Nickel-plated coatings have a number of valuable properties: they are well polished, acquiring a beautiful long-lasting mirror shine, they are durable and protect the metal well from corrosion.
The color of nickel coatings is silver-white with a yellowish tint; They are easily polished, but become dull over time. The coatings are characterized by a fine-crystalline structure, good adhesion to steel and copper substrates, and the ability to passivate in air.
Nickel plating is widely used as a decorative coating for parts of lamps intended for lighting public and residential premises.
To coat steel products, nickel plating is often carried out over an intermediate sublayer of copper. Sometimes a three-layer nickel-copper-nickel coating is used. In some cases, a thin layer of chromium is applied to the nickel layer to form a nickel-chrome coating. Nickel is applied to parts made of copper and copper-based alloys without an intermediate sublayer. The total thickness of two and three-layer coatings is regulated by mechanical engineering standards; it is usually 25–30 microns.
On parts intended to operate in humid tropical climates, the coating thickness must be at least 45 microns. In this case, the regulated thickness of the nickel layer is no less than 12–25 microns.
To obtain a shiny finish, nickel-plated parts are polished. Recently, bright nickel plating has been widely used, which eliminates the labor-intensive operation of mechanical polishing. Bright nickel plating is achieved by introducing brightening agents into the electrolyte. However, the decorative qualities of mechanically polished surfaces are higher than those obtained by bright nickel plating.
Nickel deposition occurs with significant cathodic polarization, which depends on the temperature of the electrolyte, its concentration, composition and some other factors.
Electrolytes for nickel plating are relatively simple in composition. Currently, sulfate, hydrofluoride and sulfamite electrolytes are used. Lighting factories use exclusively sulfate electrolytes, which make it possible to work with high current densities and thus obtain coatings High Quality. The composition of these electrolytes includes salts containing nickel, buffer compounds, stabilizers and salts that promote the dissolution of the anodes.
The advantages of these electrolytes are the non-scarcity of components, high stability and low aggressiveness. Electrolytes allow a high concentration of nickel salt in their composition, which makes it possible to increase the cathode current density and, consequently, increase the productivity of the process.
Sulfate electrolytes have high electrical conductivity and good dissipation ability.
The following electrolyte composition, g/l, is widely used:
NiSO4 7H2O240–250
*Or NiCl2·6H2O – 45 g/l.
Nickel plating is carried out at a temperature of 60°C, pH=5.6÷6.2 and a cathodic current density of 3–4 A/dm2.
Depending on the composition of the bath and its operating mode, coatings with varying degrees of gloss can be obtained. For these purposes, several electrolytes have been developed, the compositions of which are given below, g/l:
for matte finish:
NiSO4 7H2O180–200
Na2SO4 10H2O80–100
Nickel plating at a temperature of 25–30°C, at a cathodic current density of 0.5–1.0 A/dm2 and pH=5.0÷5.5;
for a semi-gloss finish:
Nickel sulfate NiSO4 7H2O200–300
Boric acid H3BO330
2,6–2,7-Disulfonaphthalic acid5
Sodium fluoride NaF5
Sodium chloride NaCl7–10
Nickel plating is carried out at a temperature of 20–35°C, cathodic current density of 1–2 A/dm2 and pH=5.5÷5.8;
for a shiny finish:
Nickel sulfate (hydrate) 260–300
Nickel chloride (hydrate) 40–60
Boric acid30–35
Saccharin0.8–1.5
1,4-butynediol (100% equivalent) 0.12–0.15
Phthalimide0.08–0.1
Operating temperature of nickel plating is 50–60°C, electrolyte pH 3.5–5, cathode current density with intensive stirring and continuous filtration 2–12 A/dm2, anodic current density 1–2 A/dm2.
A special feature of nickel plating is a narrow range of electrolyte acidity, current density and temperature.
To maintain the composition of the electrolyte within the required limits, buffer compounds are introduced into it, which most often use boric acid or a mixture of boric acid and sodium fluoride. Some electrolytes use citric, tartaric, acetic acid or their alkaline salts as buffer compounds.
A special feature of nickel coatings is their porosity. In some cases, pinpoint spots, so-called “pitting,” may appear on the surface.
To prevent pitting, intensive air mixing of the baths and shaking of the pendants with parts attached to them are used. The reduction of pitting is facilitated by the introduction of surface tension reducers or wetting agents into the electrolyte, which are sodium lauryl sulfate, sodium alkyl sulfate and other sulfates.
The domestic industry produces a good anti-pitting detergent "Progress", which is added to the bath in an amount of 0.5 mg/l.
Nickel plating is very sensitive to foreign impurities that enter the solution from the surface of parts or due to anodic dissolution. When nickel plating steel parts
When coating copper-based alloys, the solution becomes clogged with iron impurities, and when coating copper-based alloys, it becomes clogged with its impurities. Removal of impurities is carried out by alkalizing the solution with nickel carbonate or hydroxide.
Organic contaminants that contribute to pitting are removed by boiling the solution. Sometimes tinting of nickel-plated parts is used. This produces colored surfaces with a metallic sheen.
Toning is carried out chemically or electrochemically. Its essence lies in the formation of a thin film on the surface of the nickel coating, in which light interference occurs. Such films are produced by applying organic coatings several micrometers thick to nickel-plated surfaces, for which the parts are treated in special solutions.
Black nickel coatings have good decorative qualities. These coatings are obtained in electrolytes, to which zinc sulfates are added in addition to nickel sulfates.
The composition of the electrolyte for black nickel plating is as follows, g/l:
Nickel sulfate40–50
Zinc sulfate20–30
Rhodane potassium25–32
Ammonium sulfate12–15
Nickel plating is carried out at a temperature of 18–35°C, cathodic current density of 0.1 A/dm2 and pH=5.0÷5.5.
Chrome coatings have high hardness and wear resistance, a low coefficient of friction, are resistant to mercury, firmly adhere to the base metal, and are also chemical and heat resistant.
In the manufacture of lamps, chrome plating is used to obtain protective and decorative coatings, and also as reflective coatings in the manufacture of mirror reflectors.
Chrome plating is carried out over a previously applied copper-nickel or nickel-copper-nickel sublayer. The thickness of the chromium layer with such a coating usually does not exceed 1 micron. In the manufacture of reflectors, chrome plating is currently being replaced by other coating methods, but in some factories it is still used for the manufacture of reflectors for mirror lamps.
Chrome has good adhesion to nickel, copper, brass and other deposited materials, but poor adhesion is always observed when depositing other metals onto a chrome coating.
A positive property of chromium coatings is that parts become shiny directly in galvanic baths; this does not require mechanical polishing. Along with this, chrome plating differs from other galvanic processes in that it has more stringent requirements for the operating conditions of the baths. Minor deviations from the required current density, electrolyte temperature and other parameters inevitably lead to deterioration of coatings and massive defects.
The dissipative ability of chromium electrolytes is low, which leads to poor coverage of internal surfaces and recesses of parts. To increase the uniformity of coatings, special suspensions and additional screens are used.
For chrome plating, solutions of chromic anhydride with the addition of sulfuric acid are used.
Three types of electrolytes have found industrial application: diluted, universal and concentrated (Table 1). To obtain decorative coatings and to obtain reflectors, concentrated electrolyte is used. When chrome plating, insoluble lead anodes are used.
Table 1 - Compositions of electrolytes for chrome plating
During operation, the concentration of chromic anhydride in the baths decreases, therefore, to restore the baths, daily adjustments are made by adding fresh chromic anhydride to them.
Several formulations of self-regulating electrolytes have been developed, in which the concentration ratio is automatically maintained
.The composition of this electrolyte is as follows, g/l:
Chromium plating is carried out at a cathodic current density of 50–80 A/dm2 and a temperature of 60–70°C.
Depending on the relationship between temperature and current density, different types of chrome coating can be obtained: milky shiny and matte.
Chrome/Nickel
(post too old to reply)
2005-03-27 19:01:08 UTC
Nickel plating?
I know that both are used to coat metal surfaces to
make them shiny and protect them from corrosion.
Cost difference?
Oleg ICQ#168343240
The one who gets up early bothers everyone
Leizer A. Karabin
2005-03-28 04:58:10 UTC
Good afternoon, Oleg light Antoshkiv!
Actually, I just went out Monday March 28 2005 00:01,
here I hear Oleg Antoshkiv saying All (well, I butted in, of course):
OA> Question purely out of curiosity: what is the difference between chrome plating and
OA> nickel plating?
I hope this question is rhetorical. Or explain.
OA> I know that both are used for coating metal
OA> surfaces to make them shiny and protect them from corrosion.
OA> How to distinguish a chrome-plated surface from a nickel-plated one by eye?
Nickel is slightly yellowish, chrome is slightly bluer.
OA> What is the difference in mechanical strength and chemical resistance?
For improvised and household chemicals, both are absolutely stable.
OA> Cost difference?
Chrome plating is definitely more expensive.
OA> Is the coating technology the same?
Very different. For example, the traditional technology of chrome plating bumpers
this is nickel - copper - nickel - glitter. nickel - chrome on steel. or without the first
nickel sublayer if you obtain permission for copper from cyanide el.
If you thought that there were just single-layer
decorative anti-corrosion coatings, then only Chinese-underground watches.
Half a micron of chrome or gold on bronze is enough for a couple of weeks of wear.
OA> Is there a difference which metals can be coated with both?
The difference is in technology, but in general any can be covered with anything.
Why do you need to find out what is where, or did you get ready yourself? The last "M-uh, no
I advise you, they’ll eat it!” (C)
For this forever and so on. Leizer (ICQ 62084744)
2005-03-28 08:07:29 UTC
Greetings, Oleg!
Monday March 28 2005 00:01, Oleg Antoshkiv -> All:
OA> Question purely out of curiosity: what is the difference between chrome plating and
OA> nickel plating?
different metals
OA> I know that both are used for coating
OA>
OA> corrosion. How to distinguish a chrome surface by eye
OA> nickel plated?
Nickel is usually just white, and chrome plating may change color, although
usually slightly purple.
OA> What is the difference in mechanical strength and chemical resistance?
Chrome plating gives a harder coating than nickel, chemically chromium
continues to protect the base metal (if it is steel) with minor damage
coating, in the case of nickel, corrosion only accelerates when the coating is damaged.
OA> Cost difference?
who the hell knows
OA> Is the coating technology the same?
At least on steel products, chromium is deposited directly, and nickel
through the substrate (copper).
OA> Is there a difference which metals can be coated with both?
Best regards, Sergey Din.
Andrew Mitrohin
2005-03-28 13:26:07 UTC
*_Be healthy_*, /_Oleg_/!
OA> Question purely out of curiosity: what is the difference between chrome plating and
OA> nickel plating? I know that both are used for coating
OA> metal surfaces to make them shiny and protect them from
OA> corrosion.
OA> How to distinguish a chrome-plated surface from a nickel-plated one by eye
OA> ?
The color is different.
OA> What is the difference in mechanical strength and chemical resistance?
Chrome is better in these parameters.
OA> Cost difference?
Before plating with nickel, the metal is coated with copper and polished.
Before plating with chrome, the metal is first coated with copper, then nickel and
then chrome. Then the coating is durable.
OA> Is the coating technology the same?
Different, it’s better to forget about chrome at home. Chromic anhydride is used
which is very toxic.
OA> Is there a difference which metals can be coated with both?
If I'm not mistaken, everything depends on the activity of the metal.
/With respect/, _/Andrew/_...
- [Russian rock music] -
None of the home craftsmen has ever faced the need to nickel-plate or chrome-plate this or that part. What do-it-yourselfer hasn’t dreamed of installing a “non-working” bushing with a hard, wear-resistant surface obtained by saturating it with boron in a critical component. But how to do at home what is usually done at specialized enterprises using chemical-thermal and electrochemical processing of metals. You won’t build gas and vacuum furnaces at home, or construct electrolysis baths. But it turns out that there is no need to build all this at all. It is enough to have some reagents on hand, an enamel pan and, perhaps, blowtorch, and also know the recipes of “chemical technology”, with the help of which metals can also be copper-plated, cadmium-plated, tin-plated, oxidized, etc.
So, let's begin to get acquainted with the secrets of chemical technology. Please note that the content of components in the solutions given is usually given in g/l. If other units are used, a special disclaimer follows.
Preparatory operations
Before applying paints, protective and decorative films, and also before covering them with other metals, it is necessary to carry out preparatory operations, that is, remove contamination from these surfaces of different nature. Please note that the final result of all work greatly depends 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 is no rust, scale or other foreign products on their surface.
Using degreasing, oil and grease films are removed from the surface of parts. For this purpose, aqueous solutions of certain chemical reagents 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 at the same time they are toxic and flammable.
Aqueous solutions. Degreasing of metal parts in aqueous solutions is carried out in enamel containers. Pour in water, dissolve chemicals in it and place on low heat. When the desired temperature is reached, the parts are loaded into the solution. During processing, the solution is stirred. Below are the compositions of 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 minutes.
Liquid glass - 5...10, caustic soda - 100...150, soda ash - 30...60. Solution temperature - 70...80°C, processing time - 5...10 minutes.
Liquid glass - 35, trisodium phosphate - 3...10. Solution temperature - 70...90°C, processing time - 10...20 minutes.
Liquid glass - 35, trisodium phosphate - 15, drug - emulsifier OP-7 (or OP-10) -2. Solution temperature - 60-70°C, processing time - 5...10 minutes.
Liquid glass - 15, preparation OP-7 (or OP-10) -1. Solution temperature - 70...80°C, processing time - 10...15 minutes.
Soda ash - 20, potassium chromium - 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, treatment 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°C, processing time - 5...10 minutes.
Trisodium phosphate - 80...100. Solution temperature - 80...90°C, processing time - 30...40 minutes.
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°C, processing time - 3...5 minutes.
Soda ash - 20...25, trisodium phosphate - 20...25, preparation OP-7 (or OP-10) - 5...7. Temperature - 70...80°C, processing time - 10...20 minutes.
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°C, processing time - 5 minutes.
Liquid glass - 30...50, soda ash - 30....50, kerosene - 30...50, preparation OP-7 (or OP-10) - 2...3. Solution temperature - 60-70°C, processing time - 1...2 minutes.
Organic solvents
The most commonly used organic solvents are B-70 gasoline (or “gasoline for lighters”) and acetone. However, they have a significant drawback - they are easily flammable. Therefore, recently they have been replaced by non-flammable solvents such as trichlorethylene and perchlorethylene. Their dissolving ability is much higher than that of gasoline and acetone. Moreover, these solvents can be safely heated, which greatly speeds up the degreasing of metal parts.
Degreasing the surface of metal parts using organic solvents is carried out in the following sequence. The parts are loaded into a container with solvent and kept for 15...20 minutes. Then the surface of the parts is wiped directly in the solvent with a brush. After this treatment, the surface of each part is carefully treated with a swab moistened with 25% ammonia (you must work with rubber gloves!).
All degreasing work with organic solvents is carried out in a well-ventilated area.
Cleaning
In this section, the process of cleaning carbon deposits from internal combustion engines will be considered as an example. As is known, carbon deposits are asphalt-resinous substances that form difficult-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 - 3 hours.
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 bichromate - 5, laundry soap - 10, soda ash - 20. Solution temperature - 85...95 ° C, processing time - up to 3 hours.
Soda ash - 10, potassium bichromate - 5, laundry soap - 10. Solution temperature - 80...95 ° C, processing time - up to 3 hours.
Etching
Pickling (as a preparatory operation) allows you to remove contaminants (rust, scale and other corrosion products) from metal parts that are firmly adhered to their surface.
The main purpose of etching is to remove corrosion products; in this case, the base metal should not be etched. To prevent metal etching, special additives are added to the solutions. Good results are obtained with the use of small amounts of hexamethylenetetramine (urotropine). To all solutions for etching ferrous metals, add 1 tablet (0.5 g) of hexamine per 1 liter of solution. In the absence of urotropine, it is replaced with the same amount of dry alcohol (sold in sporting goods stores as fuel for tourists).
Due to the fact that in recipes for pickling they 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; orthophosphoric acid - 1.7; acetic acid - 1.05.
Compositions of etching solutions
For ferrous metals
Sulfuric acid - 90...130, hydrochloric acid - 80...100. Solution temperature - 30...40°C, processing time - 0.5...1.0 hours.
Sulfuric acid - 150...200. Solution temperature - 25...60°C, processing time - 0.5...1.0 hours.
Hydrochloric acid - 200. Solution temperature - 30...35°C, processing time - 15...20 minutes.
Hydrochloric acid - 150...200, formalin - 40...50. Solution temperature 30...50°C, processing time 15...25 minutes.
Nitric acid - 70...80, hydrochloric acid - 500...550. Solution temperature - 50°C, processing time - 3...5 minutes.
Nitric acid - 100, sulfuric acid - 50, hydrochloric acid - 150. Solution temperature - 85°C, treatment time - 3...10 minutes.
Hydrochloric acid - 150, orthophosphoric acid - 100. Solution temperature - 50°C, processing time - 10...20 minutes.
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 allow them to be painted with any paint without 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 minutes.
Orthophosphoric acid - 35, butyl alcohol - 5, water - 60. Solution temperature - 40...60°C, processing time - 30...35 minutes.
After etching 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°C, processing time - 5...10 minutes.
Sulfuric acid - 150, potassium dichromate - 50. Solution temperature - 25.35 ° C, processing time - 5...15 minutes.
Trilon B-100. Solution temperature - 18...25°C, processing time - 5...10 minutes.
Chromic anhydride - 350, sodium chloride - 50. Solution temperature - 18...25°C, processing time - 5...15 minutes.
For aluminum and its alloys
Caustic soda -50...100. Solution temperature - 40...60°C, processing time - 5...10 s.
Nitric acid - 35...40. Solution temperature - 18...25°C, processing time - 3...5 s.
Caustic soda - 25...35, soda ash - 20...30. Solution temperature - 40...60°C, processing time - 0.5...2.0 minutes.
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 surfaces 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 specific case in certain units (g/l, percentage, parts)
Nitric acid - 2.-.4, hydrochloric acid 2...5, Phosphoric acid - 15...25, the rest is water. Solution temperature - 70...80°C, processing time - 1...10 minutes. Contents of components - in% (by volume).
Sulfuric acid - 0.1, acetic acid - 25, hydrogen peroxide (30%) - 13. Solution temperature - 18...25°C, treatment 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°C, processing 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°C, processing time - 2...3 minutes. Content of components - in g/l.
Nitric acid - 4...5, hydrochloric acid - 3...4, Phosphoric acid - 20..30, methyl orange - 1..1.5, the rest is water. Solution temperature - 18...25°C, processing time - 5...10 minutes. Contents of components - in% (by weight).
Nitric acid - 30...90, potassium ferric sulfide (yellow blood salt) - 2...15 g/l, preparation OP-7 - 3...25, hydrochloric acid - 45..110, orthophosphoric acid - 45. ..280.
Solution temperature - 30...40°C, processing time - 15...30 minutes. Content of components (except for yellow blood salt) - in pl/l.
The latter composition is suitable for polishing cast iron and any steels.
For copper
Nitric acid - 900, sodium chloride - 5, soot - 5. Solution temperature - 18...25°C, treatment time - 15...20 s. Component content - g/l.
Attention! Sodium chloride is introduced into 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, treatment time - 1...2 min. Component content - in ml.
Nitric acid 500, sulfuric acid - 250, sodium chloride - 10. Solution temperature - 18...25°C, treatment time - 10...20 s. Content of components - in g/l.
For brass
Nitric acid - 20, hydrochloric acid - 0.01, acetic acid - 40, orthophosphoric acid - 40. Mixture temperature - 25...30 ° C, processing time - 20...60 s. Component content - in ml.
Copper sulfate (copper sulfate) - 8, sodium chloride - 16, acetic acid - 3, water - the rest. Solution temperature - 20°C, processing time - 20...60 minutes. Component content - in% (by weight).
For bronze
Phosphoric acid - 77...79, potassium nitrate - 21...23. Mixture temperature - 18°C, processing time - 0.5-3 minutes. Component content - 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. Contents of components (except sodium chloride) - in ml.
For nickel and its alloys (nickel silver and nickel silver)
Nitric acid - 20, acetic acid - 40, orthophosphoric acid - 40. Mixture temperature - 20°C, processing time - up to 2 minutes. Component content - in% (by weight).
Nitric acid - 30, acetic acid (glacial) - 70. Mixture temperature - 70...80°C, processing time - 2...3 s. 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 minutes. Contents of components - in parts (by volume).
Phosphoric acid - 60, sulfuric acid - 200, nitric acid - 150, urea - 5g. Mixture temperature - 100°C, processing time - 20 s. Content of components (except urea) - in ml.
Phosphoric acid - 70, sulfuric acid - 22, boric acid- 8. Mixture temperature - 95°C, processing time - 5...7 minutes. Contents of components - in parts (by volume).
Passivation
Passivation is the process of chemically creating an inert layer on the surface of a metal that prevents the metal itself from oxidizing. The process of passivation of the surface of metal products is used by minters when creating their works; craftsmen - in the manufacture of various crafts (chandeliers, sconces and other household items); sports fishermen passivate their homemade metal baits.
Compositions of solutions for passivation (g/l)
For ferrous metals
Sodium nitrite - 40...100. Solution temperature - 30...40°C, processing time - 15...20 minutes.
Sodium nitrite - 10...15, soda ash - 3...7. Solution temperature - 70...80°C, processing time - 2...3 minutes.
Sodium nitrite - 2...3, soda ash - 10, preparation OP-7 - 1...2. Solution temperature - 40...60°C, processing time - 10...15 minutes.
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 minutes.
Potassium dichromate - 150. Solution temperature - 60°C, processing time - 2...5 minutes.
For aluminum and its alloys
Orthophosphoric acid - 300, chromic anhydride - 15. Solution temperature - 18...25°C, processing time - 2...5 minutes.
Potassium dichromate - 200. Solution temperature - 20°C, “processing 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°C, 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 for car body treatments passenger cars before coating them with anti-corrosion and anti-wear compounds.
Compositions of solutions for phosphating (g/l)
For steel
Majef (manganese and iron phosphate salts) - 30, zinc nitrate - 40, sodium fluoride - 10. Solution temperature - 20°C, treatment time - 40 minutes.
Monozinc phosphate - 75, zinc nitrate - 400...600. Solution temperature - 20°C, processing time - 20...30 s.
Majef - 25, zinc nitrate - 35, sodium nitrite - 3. Solution temperature - 20°C, treatment time - 40 minutes.
Monoammonium phosphate - 300. Solution temperature - 60...80°C, processing time - 20...30 s.
Orthophosphoric acid - 60...80, chromic anhydride - 100...150. Solution temperature - 50...60°C, processing time - 20...30 minutes.
Orthophosphoric acid - 400...550, butyl alcohol - 30. Solution temperature - 50°C, processing time - 20 minutes.
Metal coating
Chemical coating of some metals with others is captivating due to the simplicity of the technological process. Indeed, if, for example, it is necessary to chemically nickel-plate any steel part, it is enough to have suitable enameled utensils and a heating source ( gas stove, Primus, etc.) and relatively scarce 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 can parts with complex profiles and internal cavities (pipes, etc.) be reliably nickel-plated. True, chemical nickel plating (and some other similar processes) is not without its drawbacks. The main one is that the adhesion of the nickel film to the base metal is not too strong. 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 with others.
Nickel plating
The chemical nickel plating process is based on the reduction of nickel from aqueous solutions of its salts using sodium hypophosphite and some other chemicals.
Chemically produced nickel coatings have an amorphous structure. The presence of phosphorus in nickel makes the film similar in hardness to a chromium film. Unfortunately, the adhesion of the nickel film to the base metal is relatively low. Thermal treatment of nickel films (low-temperature diffusion) consists of heating nickel-plated parts to a temperature of 400°C and holding them at this temperature for 1 hour.
If the parts coated with nickel are hardened (springs, knives, fishhooks, etc.), then at a temperature of 40°C they can be tempered, 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 a holding time of up to 3 hours. In this case, heat treatment also increases the hardness of the nickel coating.
All of the listed advantages of chemical nickel plating have not escaped the attention of technologists. They found them practical use(except for the use of decorative and anti-corrosion properties). Thus, with the help of chemical nickel plating, axes of various mechanisms, worms of thread-cutting machines, etc. are repaired.
At home, using nickel plating (chemical, of course!) you can repair parts of various household devices. The technology here is extremely simple. For example, the axis of some device was demolished. Then a layer of nickel is built up (in excess) on the damaged area. Then the working area of the axle is polished, bringing it to the desired size.
It should be noted that chemical nickel plating cannot be used to coat 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 process speed is higher. Another important feature of acidic solutions: they are less likely to self-discharge when the operating temperature is exceeded. (Self-discharge is the instantaneous precipitation of nickel into the solution with the latter splashing.)
Alkaline solutions have the main advantage of more reliable adhesion of the nickel film to the base metal.
And one last thing. 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 clean (designation on the label - C).
Before covering parts with any metal film, it is necessary to carry out special preparation of their surface.
The 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 pickled in one of the solutions listed below.
Compositions of solutions for pickling (g/l)
For steel
Sulfuric acid - 30...50. Solution temperature - 20°C, processing time - 20...60 s.
Hydrochloric acid - 20...45. Solution temperature - 20°C, processing time - 15...40 s.
Sulfuric acid - 50...80, hydrochloric acid - 20...30. Solution temperature - 20°C, 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, another treatment is carried out - the so-called zincate treatment. Below are solutions for zincate treatment.
For aluminum
Caustic soda - 250, zinc oxide - 55. Solution temperature - 20 C, processing time - 3...5 s.
Caustic soda - 120, zinc sulfate - 40. Solution temperature - 20°C, processing time - 1.5...2 minutes.
When preparing both solutions, first dissolve caustic soda separately in half of the water, and the zinc component in the other half. Then both solutions are poured together.
For cast aluminum alloys
Caustic soda - 10, zinc oxide - 5, Rochelle salt (crystalline hydrate) - 10. Solution temperature - 20 C, processing time - 2 minutes.
For wrought aluminum alloys
Ferric chloride (crystalline hydrate) - 1, caustic soda - 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, suitable for all metals (although there are some specifics). They are prepared in a certain sequence. So, all chemical reagents (except for sodium hypophosphite) are dissolved in water (enamel dishes!). Then the solution is heated to operating temperature and only after that sodium hypophosphite is dissolved and the parts are hung in the solution.
In 1 liter of solution you can nickel-plate a surface with an area of up to 2 dm2.
Compositions of solutions for nickel plating (g/l)
Nickel sulfate - 25, sodium succinate - 15, sodium hypophosphite - 30. Solution temperature - 90°C, pH - 4.5, film growth rate - 15...20 µm/h.
Nickel chloride - 25, sodium succinate - 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 ° C, 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 µm /h.
Nickel chloride - 45, ammonium chloride - 45, sodium citrate - 45, sodium hypophosphite - 20. Solution temperature - 90°C, pH - 8.5, growth rate - 18... 20 µm/h.
Nickel chloride - 30, ammonium chloride - 30, sodium succinate - 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 µm/ h.
Nickel sulfate - 30, ammonium sulfate - 30, sodium hypophosphite - 10. Solution temperature - 85°C, pH - 8.2...8.5, growth rate - 15...18 µm/h.
Attention! According to existing GOSTs, a single-layer nickel coating per 1 cm2 has several dozen through pores (to the base metal). Naturally, in the open air, a steel part coated with nickel will quickly become covered with a “rash” of rust.
In a modern car, for example, the bumper is covered with a double layer (an underlayer of copper, and on top - chrome) and even a triple layer (copper - nickel - chrome). But this does not save the part from rust, since according to GOST and triple coating there are several pores per 1 cm2. What to do? The solution is to treat the surface of the coating with special compounds that close the pores.
Wipe the part with nickel (or other) coating with a slurry of magnesium oxide and water and immediately immerse it in a 50% solution of hydrochloric acid for 1...2 minutes.
After heat treatment, dip 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 LPS (easily penetrating lubricant).
In the last two cases, excess fat (lubricant) is removed from the surface with gasoline after a day.
Large surfaces (bumpers, car moldings) are treated with fish oil as follows. 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 fishing in the sea. The same hooks treated with fish oil do not corrode for almost the entire summer sea fishing season.
Chrome plating
Chemical chromium plating allows you to obtain a coating on the surface of metal parts gray, which after polishing acquires the desired shine. Chrome fits well over nickel coating. The presence of phosphorus in chemically produced chromium significantly increases its hardness. Heat treatment for chrome coatings is necessary.
Below are practice-tested recipes chemical chrome 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 glycolic acid - 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 (replacement of sodium hypophosphite) - 50...75.
Solution temperature - 100°C, pH - 7.5...9, growth rate - 2...2.5 µm/h.
Boron nickel plating
The film of this dual alloy has increased hardness (especially after heat treatment), a high melting point, high wear resistance and significant corrosion resistance. All this allows the use of such coating in various responsible homemade structures. Below are recipes for solutions in which boronickel plating is carried out.
Compositions of solutions for chemical boronickeling (g/l)
Nickel chloride - 20, sodium hydroxide - 40, ammonia (25% solution): - 11, sodium borohydride - 0.7, ethylenediamine (98% solution) - 4.5. The solution temperature is 97°C, the growth rate is 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. The solution temperature is 97°C, the growth rate is 1.5 µm/h.
Caustic soda - 4...40, potassium metabisulfite - 1...1.5, sodium potassium 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.
Borocobaltation
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 cobaltation (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°C, pH - 12.5, growth rate - 3 µm/h.
Cobalt sulfate - 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 used outdoors.
It has been noted that chemically produced cadmium coatings adhere well to the base metal even without heat treatment.
Cadmium chloride - 50, ethylenediamine - 100. Cadmium must be in contact with the parts (suspension on cadmium wire, small parts are sprinkled with powdered cadmium). Solution temperature - 65°C, pH - 6...9, growth rate - 4 µm/h.
Attention! Ethylenediamine is the last to be dissolved in the solution (after heating).
Copper plating
Chemical copper plating is most often used in the manufacture printed circuit boards for radio electronics, in electroplating, for metallization of plastics, for double coating of some metals with others.
Compositions of solutions for copper plating (g/l)
Copper sulfate - 10, sulfuric acid - 10. Solution temperature - 15...25 ° C, growth rate - 10 µm/h.
Potassium sodium tartrate - 150, copper sulfate - 30, caustic soda - 80. Solution temperature - 15...25 ° C, growth rate - 12 µm/h.
Copper sulfate - 10...50, caustic soda - 10...30, Rochelle salt 40...70, formalin (40% solution) - 15...25. The solution temperature is 20°C, the growth rate is 10 µm/h.
Copper sulfate - 8...50, sulfuric acid - 8...50. The solution temperature is 20°C, the growth rate is 8 µm/h.
Copper sulfate - 63, potassium tartrate - 115, sodium carbonate - 143. Solution temperature - 20 C, growth rate - 15 µm/h.
Copper sulfate - 80...100, caustic soda - 80...,100, sodium carbonate - 25...30, nickel chloride - 2...4, Rochelle salt - 150...180, formalin (40% - nal solution) - 30...35. The solution temperature is 20°C, the growth rate is 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 iron sulfide (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 films of copper.
To improve the adhesion of the film to the base metal, heat treatment is used the same as for nickel.
Silvering
Silvering of metal surfaces is perhaps the most popular process among craftsmen, which they use in their activities. Dozens of examples can be given. For example, restoring the silver layer on cupronickel cutlery, silvering samovars and other household items.
For coiners, silvering, together with chemical coloring of metal surfaces (which will be discussed below), is a way to increase the artistic value of embossed paintings. Imagine a minted ancient warrior, whose chain mail and helmet are silvered.
The chemical silvering process itself 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 embossed paintings).
Composition of solutions for silver plating (g/l)
Silver chloride - 7.5, potassium iron sulfide - 120, potassium carbonate - 80. Working solution temperature - about 100°C. Processing time - until the desired thickness of the silver layer is obtained.
Silver chloride - 10, sodium chloride - 20, potassium tartrate - 20. Processing - in a boiling solution.
Silver chloride - 20, potassium ferric sulfide - 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 until the thickness of sour cream. 10...15 g of paste is dissolved in 1 liter of boiling water. Processing - in a boiling solution.
The parts are hung in silvering solutions on zinc wires (strips).
Processing time is determined visually. It should be noted here that brass is better silvered than copper. A fairly thick layer of silver must be applied to the latter so that the dark copper does not show through the coating layer.
One more note. Solutions with silver salts cannot be stored for a long time, as this can form explosive components. The same applies to all liquid pastes.
Compositions of pastes for silvering.
2 g of lapis pencil are 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% solution of sodium chloride is gradually added to the resulting solution until the precipitation.The curdled precipitate of silver chloride is filtered and thoroughly washed in 5...6 waters.
20 g of sodium thiosulfite are dissolved in 100 ml of water. Silver chloride is added to the resulting solution until it stops dissolving. The solution is filtered and tooth powder is added to it until it reaches the consistency of liquid sour cream. Rub (silver) the part with this paste using a cotton swab.
Lapis pencil - 15, citric acid (food grade) - 55, ammonium chloride - 30. Each component is ground into powder before mixing. Component content - in% (by weight).
Silver chloride - 3, sodium chloride - 3, sodium carbonate - 6, chalk - 2. 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 ground components are mixed. Using a wet swab, powdering it with a dry mixture of chemicals, rub (silver) the desired part. The mixture is added all the time, constantly moistening the tampon.
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, processing time - 3...5 s.
Caustic soda - 120, zinc sulfate - 40. Solution temperature - 20°C, processing time - 1.5...2.0 minutes. To obtain a solution, first dissolve sodium hydroxide in one half of the water and zinc sulfate 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 minutes.
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 the surfaces of parts is used as an anti-corrosion coating and as a preliminary process (for aluminum and its alloys) before soldering with soft solders. Below are the compositions for tinning some metals.
Tinning compounds (g/l)
For steel
Tin chloride (fused) - 1, ammonia alum - 15. Tinning is carried out in a boiling solution, the growth rate is 5...8 µm/h.
Tin chloride - 10, aluminum ammonium sulfate - 300. Tinning is carried out in a boiling solution, the growth rate is 5 µm/h.
Tin chloride - 20, Rochelle salt - 10. Solution temperature - 80°C, growth rate - 3...5 µm/h.
Tin chloride - 3...4, Rochelle salt - until saturation. Solution temperature - 90...100°C, growth rate - 4...7 µm/h.
For copper and its alloys
Tin chloride - 1, potassium tartrate - 10. Tinning is carried out in a boiling solution, the growth rate is 10 µm/h.
Tin chloride - 20, sodium lactic acid - 200. Solution temperature - 20°C, growth rate - 10 µm/h.
Tin chloride - 8, thiourea - 40...45, sulfuric acid - 30...40. The solution temperature is 20°C, the growth rate is 15 µm/h.
Tin 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.
Tin 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 hangers. Small parts are “powdered” with zinc filings.
For aluminum and its alloys
Tinning of aluminum and its alloys is preceded by some additional processes. First, parts degreased with acetone or gasoline B-70 are treated for 5 minutes at a temperature of 70 ° C with the following composition (g/l): sodium carbonate - 56, sodium phosphate - 56. Then the parts are immersed for 30 s in a 50% solution of nitric acid. acid, rinse thoroughly under running water and immediately place in one of the solutions (for tinning) given 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, caustic soda - 1.5..L.7, ammonium oxalate - 10...20. Solution temperature - 20...40°C, growth rate - 5 µm/h.
Removing metal coatings
Typically, this process is necessary to remove low-quality metal films or to clean any metal product being restored.
All of the solutions below 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 sulfate (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.
To remove 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. The solution temperature is 20...80°C.
To remove nickel from aluminum and its alloys, commercial nitric acid is used. Acid temperature - 50°C.
To remove 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 (with zincate treatment)
Chromic anhydride - 480, sulfuric acid - 40. Solution temperature - 20...70°C.
Technical nitric acid. The solution temperature is 50°C.
To remove silver from steel
Nitric acid - 50, sulfuric acid - 850. Temperature - 80°C.
Technical nitric acid. Temperature - 20°C.
Silver is removed from copper and its alloys using technical nitric acid. Temperature - 20°C.
Chrome is removed from steel with a solution of caustic soda (200 g/l). The solution temperature is 20 C.
Chromium is removed from copper and its alloys with 10% hydrochloric acid. The solution temperature is 20°C.
Zinc is removed from steel with 10% hydrochloric acid - 200 g/l. The solution temperature 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 solution temperature is 20°C.
Tin is removed from steel with a solution containing sodium hydroxide - 120, nitrobenzoic acid - 30. Solution temperature - 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. solution temperature - 20°C.
Chemical oxidation and coloring of metals
Chemical oxidation and painting 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 (blackening silver, painting gold, etc.), burnishing steel objects (heating a steel part to 220...325°C, they lubricated it with hemp oil).
Compositions of solutions for oxidizing and painting steel (g/l)
Note that before oxidation, the part is ground or polished, degreased and pickled.
Black color
Caustic soda - 750, sodium nitrate - 175. Solution temperature - 135°C, processing time - 90 minutes. The film is dense and 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 minutes. The film is matte.
Caustic soda - 750, sodium nitrate - 225, sodium nitrate - 60. Solution temperature - 140°C, treatment time - 90 minutes. The film is shiny.
Calcium nitrate - 30, orthophosphoric acid - 1, manganese peroxide - 1. Solution temperature - 100°C, processing time - 45 minutes. The film is matte.
All of the above methods are characterized by a high operating temperature of the solutions, which, of course, does not allow processing large-sized parts. However, there is one “low-temperature solution” suitable for this purpose (g/l): sodium thiosulfate - 80, ammonium chloride - 60, orthophosphoric acid - 7, nitric acid - 3. Solution temperature - 20 ° C, processing time - 60 min . The film is black, matte.
After oxidizing (blackening) the steel parts, they are treated for 15 minutes in a solution of potassium chromium (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 hydrosulfide - 120, lead acetate - 30. Solution temperature - 90...100°C, processing time - 20...30 minutes.
Blue color
Lead acetate - 15...20, sodium thiosulfate - 60, acetic acid (glacial) - 15...30. The solution temperature is 80°C. Processing time depends on the color intensity.
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, treatment time - 2 hours.
Caustic soda - 550, sodium nitrate - 150...200. Solution temperature - 135...140°C, processing time - 15...40 minutes.
Caustic soda - 700...800, sodium nitrate - 200...250, sodium nitrate -50...70. Solution temperature - 140...150°C, processing time - 15...60 minutes.
Caustic soda - 50...60, potassium persulfate - 14...16. Solution temperature - 60...65 C, processing time - 5...8 minutes.
Potassium sulfide - 150. Solution temperature - 30°C, processing time - 5...7 minutes.
In addition to the above, a solution of the so-called sulfur liver is used. Sulfur liver is obtained by fusing 1 part (by weight) of sulfur with 2 parts of potassium carbonate (potash) in an iron can for 10...15 minutes (with stirring). The latter can be replaced with the same amount of sodium carbonate or sodium hydroxide.
The glassy mass of liver sulfur is poured onto an iron sheet, cooled and crushed to powder. Store sulfur liver in an airtight container.
A solution of liver sulfur is prepared in an enamel container at the rate of 30...150 g/l, the temperature of the solution is 25...100°C, the processing time is determined visually.
In addition to copper, a solution of sulfur liver can blacken silver well and satisfactorily blacken steel.
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 sulfate - 20, copper sulfate - 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 minutes.
Blue
Sodium thiosulfate - 160, lead acetate - 40. Solution temperature - 40...100°C, processing time - up to 10 minutes.
Compositions for oxidizing and painting 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°C, processing time - up to 30 minutes.
Brown color
Potassium chloride - 45, nickel sulfate - 20, copper sulfate - 105. Solution temperature - 90...100 ° C, processing time - up to 10 minutes.
Copper sulfate - 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 sulfate - 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, treatment time - 7 minutes.
3green color
Nickel ammonium sulfate - 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, treatment time - up to 60 minutes.
Compositions for oxidizing and painting bronze (g/l)
Green color
Ammonium chloride - 30, 5% acetic acid - 15, copper acetic acid - 5. Solution temperature - 25...40°C. Hereinafter, the intensity of bronze color 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
Copper nitrate - 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. Solution temperature - 18...25°C.
Patination (giving the appearance of old bronze) is carried out in the following solution: liver sulfur - 25, ammonia (25% solution) - 10. Solution temperature - 18...25°C.
Compositions for oxidizing and coloring silver (g/l)
Black color
Sulfur liver - 20...80. Solution temperature - 60..70°C. Here and below, the color intensity is determined visually.
Ammonium carbonate - 10, potassium sulfide - 25. Solution temperature - 40...60°C.
Potassium sulfate - 10. Solution temperature - 60°C.
Copper sulfate - 2, ammonium nitrate - 1, ammonia (5% solution) - 2, acetic acid (essence) - 10. Solution temperature - 25...40°C. The content of components in this solution is given in parts (by weight).
Brown color
Ammonium sulfate solution - 20 g/l. The solution temperature is 60...80°C.
Copper sulfate - 10, ammonia (5% solution) - 5, acetic acid - 100. Solution temperature - 30...60°C. The content of components in the solution is in parts (by weight).
Copper sulfate - 100, 5% acetic acid - 100, ammonium chloride - 5. Solution temperature - 40...60°C. The content of components in the solution is in parts (by weight).
Copper sulfate - 20, potassium nitrate - 10, ammonium chloride - 20, 5% acetic acid - 100. Solution temperature - 25...40°C. The content of components in the solution is in parts (by weight).
Blue
Liver sulfur - 1.5, ammonium carbonate - 10. Solution temperature - 60°C.
Liver sulfur - 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 solution temperature is 20°C.
Attention! When dyeing silver green, you must work in the dark!
Composition for oxidizing and painting 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°C, processing time - 2...10 minutes.
Grey colour
Arsenic trioxide - 70...75, sodium carbonate - 70...75. The solution temperature is boiling, the processing time is 1...2 minutes.
Green color
Orthophosphoric acid - 40...50, acidic potassium fluoride - 3...5, chromic anhydride - 5...7. Solution temperature - 20...40 C, processing time - 5...7 minutes.
Orange color
Chromic anhydride - 3...5, sodium fluorosilicate - 3...5. Solution temperature - 20...40°C, processing time - 8...10 minutes.
Yellow-brown color
Sodium carbonate - 40...50, sodium chloride - 10...15, caustic soda - 2...2.5. Solution temperature - 80...100°C, processing time - 3...20 minutes.
Protective compounds
Often a craftsman needs to process (paint, coat 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 coated is painted over with a protective composition that prevents the formation of one or another 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). This composition is prepared as follows. The wax is melted in a water bath and warm turpentine is added to it. In order for the protective composition to be contrasting (its presence could be clearly seen and controlled), the composition is a small amount of dark alcohol-soluble paint. If this is not available, it is not difficult to add a small amount of dark shoe cream to the composition.
You can give a more complex recipe, % (by weight): paraffin - 70, beeswax - 10, rosin - 10, pitch varnish (kuzbasslak) - 10. All ingredients are mixed, melted over low heat and mixed thoroughly.
Waxy protective compounds are applied hot with a brush or swab. All of them are designed for operating temperatures no higher than 70°C.
Protective compounds based on asphalt, bitumen and pitch varnishes have somewhat better heat resistance (operating temperature up to 85°C). They are usually liquefied 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 can 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 glue 88N (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) B-70 gasoline and 1 part ethyl acetate (or butyl acetate). The operating 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°C.
This is fineI agree, but there is still formaldehyde in there.
The operating principle of any shine-forming additive is micro-leveling. That is, at the microcrystalline level, the coating is deposited in the depressions faster than on the protrusions, which actually corresponds to your photo. Another aspect is macro alignment. This is an alignment in dimensions that are an order of magnitude larger than the dimensions of interatomic distances. Macro leveling is not always accompanied by shine. For example, copper cyanide levels well, but the shine is not strong.Perhaps I misunderstand the terms; I called this additive a leveler for the reason that its action in the electrolyte makes it possible to increase the class of surface cleanliness. If we compare it with galvanizing electrolytes, then there are brightening agents, but I have never heard of levelers for zinc.
This is fine. The wetting agent is adsorbed on coal better than all other additives. I have seen many cases where, after a light treatment with charcoal, there was no need to adjust the brighteners, but there was not enough wetting agent. The veil formed due to a lack of wetting agent differs in appearance and nature of formation from the defect according to your photo.From the very beginning of working with this brightener system, after cleaning with activated carbon, the wetting agent content decreases slightly and a small veil is visible on the Hull cell at medium current densities. Adding 100-150 ml of wetting agent per 1000 l (initial filling 2 ml/l) removes the veil.
All these cunning devices (-gaphs, -meters) are all good when we are dealing with a pure electrolyte that works strictly according to regulations. Another thing is when the electrolyte is dirty and/or treated with peroxide. In general, the easiest and most direct way to spoil the electrolyte is to treat it with peroxide. Peroxide does not completely oxidize all organic matter. Some organic matter is partially oxidized, then partially reduced at the anode. And these processes continue cyclically, giving more and more new organic derivatives. Therefore, no one knows how many organic compounds actually appear in such a bath and what their effect on the main organic components is, and there is no point in trying to calculate.I think they determine additives using liquid chromatography, at least in the Atotech technical instructions for one of their galvanizing processes, it is HPLC that is recommended for determining the content of additives (however, given the level of equipment of most domestic galvanizers, this is more like a malicious mockery).
That is, you determined the amount of basic organic matter using a graph. What's next? How to quantitatively take into account the influence of by-product organic matter? Therefore, no matter how cunning the device is, the most reliable method is the poke method using a Hull cell and/or a curved cathode. Nickel peroxide is a “hook” that is difficult to get off. Because if peroxide is poured once, then the products of partial oxidation/reduction will constantly accumulate and transform (quickly or slowly, but constantly). As a result, peroxide will have to be added at regular intervals. It’s good if you yourself are to blame for using peroxide (don’t follow the degreaser, rinsing, don’t wash the bags, etc.). But, if you do everything correctly, and adding peroxide is included in the regulations, then it’s the same as buying a new car, into the engine of which, according to the instructions, you need to add 1 liter of oil per 500 km.
yes, you can do it right in the bathOnce a week we rarely change anything except the rinsing baths. You may have to change it once a month, maybe once every six months. There is little hexavalent chromium there. You can manually reduce hexavalent chromium bisulfite and then pour it into the main drains.I agree, but if you dump it into the treatment plant once a week, then you need to dilute it every 50 times, otherwise the electrocoagulator will not clean enough. Please tell me how often, on average, do your clients change this activation bath?
Do you make coatings for European car brands? As far as I know, if a German workshop covers, for example, a BMW conveyor, then on Friday evening all the surface preparation and washing baths are drained. All before the galvanic baths. Fines for downtime and defective work on the conveyor are very high.Unfortunately, we are also not as close to civilization as we would like. We are trying to convince people to change chemical degreasing every six months, but cyanide electrical degreasing saves us.
Yes, but in our practice, the bathtub is changed no more than once a month (usually less often). Or rather, they change it when problems arise.Regarding the NFDS, if you don’t change it once a week or at most every two weeks, there’s no point in taking a bath. There are such small concentrations that everything will go away with the parts by the end of the week and you will get dirty water.
I don't think so either. But our bathtub is being adjusted. They correct it because they don’t change it as often as Efim’s.Honestly, I don’t know what to answer, because no one has ever corrected it. Its working concentration is only 2.6 g/l. I don't think anything is accumulating there, try it if there is a problem with the amount of wastewater.
Thank you for your answer, I have never seen such a radical approach to processing with peroxide - thank you again for that. As for the wetting agent - yes, the problem is not in it, I remember I wrote - when removing chrome there are no stains on nickel. And yes, if the wetting agent is under-corrected, the boundaries of the spots are blurred, but here they are literally “etched out”.
Return to main article
chem21.info
If the topic is in the wrong section, please move it to the correct one, because I didn’t find a suitable one.
Gentlemen, members of the forum, tell me who knows. I'm going to take the Flaubert 4mm Cuno Melcher Magnum revolver. There is a choice: Chrome, Nickel, Blued. Since searching on the Internet did not give any results, I decided to turn to knowledgeable people: which one is better to take??? What are the pros and cons, which is more durable and corrosion resistant???
P.S.: The difference in price is not scary, only the quality is of interest.
Groz 02-05-2011 15:16
This is not for wearing, my IMHO is blued. The front cut of the drum will not be so painful to clean. But for wearing, stainless steel is better.
Idalgo 02-05-2011 17:26
I'm for stainless steel.
Foxbat 03-05-2011 12:53
Nickel is nice, but it is still a coating, and a soft one. In addition, it does not protect against corrosion by itself; it is porous. If it is not made exactly as it should, it will rust, which is very noticeable in the mass of cheap edged weapons of the late 19th and early 20th centuries, when they were popular with them. Black spots of corrosion appear on it, especially if it is damaged.
No matter what you say, you can’t imagine anything better than stainless steel!
By the way, chrome is a very rare coating for weapons; I’ve never seen it on a mass-produced one (I’m not saying it doesn’t happen, I just haven’t seen it), only on expensive sports weapons.
vovikas 05/03/2011 14:34quote: By the way, chrome is a very rare coating for weapons, I’ve never seen it on a mass-produced one (I’m not saying it doesn’t happen, I just haven’t seen it), only on an expensive sports weapon! I have my ugly Tanfogle 1911 in chrome (corrected - it was written in nickel). matte. But. It would be better if it was in "no way". scratched coating after a police check - oh well. accidentally put “not like that” - again scratches. so my conclusion is only black or stainless steel, but this is not affordable for everyone (I’m talking about stainless steel, kneshna)...filin 05/03/2011 15:36quote:chrome is a very rare coating for weapons Here we are again “ahead of the rest” "... A huge amount was covered with chrome anyhow. Coating with black chrome is quite common. Nowadays, both expensive and mid-priced hunting weapons are coated with black chrome. As for pistols - Izhmekh quite often sins with white chrome. It looks tacky. And what if on a chrome-plated PM, put a “golden” fuse, trigger, hammer and bolt stop (coated with titanium nitride) - it turns out to be a gypsy’s dream...vovikas 05/03/2011 15:42quote: it turns out to be a gypsy’s dream... but “for the gypsies” nada!!! I serve a gypsy camp (according to the sub-technical department, don’t think anything wrong). and their baron goes to shoot at our shooting range. quite an adequate guy. and looks sideways with the right eye at my 92nd Beretta, black, no frills! filin 05/03/2011 18:29quote: and looks sideways with the right eye Wrong gypsy. Maybe he doesn’t steal horses either... We have their village nearby, so almost all sets of “golden” parts for the PM went there. People's Commissar 05/03/2011 19:25
Today I clarified: there is nickel, blued. There are no chrome versions of this model, so the choice is narrowed down: Blued or nickel plated?
vovikas 03-05-2011 19:37
2ts don't bother. In any case, this is not steel, but silumin, and therefore everything else is just coloring.
quas 05/03/2011 20:16quote:Originally posted by filin:so almost all sets of “golden” parts for the PM went there. Very practical coating, durable. :-)zav.hoz 04-05-2011 16:58
If you choose from nickel-plated and blued silumin, then definitely take nickel. The “blueing” peels off once or twice. But chrome – that would be much more serious. My 1911 frame (steel) has a matte Hard-Chrome coating - it looks good, does not scratch and hardly gets dirty.
filin 04-05-2011 18:00quote: But chrome - that would be much more serious. It depends on who is doing it. I have repeatedly seen peeling chrome, but the RPK-74 barrels with a thick chrome coating lasted 30 thousand rounds with 7N6 bullets - the same ones , which M.T. Kalashnikov called “punchons.” Marxist 05/04/2011 21:54
Chrome plating is porous by nature, and porosity strongly depends on the conditions (the faster it is coated, the worse it is, if sclerosis does not fail). Porosity is not important, for example, in hydraulic equipment (everything is covered in oil anyway), but it is critical in weapons, where all sorts of aggressive nastiness accumulates in micro-machines. Moreover, it rusts under the chrome, it’s not visible at first, and when it comes out, it’s too late to drink Borzhom. Therefore, expensive weapons (barrels, in any case) are usually not chrome-plated, but are either made entirely of stainless steel or traditional materials. And nickel plating must be distinguished between electrochemical (plating, like chrome) and chemical - smoother (there is no increase in current density on micro-irregularities and no build-up of coating material on them), possibly non-porous (I won’t say so), and can be done at home.
People's Commissar 05/05/2011 22:08quote: If you choose from nickel-plated and “blued” silumin, then definitely take nickel. The “blueing” peels off once or twice. But chrome – that would be much more serious. My 1911 frame (steel) has a matte Hard-Chrome coating - it looks good, does not scratch and hardly gets dirty.
No, not silumin (except for the drum).
vovikas 05-05-2011 22:37quote: No, not silumin oh-oh!!! ok, lumin!!! Idalgo 05-05-2011 23:03
You need to take stainless steel. Ideal for a revolver.
vovikas 05-05-2011 23:13
Yes, there is no nerve in this version! Kuno doesn't do anything similar. alpha does. but only in serious calibers. so take black and touch up as it wears.
Idalgo 05-05-2011 23:24quote:Originally posted by vovikas:yes, there is no stainless steel in this version! Then of course..blue. Spraying nah.vovikas 05/05/2011 23:27quote: Then of course...it’s blued, it’s not blued. paint or something else is applied to the alloy. This is not steel!map 05/05/2011 23:33
I'm for a slingshot... with blued steel balls...
It’s not for nothing that slingshots were banned in Germany, but Flauberts were left...
zav.hoz 05-05-2011 23:49quote:Originally posted by map:It’s not for nothing that slingshots were banned in Germany. When was it banned? I seemed to see them at masses, although I was not at all interested.
As for aluminum - the coating is most likely oxidation, it is with different colors do. It can’t be washed off by hand, but a screwdriver or a rusty nail will do it once or twice!
Idalgo 05-05-2011 23:55
Well, why the hell is such happiness, even if you don’t bury the gun blue. Whatever you want, I wouldn’t take it.
gotmog 06-05-2011 10:53
If the alloy is aluminum, then the black coating is most likely obtained by anodizing. There, depending on the composition of the electrolyte, you can obtain the desired color; moreover, the oxide film obtained by anodizing is easily colored even with aniline dyes. May fade in places over time. Oxidized aluminum, as a rule, has a gray-green color. Chemical nickel plating is very durable, but thinner than electrolytic plating. But covering something with black chrome is a hell of a job - it’s too capricious a process. Among other things, the coating on aluminum alloys can be applied by gas plasma spraying and here the composition of the coating is limited only by the imagination of the “sprayers”
Idalgo 06-05-2011 12:03quote:Originally posted by DIDI:He just didn’t see the “correct gypsy” Beretta. Damn it..give me two!!!Paul! Can I send you yours for engraving? I want it, like a gypsy baron!!! People's Commissar 06-05-2011 13:09
so, I take the black one (either blued or some other crap). Thanks everyone for the information.
Dear admins, do not close the topic yet, because there are no similar topics on the Hansa, and if anyone needs anything, let them discuss it here, thank you in advance.
map 06-05-2011 19:59
[B]When was it banned? I seemed to see them at masses, although I was not at all interested.__________________________________________________________________________
Two or three weeks ago there was information on TV: a Lufthansa pilot was sentenced to 1.5 years for importing two slingshots and ammunition for them with steel balls into Germany...
4erepaha 07-05-2011 16:05
Two or three weeks ago there was information on TV: a Lufthansa pilot was sentenced to 1.5 years for importing two slingshots and ammunition for them with steel balls into Germany...)
