heated, which greatly accelerates the degreasing of metal parts.

Degreasing the surface of metal parts with organic solvents is carried out in the following sequence. The parts are loaded into a container with a solvent and incubated for 15 ... 20 minutes. Then the surface of the parts is wiped directly in the solvent with a brush. After such treatment, the surface of each part is carefully treated with a swab moistened with 25% ammonia (it is necessary to work with rubber gloves!).

All degreasing work organic solvents carried out in a well-ventilated area.

cleaning

In this section, as an example, the decarbonization process of internal combustion engines will be considered. As you know, carbon deposits are asphalt-resinous substances that form hard-to-remove films on the working surfaces of engines. Removing carbon deposits is a rather difficult task, since the carbon film is inert and firmly adhered to the surface of the part.

Compositions of cleaning solutions (g/l)

For ferrous metals

Liquid glass - 1.5, soda ash - 33, caustic soda - 25, laundry soap - 8.5. Solution temperature - 80...90°C, processing time - Zh.

Caustic soda - 100, potassium dichromate - 5. Solution temperature - 80 ... 95 ° C, processing time - up to 3 hours.

Caustic soda - 25, liquid glass - 10, sodium bichromate - 5, laundry soap - 8, soda ash - 30. Solution temperature - 80 ... 95 ° C, processing time - up to 3 hours.

Caustic soda - 25, liquid glass - 10, laundry soap - 10, potash - 30. Solution temperature - 100 ° C, processing time - up to 6 hours.

For aluminum (duralumin) alloys

Liquid glass 8.5, laundry soap - 10, soda ash - 18.5. Solution temperature - 85...95 C, processing time - up to 3 hours.

Liquid glass - 8, potassium dichromate - 5, laundry soap - 10, soda ash - 20. Solution temperature - 85 ... 95 ° C, processing time - up to 3 hours.

Soda ash - 10, potassium dichromate - 5, laundry soap - 10. Solution temperature - 80 ... 95 ° C, processing time - up to 3 hours.

Etching

Etching (as a preparatory operation) allows you to remove contaminants (rust, scale and other corrosion products) firmly adhered to their surface from metal parts.

The main purpose of etching is the removal of corrosion products; while the base metal should not be etched. To prevent metal etching, special additives are introduced into the solutions. Good results are obtained by the use of small amounts of hexamethylenetetramine (urotropine). In all solutions for etching ferrous metals, add 1 tablet (0.5 g) of urotropine per 1 liter of solution. In the absence of urotropin, it is replaced with the same amount of dry alcohol (sold in sports stores as fuel for tourists).

Due to the fact that recipes for etching use inorganic acids, you need to know their initial density (g / cm 3): nitric acid - 1.4, sulfuric acid - 1.84; hydrochloric acid - 1.19; phosphoric acid - 1.7; acetic acid - 1.05.

Compositions of solutions for etching

For ferrous metals

Sulfuric acid - 90...130, hydrochloric acid - 80...100. Solution temperature - 30...40°С, processing time - 0.5...1.0 h.

Sulfuric acid - 150...200. Solution temperature - 25...60°С, processing time - 0.5...1.0 h.

Hydrochloric acid - 200. Solution temperature - 30...35°С, processing time - 15...20 min.

Hydrochloric acid - 150 ... 200, formalin - 40 ... 50. Solution temperature 30...50°C, treatment time 15...25 min.

Nitric acid - 70...80, hydrochloric acid - 500...550. Solution temperature - 50°С, processing time - 3...5 min.

Nitric acid - 100, sulfuric acid - 50, hydrochloric acid - 150. Solution temperature - 85°C, processing time - 3...10 min.

Hydrochloric acid - 150, phosphoric acid - 100. Solution temperature - 50°C, processing time - 10...20 min.

The last solution (when processing steel parts), in addition to cleaning the surface, also phosphates it. And phosphate films on the surface of steel parts make it possible to paint them with any paint without a primer, since these films themselves serve as an excellent primer.

Here are a few more recipes for etching solutions, the compositions of which this time are given in% (by weight).

Orthophosphoric acid - 10, butyl alcohol - 83, water - 7. Solution temperature - 50...70°C, processing time - 20...30 min.

Orthophosphoric acid - 35, butyl alcohol - 5, water - 60. Solution temperature - 40...60°C, processing time - 30...35 min.

After etching of ferrous metals, they are washed in a 15% solution of soda ash (or drinking) soda. Then rinse thoroughly with water.

Note that below the compositions of the solutions are again given in g/L.

For copper and its alloys

Sulfuric acid - 25...40, chromic anhydride - 150...200. Solution temperature - 25°С, processing time - 5...10 min.

Sulfuric acid - 150, potassium bichromate - 50. Solution temperature - 25.35°C, processing time - 5...15 min.

Trilon B-100. Solution temperature - 18...25°C, processing time - 5...10 min.

Chromic anhydride - 350, sodium chloride - 50. Solution temperature - 18...25°С, processing time - 5...15 min.

For aluminum and its alloys

Caustic soda -50...100. Solution temperature - 40...60°С, treatment time - 5...10 s.

Nitric acid - 35...40. Solution temperature - 18...25°С, treatment time - 3...5 s.

Caustic soda - 25 ... 35, soda ash - 20 ... 30. Solution temperature - 40...60°С, treatment time - 0.5...2.0 min.

Caustic soda - 150, sodium chloride - 30. Solution temperature - 60°C, processing time - 15 ... 20 s.

Chemical polishing

Chemical polishing allows you to quickly and efficiently process the surface of metal parts. The great advantage of this technology is that with the help of it (and only it!) It is possible to polish parts with a complex profile at home.

Compositions of solutions for chemical polishing

For carbon steels (the content of components is indicated in each case in certain units (g / l, percent, parts)

Nitric acid - 2.-.4, hydrochloric acid 2 ... 5, Orthophosphoric acid - 15 ... 25, the rest is water. Solution temperature - 70...80°С, processing time - 1...10 min. The content of the components - in% (by volume).

Sulfuric acid - 0.1, acetic acid - 25, hydrogen peroxide (30%) - 13. Solution temperature - 18 ... 25 ° C, processing time - 30 ... 60 minutes. Content of components - in g/l.

Nitric acid - 100...200, sulfuric acid - 200..,600, hydrochloric acid - 25, Orthophosphoric acid - 400. Mixture temperature - 80...120°С, treatment time - 10...60 s. Content of components in parts (by volume).

For stainless steel

Sulfuric acid - 230, hydrochloric acid - 660, acid orange dye - 25. Solution temperature - 70...75°С, processing time - 2...3 min. Content of components - in g/l.

Nitric acid - 4 ... 5, hydrochloric acid - 3 ... 4, Orthophosphoric acid - 20..30, methyl orange - 1..1.5, the rest is water. Solution temperature - 18...25°С, treatment time - 5..10 min. The content of the components - in% (by weight).

Nitric acid - 30...90, potassium ferricyanide (yellow blood salt) - 2...15 g/l, preparation OP-7 - 3...25, hydrochloric acid - 45..110, phosphoric acid - 45. ..280.

Solution temperature - 30...40°С, processing time - 15...30 min. The content of components (except for yellow blood salt) - in pl / l.

The latter composition is applicable for polishing cast iron and any steels.

For copper

Nitric acid - 900, sodium chloride - 5, soot - 5. Solution temperature - 18 ... 25 ° C, processing time - 15 ... 20 s. Content of components - g/l.

Attention! Sodium chloride is added to solutions last, and the solution must be pre-cooled!

Nitric acid - 20, sulfuric acid - 80, hydrochloric acid - 1, chromic anhydride - 50. Solution temperature - 13..18°C, processing time - 1...2 min. Content of components - in ml.

Nitric acid 500, sulfuric acid - 250, sodium chloride - 10. Solution temperature - 18 ... 25 ° C, processing time - 10 ... 20 s. Content of components - in g/l.

For brass

Nitric acid - 20, hydrochloric acid - 0.01, acetic acid - 40, phosphoric acid - 40. Mixture temperature - 25...30°C, processing time - 20...60 s. Content of components - in ml.

Sulphate copper ( blue vitriol) - 8, sodium chloride - 16, acetic acid - 3, water - the rest. Solution temperature - 20°С, processing time - 20...60 min. The content of components - in% (by weight).

For bronze

Orthophosphoric acid - 77 ... 79, potassium nitrate - 21 ... 23. Mixture temperature - 18°C, processing time - 0.5-3 min. The content of components - in% (by weight).

Nitric acid - 65, sodium chloride - 1 g, acetic acid - 5, orthophosphoric acid - 30, water - 5. Solution temperature - 18 ... 25 ° C, processing time - 1 ... 5 s. The content of components (except sodium chloride) - in ml.

For nickel and its alloys (cupronickel and nickel silver)

Nitric acid - 20, acetic acid - 40, phosphoric acid - 40. Mixture temperature - 20°C, processing time - up to 2 minutes. The content of components - in% (by weight).

Nitric acid - 30, acetic acid (glacial) - 70. Mixture temperature - 70...80°С, treatment time - 2...3 s. The content of components - in% (by volume).

For aluminum and its alloys

Orthophosphoric acid - 75, sulfuric acid - 25. Mixture temperature - 100°C, processing time - 5...10 min. The content of components - in parts (by volume).

Orthophosphoric acid - 60, sulfuric acid - 200, nitric acid - 150, urea - 5g. The temperature of the mixture is 100°C, the processing time is 20 s. The content of components (except urea) - in ml.

Orthophosphoric acid - 70, sulfuric acid - 22, boric acid - 8. Mixture temperature - 95°C, processing time - 5...7 min. The content of components - in parts (by volume).

Passivation

Passivation is the process of chemically creating an inert layer on the surface of a metal, which prevents the metal itself from oxidizing. The process of passivating the surface of metal products is used by chasers when creating their works; craftsmen - in the manufacture of various crafts (chandeliers, sconces and other household items); sports anglers passivate their homemade metal lures.

Compositions of solutions for passivation (g/l)

For ferrous metals

Sodium nitrite - 40...100. Solution temperature - 30...40°С, processing time - 15...20 min.

Sodium nitrite - 10...15, soda ash - 3...7. Solution temperature - 70...80°С, processing time - 2...3 min.

Sodium nitrite - 2...3, soda ash - 10, preparation OP-7 - 1...2. Solution temperature - 40...60°С, processing time - 10...15 min.

Chromic anhydride - 50. Solution temperature - 65 ... 75 "C, processing time - 10 ... 20 minutes.

For copper and its alloys

Sulfuric acid - 15, potassium dichromate - 100. Solution temperature - 45°C, processing time - 5...10 min.

Potassium dichromate - 150. Solution temperature - 60°C, processing time - 2...5 min.

For aluminum and its alloys

Orthophosphoric acid - 300, chromic anhydride - 15. Solution temperature - 18...25°C, processing time - 2...5 min.

Potassium dichromate - 200. Solution temperature - 20°C, "treatment time -5...10 min.

For silver

Potassium dichromate - 50. Solution temperature - 25 ... 40 ° C, processing time - 20 minutes.

For zinc

Sulfuric acid - 2...3, chromic anhydride - 150...200. Solution temperature - 20°С, processing time - 5...10 s.

Phosphating

As already mentioned, the phosphate film on the surface of steel parts is a fairly reliable anti-corrosion coating. It is also an excellent primer for paintwork.

Some low-temperature phosphating methods are applicable to bodywork cars before coating them with anti-corrosion and anti-wear compounds.

Compositions of solutions for phosphating (g/l)

For steel

Mazhef (phosphate salts of manganese and iron) - 30, zinc nitrate - 40, sodium fluoride - 10. Solution temperature - 20 ° C, processing time - 40 minutes.

Monozinc phosphate - 75, zinc nitrate - 400 ... 600. Solution temperature - 20°С, processing time - 20...30 s.

Majef - 25, zinc nitrate - 35, sodium nitrite - 3. Solution temperature - 20°C, processing time - 40 min.

Monoammonium phosphate - 300. Solution temperature - 60 ... 80 ° C, processing time - 20 ... 30 s.

Phosphoric acid - 60...80, chromic anhydride - 100...150. Solution temperature - 50...60°С, processing time - 20...30 min.

Orthophosphoric acid - 400 ... 550, butyl alcohol - 30. Solution temperature - 50 ° C, processing time - 20 minutes.

Application metal coatings

The chemical coating of some metals with others impresses with the simplicity of the technological process. Indeed, if, for example, it is necessary to chemically nickel plate some steel part, it is enough to have suitable enameled dishes, a heating source ( gas stove, primus, etc.) and relatively non-deficient chemicals. An hour or two - and the part is covered with a shiny layer of nickel.

Note that only with the help of chemical nickel plating it is possible to reliably nickel-plating parts complex profile, internal cavities (pipes, etc.). True, chemical nickel plating (and some other similar processes) is not without its drawbacks. The main one is not too strong adhesion of the nickel film to the base metal. However, this drawback can be eliminated; for this, the so-called low-temperature diffusion method is used. It allows you to significantly increase the adhesion of the nickel film to the base metal. This method is applicable to all chemical coatings of some metals by others.

nickel plating

The process of chemical nickel plating is based on the reaction of nickel reduction from aqueous solutions its salts using sodium hypophosphite and some other chemicals.

Nickel coatings obtained by chemical means have an amorphous structure. The presence of phosphorus in nickel makes the film close in hardness to a chromium film. Unfortunately, the adhesion of the nickel film to the base metal is relatively low. Heat treatment of nickel films (low-temperature diffusion) consists in heating nickel-plated parts to a temperature of 400°C and holding them at this temperature for 1 hour.

If nickel-plated parts are hardened (springs, knives, fish hooks, etc.), then at a temperature of 40 ° C they can be released, that is, they can lose their main quality - hardness. In this case, low-temperature diffusion is carried out at a temperature of 270...300 C with an exposure of up to 3 hours. In this case, the heat treatment also increases the hardness of the nickel coating.

All the listed advantages of chemical nickel plating did not escape the attention of technologists. They found them practical use(except for the use of decorative and anti-corrosion properties). So, with the help of chemical nickel plating, the axes of various mechanisms, worms of thread-cutting machines, etc. are repaired.

At home, with the help of nickel plating (of course, chemical!) You can repair parts of various household devices. The technology here is extremely simple. For example, the axis of a device was demolished. Then they build up (with excess) a layer of nickel on the damaged area. Then the working section of the axis is polished, bringing it to the desired size.

It should be noted that chemical nickel plating cannot cover metals such as tin, lead, cadmium, zinc, bismuth and antimony.
Solutions used for chemical nickel plating are divided into acidic (pH - 4 ... 6.5) and alkaline (pH - above 6.5). Acidic solutions are preferably used for coating ferrous metals, copper and brass. Alkaline - for stainless steels.

Acidic solutions (compared to alkaline ones) on a polished part give a smoother (mirror-like) surface, they have less porosity, and the speed of the process is higher. Another important feature of acidic solutions is that they are less likely to self-discharge when the operating temperature is exceeded. (Self-discharge - instantaneous precipitation of nickel into a solution with splashing of the latter.)

In alkaline solutions, the main advantage is a more reliable adhesion of the nickel film to the base metal.

And the last. Water for nickel plating (and when applying other coatings) is taken distilled (you can use condensate from household refrigerators). Chemical reagents are suitable at least pure (designation on the label - H).

Before coating parts with any metal film, it is necessary to conduct a special preparation of their surface.

Preparation of all metals and alloys is as follows. The treated part is degreased in one of the aqueous solutions, and then the part is decapitated in one of the solutions listed below.

Compositions of solutions for decapitation (g/l)

For steel

Sulfuric acid - 30...50. Solution temperature - 20°С, processing time - 20...60 s.

Hydrochloric acid - 20...45. Solution temperature - 20°С, treatment time - 15...40 s.

Sulfuric acid - 50...80, hydrochloric acid - 20...30. Solution temperature - 20°С, processing time - 8...10 s.

For copper and its alloys

Sulfuric acid - 5% solution. Temperature - 20°C, processing time - 20s.

For aluminum and its alloys

Nitric acid. (Attention, 10 ... 15% solution.) Solution temperature - 20 ° C, processing time - 5 ... 15 s.

Please note that for aluminum and its alloys, before chemical nickel plating, one more treatment is carried out - the so-called zincate. Below are solutions for zincate treatment.

For aluminum

Caustic soda - 250, zinc oxide - 55. Solution temperature - 20 C, treatment time - 3 ... 5s.

Caustic soda - 120, zinc sulfate - 40. Solution temperature - 20 ° C, processing time - 1.5 ... 2 minutes.

When preparing both solutions, first, caustic soda is dissolved separately in half of the water, and the zinc component in the other half. Then both solutions are poured together.

For foundries aluminum alloys

Caustic soda - 10, zinc oxide - 5, Rochelle salt (crystal hydrate) - 10. Solution temperature - 20 C, processing time - 2 minutes.

For wrought aluminum alloys

Ferric chloride (crystal hydrate) - 1, sodium hydroxide - 525, zinc oxide 100, Rochelle salt - 10. Solution temperature - 25 ° C, processing time - 30 ... 60 s.

After zincate treatment, the parts are washed in water and hung in a nickel plating solution.

All solutions for nickel plating are universal, that is, they are suitable for all metals (although there are some specifics). Prepare them in a certain sequence. So, all chemicals (except sodium hypophosphite) are dissolved in water (enamelled dishes!). Then the solution is heated to the operating temperature and only after that sodium hypophosphite is dissolved and the parts are hung into the solution.

In 1 liter of solution, a surface up to 2 dm2 in area can be nickel plated.

Compositions of solutions for nickel plating (g/l)

Nickel sulphate - 25, sodium succinic acid - 15, sodium hypophosphite - 30. Solution temperature - 90°C, pH - 4.5, film growth rate - 15...20 µm/h.

Nickel chloride - 25, sodium succinic acid - 15, sodium hypophosphite - 30. Solution temperature - 90 ... 92 ° C, pH - 5.5, growth rate - 18 ... 25 μm / h.

Nickel chloride - 30, glycolic acid - 39, sodium hypophosphite - 10. Solution temperature 85..89°С, pH - 4.2, growth rate - 15...20 µm/h.

Nickel chloride - 21, sodium acetate - 10, sodium hypophosphite - 24, Solution temperature - 97 ° C, pH - 5.2, growth rate - up to 60 μm / h.

Nickel sulfate - 21, sodium acetate - 10, lead sulfide - 20, sodium hypophosphite - 24. Solution temperature - 90 ° C, pH - 5, growth rate - up to 90 μm / h.

Nickel chloride - 30, acetic acid - 15, lead sulfide - 10 ... 15, sodium hypophosphite - 15. Solution temperature - 85 ... 87 ° C, pH - 4.5, growth rate - 12 ... 15 microns /h

Nickel chloride - 45, ammonium chloride - 45, sodium citrate - 45, sodium hypophosphite - 20. Solution temperature - 90 ° C, pH - 8.5, growth rate - 18 ... 20 microns / h.

Nickel chloride - 30, ammonium chloride - 30, sodium succinic acid - 100, ammonia (25% solution - 35, sodium hypophosphite - 25).
Temperature - 90°C, pH - 8...8.5, growth rate - 8...12 µm/h.

Nickel chloride - 45, ammonium chloride - 45, sodium acetate - 45, sodium hypophosphite - 20. Solution temperature - 88 .... 90 ° C, pH - 8 ... 9, growth rate - 18 ... 20 microns / h.

Nickel sulphate - 30, ammonium sulphate - 30, sodium hypophosphite - 10. Solution temperature - 85°C, pH - 8.2...8.5, growth rate - 15...18 µm/h.

Attention! According to existing state standards, a single-layer nickel coating per 1 cm2 has several tens of through (to the base metal) pores. Naturally, in the open air, a nickel-plated steel part will quickly become covered with a “rash” of rust.

In a modern car, for example, the bumper is covered with a double layer (a sublayer of copper, and chrome on top) and even a triple layer (copper - nickel - chrome). But even this does not save the part from rust, since according to GOST and the triple coating has several pores per 1 cm2. What to do? Exit - in the surface treatment of the coating special formulations that close the pores.

Wipe the part with a nickel (or other) coating with a slurry of magnesium oxide and water and immediately lower it for 1 ... 2 minutes in a 50% hydrochloric acid solution.

After heat treatment, lower the part that has not yet cooled down into non-vitaminized fish oil (preferably old, unsuitable for its intended purpose).

Wipe the nickel-plated surface of the part 2...3 times with the composition of LPS (easy penetrating lubricant).

In the last two cases, excess fat (grease) is removed from the surface with gasoline in a day.

Processing fish oil large surfaces (bumpers, car moldings) are carried out like this. In hot weather, wipe them with fish oil twice with a break of 12-14 hours. Then, after 2 days, excess fat is removed with gasoline.

The effectiveness of such processing is characterized by the following example. Nickel-plated fishing hooks begin to rust immediately after the first sea fishing. Treated with fish oil, the same hooks do not corrode almost all summer season sea ​​fishing.

Chrome plating

Chemical chromium plating allows you to get a gray coating on the surface of metal parts, which, after polishing, acquires the desired shine. Chrome adheres well to nickel plating. The presence of phosphorus in chemically produced chromium greatly increases its hardness. Heat treatment for chrome plating is necessary.

Below are tried and tested recipes. chemical chromium plating.

Compositions of solutions for chemical chromium plating (g/l)

Chromium fluoride - 14, sodium citrate - 7, acetic acid - 10 ml, sodium hypophosphite - 7. Solution temperature - 85 ... 90 ° C, pH - 8 ... 11, growth rate - 1.0 ... 2 .5 µm/h.

Chromium fluoride - 16, chromium chloride - 1, sodium acetate - 10, sodium oxalate - 4.5, sodium hypophosphite - 10. Solution temperature - 75 ... 90 ° C, pH - 4 ... 6, growth rate - 2 ...2.5 µm/h.

Chromium fluoride - 17, chromium chloride - 1.2, sodium citrate - 8.5, sodium hypophosphite - 8.5. Solution temperature - 85...90°C, pH - 8...11, growth rate - 1...2.5 µm/h.

Chromium acetate - 30, nickel acetate - 1, sodium glycolate - 40, sodium acetate - 20, sodium citrate - 40, acetic acid - 14 ml, sodium hydroxide - 14, sodium hypophosphite - 15. Solution temperature - 99 ° C, pH - 4...6, growth rate - up to 2.5 µm/h.

Chromium fluoride - 5 ... 10, chromium chloride - 5 ... 10, sodium citrate - 20 ... 30, sodium pyrophosphate (replacing sodium hypophosphite) - 50 ... 75.
Solution temperature - 100°C, pH - 7.5...9, growth rate - 2...2.5 µm/h.

Boronickel plating

The film of this dual alloy has increased hardness (especially after heat treatment), high melting point, high wear resistance and significant corrosion resistance. All this allows the use of such a coating in various responsible home-made designs. Below are the recipes for solutions in which boronickeling is carried out.

Compositions of solutions for chemical boron nickel plating (g/l)

Nickel chloride - 20, sodium hydroxide - 40, ammonia (25% solution): - 11, sodium borohydride - 0.7, ethylenediamine (98% solution) - 4.5. Solution temperature - 97°C, growth rate - 10 µm/h.

Nickel sulfate - 30, triethylsyntetramine - 0.9, sodium hydroxide - 40, ammonia (25% solution) - 13, sodium borohydride - 1. Solution temperature - 97 C, growth rate - 2.5 μm / h.

Nickel chloride - 20, sodium hydroxide - 40, Rochelle salt - 65, ammonia (25% solution) - 13, sodium borohydride - 0.7. Solution temperature - 97°C, growth rate - 1.5 µm/h.

Caustic soda - 4 ... 40, potassium metabisulphite - 1 ... 1.5, potassium sodium tartrate - 30 ... 35, nickel chloride - 10 ... 30, ethylenediamine (50% solution) - 10 ... 30 , sodium borohydride - 0.6 ... 1.2. Solution temperature - 40...60°C, growth rate - up to 30 µm/h.

Solutions are prepared in the same way as for nickel plating: first, everything except sodium borohydride is dissolved, the solution is heated and sodium borohydride is dissolved.

Borocobalting

The use of this chemical process makes it possible to obtain a film of particularly high hardness. It is used to repair friction pairs, where increased wear resistance of the coating is required.

Compositions of solutions for boron cobalt treatment (g/l)

Cobalt chloride - 20, sodium hydroxide - 40, sodium citrate - 100, ethylenediamine - 60, ammonium chloride - 10, sodium borohydride - 1. Solution temperature - 60 ° C, pH - 14, growth rate - 1.5 .. .2.5 µm/h.

Cobalt acetate - 19, ammonia (25% solution) - 250, potassium tartrate - 56, sodium borohydride - 8.3. Solution temperature - 50°С, pH - 12.5, growth rate - 3 µm/h.

Cobalt sulphate - 180, boric acid - 25, dimethylborazan - 37. Solution temperature - 18°C, pH - 4, growth rate - 6 µm/h.

Cobalt chloride - 24, ethylenediamine - 24, dimethylborazan - 3.5. Solution temperature - 70 C, pH - 11, growth rate - 1 µm/h.

The solution is prepared in the same way as boronickel.

Cadmium plating

On the farm, it is often necessary to use fasteners coated with cadmium. This is especially true for parts that are operated outdoors.

It is noted that chemically obtained cadmium coatings adhere well to the base metal even without heat treatment.

Cadmium chloride - 50, ethylenediamine - 100. Cadmium should be in contact with parts (suspension on cadmium wire, small parts are sprinkled with cadmium powder). Solution temperature - 65°C, pH - 6...9, growth rate - 4 µm/h.

Attention! Ethylenediamine is dissolved last in the solution (after heating).

copper plating

Chemical copper plating is most often used in the manufacture of printed circuit boards for radio electronics, in electroforming, for metallizing plastics, for double coating some metals with others.

Compositions of solutions for copper plating (g/l)

Copper sulphate - 10, sulfuric acid - 10. Solution temperature - 15...25°C, growth rate - 10 µm/h.

Potassium-sodium tartrate - 150, copper sulphate - 30, caustic soda - 80. Solution temperature - 15 ... 25 ° C, growth rate - 12 μm / h.

Copper sulphate - 10 ... 50, caustic soda - 10 ... 30, Rochelle salt 40 ... 70, formalin (40% solution) - 15 ... 25. Solution temperature - 20°C, growth rate - 10 µm/h.

Sulfuric copper - 8...50, sulfuric acid - 8...50. Solution temperature - 20°C, growth rate - 8 µm/h.

Copper sulphate - 63, potassium tartrate - 115, sodium carbonate - 143. Solution temperature - 20 C, growth rate - 15 µm/h.

Copper sulphate - 80 ... 100, caustic soda - 80 ..., 100, sodium carbonate - 25 ... 30, nickel chloride - 2 ... 4, Rochelle salt - 150 ... 180, formalin (40% - solution) - 30...35. Solution temperature - 20°C, growth rate - 10 µm/h. This solution makes it possible to obtain films with a low nickel content.

Copper sulfate - 25 ... 35, sodium hydroxide - 30 ... 40, sodium carbonate - 20-30, trilon B - 80 ... 90, formalin (40% solution) - 20 ... 25, rhodanine - 0.003 ... 0.005, potassium ferricyanide (red blood salt) - 0.1..0.15. Solution temperature - 18...25°C, growth rate - 8 µm/h.

This solution is highly stable over time and makes it possible to obtain thick copper films.

To improve the adhesion of the film to the base metal, heat treatment is the same as for nickel.

Silvering

Silver plating of metal surfaces is perhaps the most popular process among craftsmen, which they use in their work. Dozens of examples could be given. For example, restoration of the silver layer on cupronickel cutlery, silvering of samovars and other household items.

For silver chasers together with chemical staining metal surfaces (it will be discussed below) - a way to increase the artistic value of chased paintings. Imagine a minted ancient warrior with silver plated chain mail and a helmet.

The process of chemical silvering can be carried out using solutions and pastes. The latter is preferable when processing large surfaces (for example, when silvering samovars or parts of large chased paintings).

Composition of solutions for silvering (g/l)

Silver chloride - 7.5, potassium ferricyanide - 120, potassium carbonate - 80. The temperature of the working solution is about 100 ° C. Processing time - until the desired thickness of the silver layer is obtained.

Silver chloride - 10, sodium chloride - 20, acid potassium tartrate - 20. Processing - in a boiling solution.

Silver chloride - 20, potassium ferricyanide - 100, potassium carbonate - 100, ammonia (30% solution) - 100, sodium chloride - 40. Processing - in a boiling solution.

First, a paste is prepared from silver chloride - 30 g, tartaric acid - 250 g, sodium chloride - 1250, and everything is diluted with water to the density of sour cream. 10 ... 15 g of paste is dissolved in 1 liter of boiling water. Processing - in a boiling solution.

Details are hung in solutions for silvering on zinc wires (strips).

The processing time is determined visually. It should be noted here that brass is better silvered than copper. On the latter it is necessary to apply a fairly thick layer of silver in order to dark copper would not shine through the coating layer.

One more note. Solutions with silver salts cannot be stored for a long time, as explosive components can be formed in this case. The same applies to all liquid pastes.

Compositions of pastes for silvering.

2 g of lapis pencil is dissolved in 300 ml of warm water (sold in pharmacies, it is a mixture of silver nitrate and amino acid potassium, taken in a ratio of 1: 2 (by weight). A 10% sodium chloride solution is gradually added to the resulting solution until it stops The curdled precipitate of silver chloride is filtered off and thoroughly washed in 5-6 waters.

Dissolve 20 g of sodium thiosulfite in 100 ml of water. Silver chloride is added to the resulting solution until it no longer dissolves. The solution is filtered and tooth powder is added to it to the consistency of liquid sour cream. This paste is rubbed (silvered) with a cotton swab.

Lapis pencil - 15, lemon acid(food) - 55, ammonium chloride - 30. Each component is ground into powder before mixing. The content of components - in% (by weight).

Silver chloride - 3, sodium chloride - 3, sodium carbonate - 6, chalk - 2. The content of components - in parts (by weight).

Silver chloride - 3, sodium chloride - 8, potassium tartrate - 8, chalk - 4. Content of components - in parts (by weight).

Silver nitrate - 1, sodium chloride - 2. Content of components - in parts (by weight).

The last four pastes are used as follows. Finely divided components are mixed. With a wet swab, powdering it with a dry mixture of chemicals, they rub (silver) the desired part. The mixture is added all the time, constantly moistening the swab.

When silvering aluminum and its alloys, the parts are first galvanized and then coated with silver.

Zincate treatment is carried out in one of the following solutions.

Compositions of solutions for zincate treatment (g/l)

For aluminum

Caustic soda - 250, zinc oxide - 55. Solution temperature - 20°C, treatment time - 3...5 s.

Caustic soda - 120, zinc sulfate - 40. Solution temperature - 20°C, processing time - 1.5...2.0 min. To obtain a solution, first caustic soda is dissolved in one half of the water, and zinc sulfate is dissolved in the other. Then both solutions are poured together.

For duralumin

Caustic soda - 10, zinc oxide - 5, Rochelle salt - 10. Solution temperature - 20°C, processing time - 1...2 min.

After zincate treatment, the parts are silvered in any of the above solutions. However, the following solutions (g / l) are considered the best.

Silver nitrate - 100, ammonium fluoride - 100. Solution temperature - 20°C.

Silver fluoride - 100, ammonium nitrate - 100. Solution temperature - 20°C.

Tinning

Chemical tinning of surfaces of parts is used as an anti-corrosion coating and as a preliminary process (for aluminum and its alloys) before soft soldering. Below are compositions for tinning some metals.

Compositions for tinning (g/l)

For steel

Stannous chloride (fused) - 1, ammonia alum - 15. Tinning is carried out in a boiling solution, the growth rate is 5 ... 8 microns / h.

Tin chloride - 10, aluminum-ammonium sulphate - 300. Tinning is carried out in a boiling solution, the growth rate is 5 microns / h.

Stannous chloride - 20, Rochelle salt - 10. Solution temperature - 80°C, growth rate - 3...5 µm/h.

Stannous chloride - 3 ... 4, Rochelle salt - until saturation. Solution temperature - 90...100°С, growth rate - 4...7 µm/h.

For copper and its alloys

Stannous chloride - 1, potassium tartrate - 10. Tinning is carried out in a boiling solution, the growth rate is 10 μm / h.

Stannous chloride - 20, sodium lactate - 200. Solution temperature - 20°C, growth rate - 10 µm/h.

Stannous chloride - 8, thiourea - 40...45, sulfuric acid - 30...40. Solution temperature - 20°C, growth rate - 15 µm/h.

Stannous chloride - 8...20, thiourea - 80...90, hydrochloric acid - 6.5...7.5, sodium chloride - 70...80. Solution temperature - 50...100°C, growth rate - 8 µm/h.

Stannous chloride - 5.5, thiourea - 50, tartaric acid - 35. Solution temperature - 60 ... 70 ° C, growth rate - 5 ... 7 μm / h.

When tinning parts made of copper and its alloys, they are hung on zinc pendants. Small parts are “powdered” with zinc filings.

For aluminum and its alloys

The tinning of aluminum and its alloys is preceded by some additional processes. First, the parts degreased with acetone or gasoline B-70 are treated for 5 minutes at a temperature of 70 ° C of the following composition (g / l): sodium carbonate - 56, sodium phosphate - 56. Then the parts are lowered for 30 s into a 50% solution of nitric acid, rinse thoroughly under running water and immediately place in one of the solutions (for tinning) below.

Sodium stannate - 30, sodium hydroxide - 20. Solution temperature - 50...60°C, growth rate - 4 µm/h.

Sodium stannate - 20 ... 80, potassium pyrophosphate - 30 ... 120, sodium hydroxide - 1.5..L, 7, ammonium oxalate - 10 ... 20. Solution temperature - 20...40°C, growth rate - 5 µm/h.

Removal of metal coatings

Usually this process is necessary to remove low-quality metal films or to clean any metal product being restored.

All of the following solutions work faster at elevated temperatures.

Compositions of solutions for removing metal coatings in parts (by volume)

For steel removing nickel from steel

Nitric acid - 2, sulfuric acid - 1, iron sulphate (oxide) - 5 ... 10. The temperature of the mixture is 20°C.

Nitric acid - 8, water - 2. Solution temperature - 20 C.

Nitric acid - 7, acetic acid (glacial) - 3. Mixture temperature - 30°C.

For removing nickel from copper and its alloys (g/l)

Nitrobenzoic acid - 40 ... 75, sulfuric acid - 180. Solution temperature - 80 ... 90 C.

Nitrobenzoic acid - 35, ethylenediamine - 65, thiourea - 5...7. Solution temperature - 20...80°C.

Technical nitric acid is used to remove nickel from aluminum and its alloys. The temperature of the acid is 50°C.

For removing copper from steel

Nitrobenzoic acid - 90, diethylenetriamine - 150, ammonium chloride - 50. Solution temperature - 80°C.

Sodium pyrosulfate - 70, ammonia (25% solution) - 330. Solution temperature - 60 °.

Sulfuric acid - 50, chromic anhydride - 500. Solution temperature - 20°C.

For removing copper from aluminum and its alloys (zinc finish)

Chromic anhydride - 480, sulfuric acid - 40. Solution temperature - 20...70°C.

Technical nitric acid. The temperature of the solution is 50°C.

For removing silver from steel

Nitric acid - 50, sulfuric acid - 850. Temperature - 80°C.

Nitric acid technical. Temperature - 20°C.

Silver is removed from copper and its alloys with technical nitric acid. Temperature - 20°C.

Chrome is removed from steel with a solution of caustic soda (200 g/l). Solution temperature - 20 C.

Chromium is removed from copper and its alloys with 10% hydrochloric acid. The temperature of the solution is 20°C.

Zinc is removed from steel with 10% hydrochloric acid - 200 g / l. The temperature of the solution is 20°C.

Zinc is removed from copper and its alloys with concentrated sulfuric acid. Temperature - 20 C.

Cadmium and zinc are removed from any metals with a solution of aluminum nitrate (120 g/l). The temperature of the solution is 20°C.

Tin from steel is removed with a solution containing sodium hydroxide - 120, nitrobenzoic acid - 30. The temperature of the solution is 20°C.

Tin is removed from copper and its alloys in a solution of ferric chloride - 75 ... 100, copper sulfate - 135 ... 160, acetic acid (glacial) - 175. The temperature of the solution is 20 ° C.

Chemical oxidation and coloring of metals

Chemical oxidation and coloring of the surface of metal parts are intended to create an anti-corrosion coating on the surface of the parts and enhance the decorative effect of the coating.

In ancient times, people already knew how to oxidize their crafts, changing their color (silver blackening, gold coloring, etc.), burn steel objects (heating a steel part to 220 ... 325 ° C, they lubricated it with hemp oil).

Compositions of solutions for oxidation and coloring of steel (g/l)

Note that before oxidation, the part is ground or polished, degreased and decapitated.

Black color

Caustic soda - 750, sodium nitrate - 175. Solution temperature - 135°C, processing time - 90 minutes. The film is dense, shiny.

Caustic soda - 500, sodium nitrate - 500. Solution temperature - 140°C, processing time - 9 minutes. The film is intense.

Caustic soda - 1500, sodium nitrate - 30. Solution temperature - 150°C, processing time - 10 min. The film is matte.

Caustic soda - 750, sodium nitrate - 225, sodium nitrite - 60. Solution temperature - 140 ° C, processing time - 90 minutes. The film is shiny.

Calcium nitrate - 30, phosphoric acid - 1, manganese peroxide - 1. Solution temperature - 100°C, processing time - 45 min. The film is matte.

All of the above methods are characterized by a high working temperature of the solutions, which, of course, does not allow processing large parts. However, there is one "low-temperature solution" suitable for this business (g / l): sodium thiosulfate - 80, ammonium chloride - 60, phosphoric acid - 7, nitric acid - 3. Solution temperature - 20 ° C, processing time - 60 minutes . The film is black, matte.

After oxidation (blackening) of steel parts, they are treated for 15 minutes in a solution of potassium chromium peak (120 g/l) at a temperature of 60°C.

Then the parts are washed, dried and coated with any neutral machine oil.

Blue

Hydrochloric acid - 30, ferric chloride - 30, mercury nitrate - 30, ethyl alcohol - 120. Solution temperature - 20 ... 25 ° C, processing time - up to 12 hours.

Sodium hydrosulphide - 120, lead acetate - 30. Solution temperature - 90...100°C, processing time - 20...30 min.

Blue color

Lead acetate - 15 ... 20, sodium thiosulfate - 60, acetic acid (glacial) - 15 ... 30. The temperature of the solution is 80°C. The processing time depends on the intensity of the color.

Compositions of solutions for oxidation and coloring of copper (g/l)

bluish black colors

Caustic soda - 600 ... 650, sodium nitrate - 100 ... 200. Solution temperature - 140°C, processing time - 2 hours.

Caustic soda - 550, sodium nitrite - 150 ... 200. Solution temperature - 135...140°С, processing time - 15...40 min.

Caustic soda - 700...800, sodium nitrate - 200...250, sodium nitrite -50...70. Solution temperature - 140...150°С, processing time - 15...60 min.

Caustic soda - 50 ... 60, potassium persulfate - 14 ... 16. Solution temperature - 60...65 C, processing time - 5...8 min.

Potassium sulfide - 150. Solution temperature - 30°C, processing time - 5...7 min.

In addition to the above, a solution of the so-called sulfuric liver is used. Sulfur liver is obtained by fusing in an iron can for 10 ... 15 minutes (with stirring) 1 part (by weight) of sulfur with 2 parts of potassium carbonate (potash). The latter can be replaced by the same amount of sodium carbonate or caustic soda.

The glassy mass of sulfuric liver is poured onto an iron sheet, cooled and crushed to a powder. Store sulfur liver in an airtight container.

A solution of sulfuric liver is prepared in an enamel bowl at the rate of 30...150 g/l, the temperature of the solution is 25...100°C, the processing time is determined visually.

With a solution of sulfuric liver, in addition to copper, silver can be well blackened and steel satisfactorily.

Green color

Copper nitrate - 200, ammonia (25% solution) - 300, ammonium chloride - 400, sodium acetate - 400. Solution temperature - 15...25°C. The color intensity is determined visually.

Brown color

Potassium chloride - 45, nickel sulphate - 20, copper sulphate - 100. Solution temperature - 90...100°C, color intensity is determined visually.

Brownish yellow color

Caustic soda - 50, potassium persulfate - 8. Solution temperature - 100°C, processing time - 5...20 min.

Blue

Sodium thiosulfate - 160, lead acetate - 40. Solution temperature - 40 ... 100 ° C, processing time - up to 10 minutes.

Compositions for oxidation and coloring of brass (g/l)

Black color

Copper carbonate - 200, ammonia (25% solution) - 100. Solution temperature - 30 ... 40 ° C, processing time - 2 ... 5 minutes.

Copper bicarbonate - 60, ammonia (25% solution) - 500, brass (sawdust) - 0.5. Solution temperature - 60...80°С, processing time - up to 30 min.

Brown color

Potassium chloride - 45, nickel sulfate - 20, copper sulfate - 105. Solution temperature - 90 ... 100 ° C, processing time - up to 10 minutes.

Copper sulphate - 50, sodium thiosulfate - 50. Solution temperature - 60 ... 80 ° C, processing time - up to 20 minutes.

Sodium sulfate - 100. Solution temperature - 70°C, processing time - up to 20 minutes.

Copper sulphate - 50, potassium permanganate - 5. Solution temperature - 18 ... 25 ° C, processing time - up to 60 minutes.

Blue

Lead acetate - 20, sodium thiosulfate - 60, acetic acid (essence) - 30. Solution temperature - 80 ° C, processing time - 7 minutes.

3 green color

Nickel ammonium sulphate - 60, sodium thiosulfate - 60. Solution temperature - 70 ... 75 ° C, processing time - up to 20 minutes.

Copper nitrate - 200, ammonia (25% solution) - 300, ammonium chloride - 400, sodium acetate - 400. Solution temperature - 20 ° C, processing time - up to 60 minutes.

Compositions for oxidation and coloring of bronze (g/l)

Green color

Ammonium chloride - 30, 5% acetic acid - 15, medium acetic copper salt - 5. Solution temperature - 25...40°C. Hereinafter, the color intensity of bronze is determined visually.

Ammonium chloride - 16, acidic potassium oxalate - 4, 5% acetic acid - 1. Solution temperature - 25...60°C.

Copper nitrate - 10, ammonium chloride - 10, zinc chloride - 10. Solution temperature - 18...25°C.

yellow- green color

Nitrate copper - 200, sodium chloride - 20. Solution temperature - 25°C.

Blue to yellow-green

Depending on the processing time, it is possible to obtain colors from blue to yellow-green in a solution containing ammonium carbonate - 250, ammonium chloride - 250. The temperature of the solution is 18 ... 25 ° C.

Patination (giving the appearance of old bronze) is carried out in the following solution: sulfuric liver - 25, ammonia (25% solution) - 10. Solution temperature - 18 ... 25 ° C.

Compositions for oxidation and coloring of silver (g/l)

Black color

Sulfuric liver - 20...80. Solution temperature - 60..70°С. Hereinafter, the color intensity is determined visually.

Ammonium carbonate - 10, potassium sulfide - 25. Solution temperature - 40...60°C.

Potassium sulphate - 10. Solution temperature - 60°C.

Copper sulphate - 2, ammonium nitrate - 1, ammonia (5% solution) - 2, acetic acid (essence) - 10. Solution temperature - 25...40°C. The content of the components in this solution is given in parts (by weight).

Brown color

A solution of ammonium sulphate - 20 g / l. Solution temperature - 60...80°C.

Copper sulphate - 10, ammonia (5% solution) - 5, acetic acid - 100. Solution temperature - 30...60°C. The content of the components in the solution - in parts (by weight).

Copper sulphate - 100, 5% acetic acid - 100, ammonium chloride - 5. Solution temperature - 40...60°C. The content of the components in the solution - in parts (by weight).

Copper sulphate - 20, potassium nitrate - 10, ammonium chloride - 20, 5% acetic acid - 100. Solution temperature - 25...40°C. The content of the components in the solution - in parts (by weight).

Blue

Sulfuric liver - 1.5, ammonium carbonate - 10. Solution temperature - 60°C.

Sulfuric liver - 15, ammonium chloride - 40. Solution temperature - 40...60°C.

Green color

Iodine - 100, hydrochloric acid - 300. Solution temperature - 20°C.

Iodine - 11.5, potassium iodide - 11.5. The temperature of the solution is 20°C.

Attention! When dyeing silver green, you must work in the dark!

Composition for oxidation and coloring of nickel (g/l)

Nickel can only be painted black. The solution (g/l) contains: ammonium persulfate - 200, sodium sulfate - 100, iron sulfate - 9, ammonium thiocyanate - 6. Solution temperature - 20...25°C, processing time - 1-2 minutes.

Compositions for the oxidation of aluminum and its alloys (g/l)

Black color

Ammonium molybdate - 10...20, ammonium chloride - 5...15. Solution temperature - 90...100°С, treatment time - 2...10 min.

Grey colour

Arsenic trioxide - 70...75, sodium carbonate - 70...75. Solution temperature - boiling, processing time - 1...2 min.

Green color

Orthophosphoric acid - 40 ... 50, acidic potassium fluoride - 3 ... 5, chromic anhydride - 5 ... 7. Solution temperature - 20...40 C, processing time - 5...7 min.

Orange color

Chromic anhydride - 3...5, sodium fluorine silicate - 3...5. Solution temperature - 20...40°С, processing time - 8...10 min.

tan color

Sodium carbonate - 40 ... 50, sodium chlorate - 10 ... 15, caustic soda - 2 ... 2.5. Solution temperature - 80...100°С, processing time - 3...20 min.

Protective compounds

Often, the craftsman needs to process (paint, cover with another metal, etc.) only part of the craft, and leave the rest of the surface unchanged.
To do this, the surface that does not need to be covered is painted over with a protective compound that prevents the formation of a particular film.

The most accessible, but non-heat-resistant protective coatings are waxy substances (wax, stearin, paraffin, ceresin) dissolved in turpentine. To prepare such a coating, wax and turpentine are usually mixed in a ratio of 2: 9 (by weight). Prepare this composition as follows. Wax is melted in a water bath and warm turpentine is introduced into it. To protective compound would be contrast (its presence could be clearly seen, controlled), a small amount of dark-colored paint soluble in alcohol is introduced into the composition. If this is not available, it is easy to introduce a small amount of dark shoe cream into the composition.

You can give a recipe that is more complex in composition,% (by weight): paraffin - 70, beeswax - 10, rosin - 10, pitch varnish (Kuzbasslak) - 10. All components are mixed, melted over low heat and mixed thoroughly.

Wax-like protective compounds are applied hot with a brush or swab. All of them are designed for operating temperatures up to 70°C.
Somewhat better heat resistance (operating temperature up to 85°С) is possessed by protective compositions based on asphalt, bituminous and pitch varnishes. Usually they are thinned with turpentine in a ratio of 1:1 (by weight). The cold composition is applied to the surface of the part with a brush or swab. Drying time - 12...16 hours.

Perchlorovinyl paints, varnishes and enamels withstand temperatures up to 95°C, oil-bitumen varnishes and enamels, asphalt-oil and bakelite varnishes - up to 120°C.

The most acid-resistant protective composition is a mixture of 88N glue (or Moment) and filler (porcelain flour, talc, kaolin, chromium oxide), taken in the ratio: 1:1 (by weight). The required viscosity is obtained by adding to the mixture a solvent consisting of 2 parts (by volume) of B-70 gasoline and 1 part of ethyl acetate (or butyl acetate). The working temperature of such a protective composition is up to 150 C.

A good protective composition is epoxy varnish (or putty). Operating temperature - up to 160°С.

NICKEL PLATE, the technical process of applying to the surface of metals b. or m. thin film of nickel metal or nickel alloys; the purpose of this application is to reduce metal corrosion, increase the hardness of the outer layer, increase or change the reflectivity of the surface, make it more beautiful view. First obtained by Bettger in 1842 and commercially carried out in the USA since 1860, nickel plating has now become one of the most widely adopted metal plating methods by industry.

The existing numerous methods of nickel plating can be divided into two main groups: contact methods and methods electroplating; at present, the latter are especially often resorted to. The deposition of a nickel film is applied to the surfaces of various metals, and in accordance with the nature of nickel plating, they can be divided into groups: 1) copper, brass, bronze, zinc, 2) iron, 3) tin, lead and from alloys such as Britain-metal, 4 ) aluminum and aluminum alloys. Nickel films provide quite satisfactory protection of iron against rust in interior spaces.

However, they are insufficient in the open air; in addition, hot fats, vinegar, tea, mustard act on polished nickel-plated surfaces, as a result of which nickel-plated tableware and kitchen utensils become stained. In those cases where quite reliable protection from the effects of bad weather is required and at the same time an elegant appearance of a nickel-plated surface, iron should be used. a double film is applied - zinc, and then nickel. This method of double coating (zinc and then nickel) is also applied to the so-called. corset steel. If it is necessary to obtain particularly resistant films, such as, for example, on wires, nickel and platinum are deposited simultaneously, the content of the latter being gradually increased from 25% to 100% and, finally, the object is calcined in a hydrogen jet at 900-1000 ° C. Large items such as cookers, centrifuge drums or fans, if economic conditions cannot be made of pure nickel, but not resistant enough with a nickel film over iron or copper, lined with a lead layer of several mm, and over it with a nickel layer of 1-2 mm. The rusting of nickel-plated iron and steel products is due to the presence of electrolyte remaining in the thin pores of the nickel film. This phenomenon is eliminated if the products are kept in oil at 200°C before nickel plating, degreased after cooling, slightly copper-plated, then nickel-plated in a low-current nickel citrate bath, and finally dried in a cabinet at 200°C; then moisture is removed from the pores, which are clogged by the oil in them.

There are a number of proposals to apply double protective films on cast iron, iron or steel sheets, wires and strips in the reverse order of the above, i.e., first coat the products with a thin film of nickel with contact or electrolytically, and then immersed in a bath of molten zinc or tin (Vivien and Lefebvre, 1860). It is also proposed to add a certain amount of nickel to an alloy of 25-28 kg of zinc, 47-49 kg of lead and 15 kg of tin, which is used for hot coating of iron sheets. The resistance of surfaces of aluminum and its alloys against salt and sea ​​water m. b. achieved by electroplating on them, after cleaning them with a sand jet, successive layers of nickel 6 µm thick, copper 20 µm and then again nickel 50 µm, after which the surface is polished. The resistance of aluminum against 15% sodium hydroxide is achieved by a nickel film 40 microns thick. In some cases, a coating is applied not with pure nickel, but with an alloy, for example, nickel-copper; for this, electrolysis is carried out in a bath containing cations in the ratio of the required alloy; the deposited film is then transferred to the alloy by heating the product to red-hot heat.

Contact nickel plating. Steel objects, according to the instructions of F. Stolba (1876), after polishing and proper degreasing, are boiled in a bath of 10-15% aqueous solution of pure zinc chloride, to which nickel sulphate is added until green turbidity is formed from the basic nickel salt. Nickel plating takes about 1 hour. After that, the object is rinsed in water with chalk, and the bath, after filtering and adding nickel salt, can be used again. The resulting nickel film is thin but holds firmly. To increase the temperature of the bath, it was proposed either to carry out the process under pressure (F. Stolba, 1880) or to use a bath with a concentrated solution of zinc chloride. In order to avoid rusting of objects, they are kept for 12 hours in milk of lime. A more complex bath for iron objects, previously copper-plated in a bath of 250 g of copper sulfate in 23 liters of water with a few drops of sulfuric acid, contains 20 g of cream of tartar, 10 g of ammonia, 5 g of sodium chloride, 20 g of tin chloride, 30 g of nickel sulfate and 50 g double sulfate nickel-ammonium salt.

electroplated nickel plating. Depletion of the nickel bath m. b. prevented by rather easy dissolution of nickel anodes. Rolled, and especially from pure nickel, anodes are difficult to dissolve, and therefore, in technical nickel plating, nickel bars containing up to 10% iron are used as anodes. However, such anodes lead to the deposition of iron on the object, and the presence of iron in the nickel film entails a number of defects in nickel plating. As pointed out by Kalgane and Gammage (1908), it is impossible to obtain, with anodes containing iron, a deposit completely free of the latter. But the nickel deposit will already contain only 0.10-0.14% iron, if the iron content in the anodes is reduced to 7.5%; the iron content of the precipitate can be further reduced by enclosing the anodes in fabric bags, while the rotation of the electrodes leads to an increased content of iron in the precipitate and to a decrease in its yield. The presence of iron in the nickel film leads to the deposition of deposits with a gradually decreasing iron content and therefore inhomogeneous in terms of mechanical properties at different depths; K. Engemann (1911) considers this inhomogeneity to be the only reason for the easy detachment of nickel films. The presence of iron m. the cause of a number of other defects in nickel plating (see table), for example, the ease of rusting of films.

Vice	Cause	measure of struggle
Nickel precipitation does not occur, there is no gas formation	Power source not working	Verification and renewal of the energy source
	Wires connected incorrectly	Switching wires
	Bath is too cold	Heating the bath to a temperature above 15°C
	The bath is too sour	Adding an aqueous solution ammonia or an aqueous suspension of nickel carbonate with continuous stirring and frequent testing for Congo paper
	Bath contains zinc	The bath is made alkaline with nickel carbonate, stirred for several hours, filtered and acidified with 10% sulfuric acid.
Incomplete coverage of the object with nickel film	Insufficient current	Objects are suspended at equal distances from the anodes, the bath is heated to at least 20 ° C
	Very deep concavities on the surface of the object	Small auxiliary anodes are installed, inserted into the recesses of the object
	Bath alkalinity	Careful acidification of the bath with 10% sulfuric acid while stirring and constantly testing with litmus paper
Slight chipping of white or yellow-nickelpolishing films	Contamination of the surface of objects with oxides and grease	Additional surface cleaning
	Too much voltage (above 4 v)	Increase the number of nickel-plated objects or reduce the voltage to 2.5-3 V
	Bath too acidic	Neutralization with ammonia or an aqueous suspension of nickel carbonate
	Nickel bath poverty	Removing some of the electrolyte and adding nickel salt until the bath is a normal green color
	Incorrect viscosity and surface tension of the bath	Addition of glycerin or amyl alcohol, or herbal decoctions, or other colloids
	Isolation of hydrogen ions	Addition of oxidizers or absorbers of hydrogen; application of unbalanced alternating current
	Inappropriate surface preparation of objects	Roughening surfaces, mechanically or chemically, coating them with a thin layer of nickel from a hot solution of nickel chloride or a cold concentrated solution of ethyl nickel sulfate
Nickel film lagging or tearing when objects are bent and stretched	The presence of capillary layers of electrolyte	Drying and heating of objects up to 250-270°С
Insufficient machinability of sheets coated with a thick layer of nickel	Probably the same	Rinsing, drying without access to air and finally heating to a low red-hot heat
Dimpled surface and film riddled with countless pores	Dust and fiber particles floating in the bath	The bath is boiled, filtered and the correct reaction is established in it.
	Formation of gas bubbles	Tapping on a current-carrying rod. Bubbles are removed; establish a slightly acidic reaction
Surface roughness and unevenness	Hydrogen evolution	The introduction of hydrogen-binding free chlorine in gaseous form from time to time through a jet or in an aqueous solution; with somewhat less success, chlorine might. replaced by bromine; the addition of cobalt chloride solution is highly recommended
Insufficient film flexibility	High bath resistance	Sodium Salt Supplement
Film yellowness; the surface becomes matte, and then gets yellow and dark yellow	The presence of iron impurities in the bath, the content of which increases in old baths	Avoid old tubs, don't move tubs too much, work with weak currents
Blackness of the film, dark streaks at the lagging points at the correct current density	The content of foreign metals in the bath (up to 1%)	Foreign metal removal
	Lack of conductive salts	The addition of conductive salts in the amount of 2-3 kg per 100 liters of bath: ammonia, potassium chloride and sodium chloride give an increase in conductivity by 84.31 and 18%, respectively
	Nickel salt bath poverty	Nickel Salt Additive
Surface tan	Too high conductivity of the bath due to its excessive strength	Control of bath concentration (e.g. constant density at 5° Vẻ) and current density
Banding	Dirt produced by the polishing wheel in small depressions	Elimination is difficult; achieved to a certain extent by instantaneous immersion in a cauldron of liquor or mechanical rubbing of objects
	Changes in concentration and the occurrence of liquid flows	Reducing current density and increasing bath temperature
Spotting	Insufficient cleaning of finished nickel-plated products	Thorough washing in running water of products after nickel plating, then immersion in boiling water clean water, shaking off products and drying in heated sawdust
Weak adhesion of nickel film to iron	Presence of rust	Thorough rust removal. Galvanic deposition of an intermediate layer from a cyanide bath, after which the film is thickened in an acid bath

The electrolytic bath for nickel plating is compiled by Ch. from double nickel-ammonium salt, and weak acids are added to eliminate basic salts. Higher acidity of the bath leads to harder films. It must be borne in mind that technical nickel vitriol is not suitable for baths, since it often contains copper; it should be removed by passing hydrogen sulfide through an aqueous solution of vitriol. Chlorine salts are also used, but with sulfate baths the precipitates are harder, whiter and more resistant than with chloride ones. It is beneficial to reduce the high resistance of a nickel bath by adding various conductive salts - especially ammonia and sodium chloride - and heating. The neutralization of excess sulfuric acid in old solutions is successfully carried out with nickel carbonate, which is obtained from a warm aqueous solution of nickel sulfate precipitated with soda. For the whiteness and smoothness of the films, a large number of proposals have been made to add to the nickel bath various organic acids (tartaric, citric, etc.) and their salts, for example, acetic, citric and tartaric salts of alkali and alkaline earth metals (Keith, 1878 ), propionic nickel, borate-tartrate salts of alkali metals. If it is necessary to obtain thick nickel deposits, it is proposed to add boric, benzoic, salicylic, gallic or pyrogallic acids, and in addition 10 drops of sulfuric, formic, lactic acid per 1 liter of bath to prevent polarization on the product. As Powell (1881) pointed out, the addition of benzoic acid (31 g per bath of 124 g of nickel sulfate and 93 g of nickel citrate in 4.5 liters of water) eliminates the need to use chemically pure salts and acids. The nickel precipitate has good properties also with a simple bath of nickel-ammonium sulfate, but under the condition of alkalinity of the solution, which is achieved by adding ammonia. Very good precipitates are obtained from a neutral solution of nickel fluoride-borate at room temperature (at temperatures above 35 ° C, the solution decomposes to form an insoluble basic salt) and a current density of 1.1-1.65 A / dm 2 . Here are some bath recipes. 1) 50 hours of sodium bisulfite, 4 hours of nickel oxide nitrate and 4 hours of concentrated ammonia are dissolved in 150 hours of water. 2) 10-12 hours nickel sulfate, 4 hours double nickel-ammonium sulfate, 1-3 hours. boric acid, 2 hours of magnesium chloride, 0.2-0.3 hours of ammonium citrate, topped up to 100 hours (total) of water. Current density 1.6 A/dm 2 deposits a film at a rate of 2 µm/h; By raising the temperature to 70°C, the resistance of the bath can be reduced by a factor of two or three, and thereby accelerate nickel plating. 3) An electrolyte of 72 g of double nickel-ammonium sulfate, 8 g of nickel sulfate, 48 g of boric acid and 1 liter of water is especially favorable for the softness and non-porosity of the precipitate, because it reduces the release of hydrogen.

Obtaining Nickel Films special kind . 1) A white film on zinc, tin, lead and britanium metal is obtained in a bath of 20 g of double nickel-ammonium sulfate and 20 g of nickel carbonate dissolved in 1 liter of boiling water and neutralized at 40 ° C with acetic acid; the bath must be kept neutral. 2) A dull white film is obtained in a bath of 60 g of double nickel ammonium sulfate, 15 g of recrystallized nickel sulfate, 7.4 g of ammonia, 23 g of sodium chloride and 15 g of boric acid per 1 liter of water; bath e. b concentrated to 10 ° Vẻ; voltage from 2 to 2.5 V. 3) A black film is obtained on surfaces carefully degreased or covered with a thin layer of white nickel by electrolysis in a bath of 60 g of double nickel-ammonium sulfate, 1.5 g of ammonium thiocyanate and about 1 g of sulphate zinc per 1 liter of water 4) A black film is also obtained in an electrolyte from 9 g of double nickel-ammonium sulfate salt in 1 liter of water, followed by the addition of 22 g of potassium thiocyanate, 15 g of copper carbonate and 15 g of white arsenic, previously dissolved in ammonium carbonate; the depth of the black tone increases with the content of arsenic in the solution. 5) A deep blue film is obtained in a bath of equal parts of double and simple nickel sulphate, brought to 12 ° Bẻ, and 2 hours of ammonia decoction of licorice root are added per liter; electrolysis lasts 1 hour at 3.5 V, and then another 1/2 hour at 1.4 V. salt and 60 g of nickel sulfate, dissolved in the smallest possible amount of boiling water, added to 50 cm 3 and then mixed with solutions of 30 g of nickel sulfate and 60 g of sodium thiocyanate, each in 0.5 l of water, after which the solution is added to 4, 5 l. The resulting black film is given a brown tint by immersing the product for several seconds in a bath of 100.6 g of iron perchlorate and 7.4 g of hydrochloric acid in 1 liter of water: after washing and drying, the surface of the product is varnished to fix the tone.

Nickel plating of aluminum and its alloys. Several processes have been proposed. 1) Surface preparation of aluminum products consists of degreasing, then cleaning with pumice and finally immersing in a 3% aqueous solution of potassium cyanide; after electrolysis in a nickel bath, the products are washed with cold water. 2) After washing with a 2% solution of potassium cyanide, the products are immersed in a solution of 1 g of ferric chloride (ferrochloride) per 0.5 l of water and technical hydrochloric acid until the surface becomes silver-white, and then nickel-plated for 5 minutes. at a voltage of 3 V. 3) Polishing products, removing the polishing composition with gasoline, exposure for several minutes in a warm aqueous solution of sodium phosphate, soda and resin, washing, immersing for a short time in a mixture of equal parts of 66% sulfuric acid (containing some ferric chloride) and 38% nitric acid, new washing and electrolysis in a bath containing nickel salt, bitter salt and boric acid; voltage 3-3.25 V. 4) According to J. Kanak and E. Tassilly: etching the product with boiling potassium alkali, brushing in milk of lime, 0.2% cyano-potassium bath, bath of 1 g of iron in 500 g of hydrochloric acid and 500 g of water, washing, nickel plating in a bath of 1 liter of water, 500 g of nickel chloride and 20 g of boric acid at a voltage of 2.5 V and a current density of 1 A/dm 2 , finally polishing the dull gray precipitate. The iron bath serves to roughen the aluminum surface and thus contributes to the strength with which the film is held on the metal. 5) According to Fischer, the nickel plating bath is made up of 50 g of nickel sulfate and 30 g of ammonia in 1 liter of water at a current density of 0.1-0.15 A / dm 2, in 2-3 hours a thick precipitate is obtained, which has a high gloss after polishing with stearin oil and Vienna lime. 6) hot tub(60 ° C) is made up of 3400 g of double nickel-ammonium sulfate, 1100 g of ammonium sulfate and 135 g of milk sugar in 27 liters of water. 7) cold bath contains nickel nitrate, potassium cyanide and ammonium phosphate.

Nickel film control. Recognition of the composition of a metal film on an object, according to L. Loviton (1886), can be carried out by heating the object in the external flame of a Bunsen burner: the nickel film turns blue, receives a black reflection and remains intact; silver does not change in the flame, but blackens when treated with a dilute solution of ammonium sulfide; finally, the tin coating quickly turns gray-yellow to gray and disappears when treated with the indicated reagent. Checking the quality of the nickel film on iron and copper in relation to pores and flaws can be done using the so-called. ferroxyl test and with particular convenience using ferroxyl paper coated with agar-agar gel with potassium ferric bluesulfide and sodium chloride. Apply wetted to the surface to be tested and after 3-5 minutes. fixed in water, this paper gives a documentary image of the smallest pores, which can be. saved.

Nickel recovery from old products. Removal of nickel plating from products made of iron and other non-amalgamated metals is carried out in the following ways: a) mercury vapor under vacuum or under ordinary pressure; b) heating scraps with sulfur, after which the metal layer is easily removed with hammers; c) heating scraps with substances that release sulfur at high temperature) when suddenly cooled, the nickel film jumps off; d) treatment with sulfuric or nitric acid heated to 50-60°C; iron goes into solution, and nickel remains almost undissolved; however, despite its simplicity, this method is of little use, since the obtained nickel still retains a significant iron content, which is not removed even during repeated treatment with acid (T. Fleitman); e) prolonged heating with access to air or water vapor, after which the trimmings are subjected to mechanical shocks and the nickel rebounds; e) electrolytic dissolution: an iron plated with nickel is made an anode in a bath containing ammonium carbonate; if the coating consists of a nickel alloy, then it is necessary to regulate the voltage, and at 0.5 V copper is deposited, and at a voltage greater than 2 V - nickel; in this process, iron is not corroded; g) iron or steel scraps are made an anode in a bath of an aqueous solution of sodium nitrate, while the cathode consists of a carbon stick; voltage should not exceed 20 V; h) Nickel is removed from zinc mugs by electrolysis of objects made with an anode in 50° sulfuric acid; an acid of this concentration has the property of dissolving only nickel, silver and gold, but not other metals, if there is a current; voltage applied 2-5V; iron sheets serve as cathodes, on which nickel is deposited in the form of dust; zinc does not dissolve, even though the circles remain in the electrolyte for a long time.

You can find the prices for nickel plating work at.

The application of nickel, as well as copper, is one of the mandatory procedures in preparing the product for the target top coat. There are many electrolytes for nickel deposition. It differs in methods of application, modes, coating quality and compositions. If you decide to do electroplating, you can't do without nickel plating.
Nickel itself is not often a target coating. As an anti-corrosion coating, it is not the best candidate, in this case zinc and chromium are more suitable, due to their chemical properties and the ability to "pull" the oxidation of rust-prone iron onto itself. how decorative coating Nickel plating is used more often, but due to its chemical instability, if it is necessary to apply the color of the "white" metal, plating with palladium or rhodium is more often chosen.

Our company uses galvanic nickel and chemical (immersion) nickel.
The simplest solution for nickel plating -

Acid solution (sublayer) nickel plating.

Acid nickel electrolyte is used as the first metal coating after cleaning and polishing the product. It can be considered a "glue" or a base, on which we will then put all the other metals. The thickness of the coating from such a solution does not exceed 1 µm, and the deposition rate is 1–2 µm/min. The exposure time in the acid nickel plating bath is not more than 1 minute. This is due to the fact that acid nickel gives brittle and dark precipitates at large thicknesses. But, nevertheless, it is necessary to put a thin layer of acid nickel. Some components of its composition provide micro-destruction of the surface for high-quality adhesion of the coating, however, by applying a thin layer of fresh nickel, we provide good adhesion for the next coating with copper or shiny nickel. Acid nickel electrolyte is very stable over time and resistant to contamination.

Bright nickel electrolyte.

Bright nickel electrolyte is used for micro leveling of the product surface. Compared to shiny copper, it gives less mirror-like precipitation. The rate of increase in thickness and the operating current density are also much lower, but this electrolyte is necessary for finishing products. It is necessarily used to obtain finishing deposits up to 15 microns thick. Or, with a coating thickness of 3-6 microns, as a high-quality substrate for electroplating or immersion gold.
Highly good results this solution demonstrates in drum and bell baths.

Electrolyte of chemical (immersion) nickel plating.

Chemical nickel plating is used in the processing of complex profile products. Works without application of external current. Uniform build-up of unstressed nickel at all points on the product's surface provides a hard, semi-shiny finish. Often this solution is used to protect against corrosion by growing nickel in a thickness of 6-30 microns. The use of chemical nickel plating is limited to the source material of the part. Chemical nickel plating is a hot solution, which does not always allow it to be used for plastics. Also, in the course of work, chemical nickel can deposit metal in the volume of liquid, and not just on the part, i.e. it may turn out that the entire volume of the solution is disposable.
We use several types of chemical nickel plating: alkaline and acid. Their principle of operation is the same, the quality of the coating, compositions and mode of operation differ significantly. Which chemical nickel solution to use depends on the product.
In addition to the listed types of nickel plating, there is also a solution of black nickel.

Black nickel.

Black nickel is the blackest plating that can be obtained by electroplating. Black chrome, black rhodium, black ruthenium are all dark gray finishes. Really black plating - only black nickel. If we consider the composition of this coating, this is not a completely nickel deposit; to obtain a dark coating, additional components are introduced into the solution of nickel salts. If you want to get black, this is your option. If black nickel has one huge minus: this coating is not at all resistant to abrasion. So much so that if you pick up black nickel-plated items several times, the plating can be erased. So the most beautiful black color of all electroplated coatings must be protected with varnish. Or put it on a shelf and admire the perfection of black nickel from afar.
There are several other types of electroplated nickel. They are not used all the time, but only as needed. The listed line of baths for nickel plating copes with the main tasks.

If you need to navigate the prices for nickel plating, you can use the table below, while remembering that each product before applying electroplating, must be inspected by the technologist and the terms of reference for the coating must be approved by the customer.

Prices for nickel-plated products to order:

Examples of nickel plating products:

Nickel plating of Sochi 2014 coins

Coins "Sochi 2014", nickel plated shiny 3 microns. The cost of covering 1 coin is 12 rubles (lot of 2000 pieces).

If you have any questions about nickel plating, we will be happy to answer them by phone or by e-mail.

Properties and applications of the coating. The basis of the chemical nickel plating process is the reduction reaction of nickel from aqueous solutions of its salts with sodium hypophosphite. Industrial applications have received methods for the deposition of Nickel from alkaline and acidic solutions. The deposited coating has a semi-brilliant metallic appearance, a fine crystalline structure, and is an alloy of nickel and phosphorus. The content of phosphorus in the sediment depends on the composition of the solution and ranges from 4-6% for alkaline to 8-10% for acidic solutions.

In accordance with the content of phosphorus, the physical constants of the nickel-phosphorus precipitate also change. Specific gravity its equal to 7.82-7.88 g / cm 3, melting point 890-1200 °, electrical resistivity is 0.60 ohm mm 2 /m. After heat treatment at 300-400°, the nickel-phosphorus coating hardness increases to 900-1000 kg/mm ​​2 . At the same time, the adhesion strength also increases many times over.

These properties of the nickel-phosphorus coating also determine its areas of application.

It is advisable to use it to cover parts of a complex profile, inner surface tubes and coils, for uniform coating of parts with very precise dimensions, to increase the wear resistance of rubbing surfaces and parts subjected to thermal effects, for example, for coating molds.

Parts made of ferrous metals, copper, aluminum and nickel are subjected to nickel-phosphorus coating.

This method is not suitable for nickel deposition on metals or coatings such as lead, zinc, cadmium and tin.

Nickel precipitation from alkaline solutions. Alkaline solutions are characterized by high stability, ease of adjustment, lack of tendency to violent and instantaneous precipitation of nickel powder (self-discharge phenomenon) and the possibility of their long-term operation without replacement.

The nickel deposition rate is 8-10 microns/hour. The process goes with intensive release of hydrogen on the surface of the Parts.

The preparation of the solution consists in dissolving each of the components separately, after which they are poured together into working bath, with the exception of sodium hypophosphite. It is poured only when the solution is heated to operating temperature and the parts are prepared for coating.

Preparation of the surface of steel parts for coating has no specific features.

After heating the solution to the operating temperature, it is corrected with a 25% ammonia solution to a stable blue color, sodium hypophosphite solution is added, the parts are hung and the coating is started without preliminary study. The solution is adjusted mainly with ammonia and sodium hypophosphite. With a large volume of the nickel plating bath and a high specific loading of parts, the solution is adjusted with ammonia directly from a cylinder with gaseous ammonia, with a continuous supply of gas to the bottom of the bath through a rubber tube.

A solution of sodium hypophosphite for the convenience of adjustment is prepared with a concentration of 400-500 g / l.

Nickel chloride solution is usually prepared for correction together with ammonium chloride and sodium citrate. For this purpose, it is most advisable to use a solution containing 150 g/l nickel chloride, 150 g/l ammonium chloride and 50 g/l sodium citrate.

The specific consumption of sodium hypophosphite per 1 dm 2 of the coating surface, with a layer thickness of 10 microns, is about 4.5 g, and nickel, in terms of metal, is about 0.9 g.

The main problems in the chemical deposition of Nickel from alkaline solutions are given in Table. eight.

Deposition of Nickel from Acid Solutions. Unlike alkaline solutions, acidic solutions are characterized by a wide variety of additives to solutions of nickel and hypophosphite salts. So, for this purpose, sodium acetate, succinic, tartaric and lactic acids, Trilon B and others can be used. organic compounds. Among the many compositions, below is a solution with the following composition and precipitation regime:

The pH value should be adjusted with a 2% sodium hydroxide solution. The nickel deposition rate is 8-10 microns/hour.

Overheating the solution above 95° can lead to self-discharge of nickel with an instant dark spongy precipitate and the solution splashing out of the bath.

The solution is adjusted according to the concentration of its constituent components only until 55 g/l of sodium phosphite NaH 2 PO 3 is accumulated in it, after which nickel phosphite can precipitate out of the solution. Upon reaching the specified concentration of phosphite, the nickel solution is drained and replaced with a new one.

heat treatment. In cases where nickel is applied to increase surface hardness and wear resistance, the parts are heat treated. At high temperatures, the nickel-phosphorus precipitate forms a chemical compound, which causes a sharp increase in its hardness.

The change in microhardness depending on the heating temperature is shown in Fig. 13. As can be seen from the diagram, the greatest increase in hardness occurs in the temperature range of 400-500 °. When choosing temperature regime it should be borne in mind that for a number of steels that have been quenched or normalized, high temperatures not always allowed. In addition, heat treatment carried out in air causes tempering colors on the surface of parts, ranging from golden yellow to purple. For these reasons, the heating temperature is often limited within 350-380°. It is also necessary that the nickel-plated surfaces be clean before laying in the furnace, since any contamination is detected after heat treatment very intensively and their removal is possible only by polishing. The heating time is 40-60 min. is sufficient.

Equipment and accessories. The main task in the manufacture of equipment for chemical nickel plating is the choice of bath linings that are resistant to acids and alkalis and heat conductive. For experimental work and for coating small parts, porcelain and steel enameled baths are used.

When coating large items in baths with a capacity of 50-100 liters or more, enameled tanks with enamels resistant to strong nitric acid are used. Some factories use steel cylindrical baths lined with a coating consisting of glue No. 88 and powdered chromium oxide, taken in equal weight quantities. Chromium oxide can be replaced with emery micropowders. The coating is produced in 5-6 layers with intermediate air drying.

At the Kirov Plant, for this purpose, the lining of cylindrical baths with removable plastic covers is successfully used. If it is necessary to clean the baths, the solutions are pumped out with a pump, and the covers are removed and treated in nitric acid. Carbon steel should be used as the material for hangers and baskets. Separate sections of parts and suspensions are insulated with perchlorovinyl enamels or plastic compounds.

To heat the solution, electric heaters should be used with heat transfer through a water jacket. Heat treatment of small parts is carried out in thermostats. For large products, shaft furnaces with automatic temperature control are used.

Nickel plating of stainless and acid-resistant steels. Nickel plating is carried out to increase surface hardness and wear resistance, as well as to protect against corrosion in those aggressive environments in which these steels are unstable.

For the adhesion of the nickel-phosphorus layer to the surface of high-alloy steels, the method of preparation for coating is of decisive importance. So, for stainless steel grade 1×13 and the like, surface preparation consists in its anodic treatment in alkaline solutions. The parts are mounted on carbon steel suspensions, using, if necessary, internal cathodes, hung in a bath with a 10-15% caustic soda solution and anode treated at an electrolyte temperature of 60-70 ° and an anode current density of 5-10 A / dm 2 for 5-10 minutes. until a uniform brown coating without metal gaps is formed. Then the parts are washed in cold running water, decapitated in hydrochloric acid (sp. weight 1.19), diluted twice, at a temperature of 15-25 ° for 5-10 seconds. After washing in cold running water, the parts are hung in a chemical nickel plating bath in an alkaline solution and plated in the usual way to a given layer thickness.

For parts made of acid-resistant steel type IX18H9T, anodic treatment should be carried out in a chromic acid electrolyte with the following composition and process mode:

After anodic treatment, the parts are washed in cold running water, decapitated in hydrochloric acid, as indicated for stainless steel, and hung in a nickel plating bath.

Nickel plating of non-ferrous metals. To deposit nickel on the previously deposited nickel layer, the parts are degreased and then decapitated in a 20-30% hydrochloric acid solution for 1 minute, after which they are hung in a bath for chemical nickel plating. Parts made of copper and its alloys are nickel-plated in contact with a more electronegative metal, such as iron or aluminum, using wire or pendants made of these metals for this purpose. In some cases, for a deposition reaction to occur, it is sufficient to create a short-term contact of an iron rod with the surface of a copper part.

For nickel plating of aluminum and its alloys, parts are etched in alkali, brightened in nitric acid, as is done before, with all types of coatings, and subjected to a double zincate treatment in a solution containing 500 g/l of sodium hydroxide and 100 g/l of zinc oxide, at a temperature 15-25°. The first immersion lasts 30 seconds, after which the precipitate of contact zinc is etched in dilute nitric acid, and the second immersion is 10 seconds, after which the parts are washed in cold running water and nickel plated in a bath with an alkaline nickel phosphorus solution. The resulting coating is very loosely bound to aluminum, and to increase the adhesion strength, the parts are heated by immersing them in lubricating oil at a temperature of 220-250 ° for 1-2 hours.

After heat treatment, the parts are degreased with solvents and, as necessary, wiped, polished or subjected to other types of machining.

Nickel plating of cermets and ceramics. Technological process Nickel plating of ferrites consists in the following operations: parts are degreased in a 20% solution of soda ash, washed with hot distilled water and pickled for 10-15 minutes. in an alcoholic solution of hydrochloric acid with a ratio of components 1:1. Then the parts are again washed with hot distilled water while cleaning the sludge with hair brushes. A solution of palladium chloride with a concentration of 0.5-1.0 g/l and a pH of 3.54:0.1 is applied to the coated surfaces of the parts with a brush. After air drying, the application of palladium chloride is repeated once more, dried and immersed for preliminary nickel plating in a bath with an acidic solution containing 30 g/l of nickel chloride, 25 g/l of sodium hypophosphite and 15 g/l of sodium succinic acid. For this operation, it is necessary to maintain the temperature of the solution within 96-98° and pH 4.5-4.8. Then the parts are washed in distilled hot water and nickel-plated in the same solution, but at a temperature of 90 °, until a layer 20-25 microns thick is obtained. After that, the parts are boiled in distilled water, copper-plated in a pyrophosphate electrolyte until a layer of 1-2 microns is obtained, after which they are subjected to acid-free soldering. The adhesion strength of the nickel-phosphorus coating with the ferrite base is 60-70 kg/cm 2 .

Besides, chemical nickel plating exposed different kinds ceramics, such as ultra-porcelain, quartz, steatite, piezoceramics, ticond, thermocond, etc.

Nickel plating technology consists of the following operations: parts are degreased with alcohol, washed in hot water and dried.

After that, for parts made of ticond, thermocond and quartz, their surface is sensitized with a solution containing 10 g/l of tin chloride SnCl 2 and 40 ml/l of hydrochloric acid. This operation is performed with a brush or by rubbing with a wooden washer moistened with a solution, or by immersing the parts in a solution for 1-2 minutes. Then the surface of the parts is activated in a solution of palladium chloride PdCl 2 2H 2 O.

For ultra-porcelain, a heated solution is used with a concentration of PdCl 2 ·2H 2 O 3-6 g / l and with an immersion time of 1 sec. For tikond, thermocond and quartz, the concentration decreases to 2-3 g / l with an increase in exposure from 1 to 3 minutes, after which the parts are immersed in a solution containing calcium hypophosphite Ca (H 2 PO 2) 2 in an amount of 30 g / l, without heating, for 2-3 minutes.

Parts made of ultra-porcelain with an activated surface are hung for 10-30 seconds. into a pre-nickel plating bath with an alkaline solution, after which the parts are washed and hung again in the same bath to build up a layer of a given thickness.

Parts made of tikond, thermocond and quartz after treatment in calcium hypophosphite are nickel-plated in acidic solutions.

Chemical deposition of nickel from carbonyl compounds. When heating vapors of nickel tetracarbonyl Ni(CO) 4 at a temperature of 280°±5, the reaction of thermal decomposition of carbonyl compounds occurs with the deposition of metallic nickel. The precipitation process takes place in a hermetically sealed container at atmospheric pressure. The atmosphere consists of 20-25% (by volume) nickel tetracarbonyl and 80-75% carbon monoxide CO. The admixture of oxygen in the gas is admissible not more than 0.4%. For uniform deposition, gas circulation should be created at a feed rate of 0.01-0.02 m/s and reversal of the feed direction every 30-40 seconds. . Preparation of parts for coating is to remove oxides and grease. The nickel deposition rate is 5-10 microns/min. The deposited nickel has a matte surface, a dark gray tint, a fine crystalline structure, a hardness of 240-270 Vickers, and a relatively low porosity.

The adhesion strength of the coating to the metal of the products is very low, and to increase it to satisfactory values, heat treatment at 600-700°C for 30-40 minutes is necessary.