How to control the stability of chromium plating solution for tin cobalt alloys

Sufficient tin salt complexing agent such as potassium pyrophosphate and some reducing substances are added to prevent divalent washing and oxidation to tetravalent tin! In order to prevent the oxidation of divalent tin by the oxygen produced by the anode, you can refer to the practice of trivalent chromium plating, such as using a special anode!

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Since there are two types of chrome plating, decorative chrome plating and functional (mainly hard chrome) plating, therefore, there are two corresponding types of chromium substitution processes, one is the appearance of similar to decorative chromium chrome coating, such as high tin copper alloy, tin, cobalt-nickel alloy, etc.

The other is to use wear-resistant alloys or composite coatings, such as nickel-tungsten alloys, and use electroless plating or electroplating methods to add nanoparticles (diamond, silicon phosphide, silicon nitride, etc.) to the plating solution to obtain a composite coating with good wear resistance.

Hot-dip galvanizing, also known as hot-dip galvanizing, is a method of degreasing and removing rust from steel workpieces to present a stain-free and infiltrated surface, and immediately immerse them in the plating tank where the zinc has been heated and melted in advance, forming a layer of zinc coating on the surface of the workpiece. Cold galvanization is to hang the workpiece that has also undergone degreasing and rust removal to show no dirt and infiltration into the cathode in a special electroplating tank, and zinc is used for the anode. When the DC power supply is turned on, the zinc ions on the anode migrate to the cathode, and the discharge is discharged on the cathode, so that the workpiece is coated with a layer of zinc layer.

The hot-dip galvanized coating is thicker, generally 30-60 microns, and the coating has a high anti-corrosion ability. Long-term rust prevention of steel parts suitable for outdoor work, such as highway fences, power towers, large-size fasteners and other relatively "coarse" workpieces. Older iron water pipes were also hot-dip galvanized.

Electrogalvanized, the surface of the workpiece is smooth and flat, but because the coating is relatively thin, generally within 5-30 microns, the anti-corrosion time will be relatively short. They are used for rust prevention of indoor parts, such as chassis bottoms, panels, small-size fasteners, etc.

Chromium substitution electroplating process, the color and corrosion resistance of the plating layer can be comparable to chromium, the energy consumption is lower than chrome plating, and the deep plating ability of the plating solution is far better than that of chrome plating, which is used for the conventional barrel plating production of small parts and the hanging plating of large workpieces. The economic benefits are significant.

Chromium substitute plating additives are divided into cylinder opening agent, additive A, additive B and stabilizer.

1. Formula and operating conditions: 320 ml of chromium opener, 90 ml of chromium additive, 60 ml of chromium stabilizer, and chromium additive B

10 ml liters (need a brighter blue coating before adding).

pH (can be adjusted with phosphoric acid or sodium hydroxide) 10 11 temperature 40 50 degrees Celsius anode 1 chromium 18 nickel 9 titanium stainless steel.

Current density hanging plating.

Barrel plating 60 100a barrel cathode movement 25 30 times drum rotation speed 4 6 rpm.

2. Preparation of electroplating solution.

1. Add 30% water to the plating tank with the specified volume;

2. Add the required amount of stabilizer and stir well;

3. Add chromium substitute additive A, stir evenly, and slowly add chromium substitute cylinder opener while stirring (if necessary, add additive B last).

4. Check the pH value of the above solution and control the pH value to be about 10;

5. Add water to the specified volume and heat to about 45 degrees, then the plating can be tested;

3. Supplement of chromium substitution electroplating supply solution:

After normal production (generally the next day after the slotting), additive A, cylinder opening agent and stabilizer are supplemented according to the consumption of kiloampere-hours; If you need to add blue and bright coating, add additive B at the same time. Cylinder opener: additive a = 3:1

Chromium substitute additives in kiloampere-hours.

Chromium replacement cylinder opener liters kiloampere.

Chromium stabilizer liter kiloampere.

Chromium substitute additive B

liters of kiloampere-hours (replenished when plating more blue and bright coating).

4. Example: Prepare 100 liters of chromium electroplating solution.

1. Pour 30 liters into the plating tank.

2. Add 5 liters of chromium stabilizer and stir well.

3. Add 9 liters of chromium substitute additive A, stir evenly, and slowly add 32 liters of chromium substitute cylinder opener under continuous stirring.

4. If the color of the coating is bluer and brighter, additive B1 liter can be added.

5. Use phosphoric acid (about 200 ml, diluted with 1 liter of water) to adjust the pH value of the above solution to 12

6. Add water to 100 liters and heat to about 45 degrees, and then you can test plating.

Fifth, the process flow (example).

Plated parts with a good bottom layer (including acidic bright copper, bright nickel, nickel-iron, copper-tin alloy or zinc-copper alloy, etc.) Washed Weak acid activation Washed chromium plating Washed Passivated Washed Washed Dried Inspection Finished product.

The landlord can go to the plating manual, which is clearer.

First of all, there are a lot of plating manuals. Secondly, your question is very levelless. The plating process is formulated for the substrate.

Aluminum alloy is also silver-plated as stainless steel, but the process is different, understand? Contact me if you need a plating manual. The third edition of the latest electroplating manual, published by the National Defense Industry Press, is very practical and comprehensive.

Leave an email and I'll send it to you.

Copper-tin alloy plating can be divided into low tin (tin content 2% 15%) plating, medium tin (tin content 15% 40%) plating and high tin (tin content 40% 50%) plating according to the tin content. According to the different tin content, the plating presents different colors, red, golden yellow, light yellow, silver white, etc. The low tin coating has few pores and good primitivity, but the stability of the color is poor, and it is easy to be oxidized and discolored in the air.

Therefore, it is generally only used as the bottom layer of the plating. The appearance of the tin bronze coating is silvery-white, which is not easy to lose luster in the air, can resist weak acids and alkalis, has good brazing and conductivity, and is commonly used as silver, chromium and nickel plating. The medium tin bronze coating is between the low tin and high tin bronze plating, and the practical application is less.

Chromium substitution plating process, the color and corrosion resistance of the plating layer can be comparable to chromium, the energy consumption is lower than chrome plating, and the deep plating ability of the plating solution is much better than that of chrome plating, which is used for the conventional barrel plating production of small parts, and the economic benefits are significant.

The chromium substitution process uses tin-cobalt-zinc alloy electroplating as chromium substitution plating, which has been widely used in Guangdong in recent years. Chromium substitution plating process, the color and corrosion resistance of the plating layer can be comparable to chromium, the energy consumption is lower than chrome plating, and the deep plating ability of the plating solution is much better than that of chrome plating, which is used for the conventional barrel plating production of small parts, and the economic benefits are significant.

The process flow of chromium substitution electroplating process is usually as follows: the plated parts that have been plated at the bottom layer (including acid bright copper, bright nickel, nickel-iron, copper-tin alloy or zinc-copper alloy, etc.) Washing Weak acid activation Washing Chromium substitution electroplating Washing Passivation Washing Drying Inspection Finished product. Typical process recipes and operating conditions:

Chromium Replacement Cylinder Opener 320 ml Chromium Replacement No. 1 90 ml Chromium Stabilizer 50 mL Liter Chromium Replacement No. 3 10 ml Liters pH value (can be adjusted with phosphoric acid or sodium hydroxide) Temperature 40 50 Anode 1Cr18Ni9 Ti A small amount of pure zinc plate (about 1 5 total anode area) Current density A dm2 during rack plating 60 100 A barrel cathode movement 25 30 times Split drum rotation speed 4 6 rpm Fractional chromium plating solution contains a variety of metal salts, complexing agents, buffers and brighteners. The pH value of each variety in the range of chromium substitute additives is different, for example:

Chromium substitute supply No. 1 PH value 12 13, chromium substitute replenishment No. 2 pH value 2 3, chromium replacement cylinder opener pH value 7 8, chromium stabilizer pH value 8 9, so a variety of metal salts, a variety of complexing agents, etc., different pH solutions are mixed together, it is very easy to cause turbidity and precipitation of the plating solution. Attention must be paid to the feeding sequence when formulating. It is normal for the plating solution to be slightly turbid during the production process, and it has little effect on the brightness of the plating solution.

However, when there is severe turbidity, the plating solution becomes milky white, and the plating is easy to turn gray-white or dark, and even if other supplements are added, it is difficult to plating the blue-white and bright chromium coating. It must be dealt with in a timely manner. The cause of turbidity is mainly the hydrolysis of tin salts or the formation of cobalt hydroxide precipitates.

When the stabilizer content is insufficient or the concentration of metal ions is too high, or the pH value is improper and the temperature is too high, the turbidity of the plating solution will be accelerated.

Chromium substitution plating is a kind of electroplating of tin, cobalt-zinc ternary alloy with a surface color very similar to the chrome plating layer. It is generally used for barrel plating of small parts and surface decoration.

chromium substitution plating; Tin, cobalt, zinc (alloy plating). The color and corrosion resistance of the coating are slightly inferior to that of chromium.

Our company specializes in the production of chromium substitution plating additives.

Chromium replacement cylinder opener 320 ml.

Chromium substitute no. 1 90 ml liters.

Chromium stabilizer 50 ml.

Chromium substitute No. 3 10 ml liters (needs to be bluer.

pH (can be adjusted with phosphoric acid or sodium hydroxide) 10 11 temperature 40 50

Anode stainless steel plate.

Current density A dm2 in the case of hanging plating

60 100 A barrels for barrel plating.

Cathode movement 25 30 times.

Drum speed 4 6 rpm.

Chromium coating nickel cobalt iron and cobalt phosphorus x coating are two chromium coatings, of which chromium coating nickel cobalt iron is the ideal coating at present, cheap, pollution-free, but containing nickel, socks will cause itching, so cobalt phosphorus x coating is the final chromium coating.

Yantai Electroplating Technology Research Institute is committed to the research of cobalt phosphorus X coating, and applies it to the piston rod instead of chromium and the hydraulic oil lever instead of chromium.

It can be equipped with industrialized chrome plating (

co-p-x

Amorphous coating).

The table below provides some non-chrome substitution for hard chrome and decorative chrome plating methods.

Many generations of chromium technology are built on nickel.

on the basis of. Nickel salts too.

items listed for voluntary reductions.

A kind of dangerous chemical swim is good to destroy one.

Cause a commotion.

In all areas of application, there is only one coating due to its combined properties.

co-p-x

Amorphous deposition replaces hexavalent chromium coatings in all applications.

should be the most important according to each application.

The nature of the selection of the replacement of the coating. The trade name and manufacturer of the solution are included in the table below.

co-p-x

Amorphous deposition, hardness greater than.

Heat treatment is greater than.

1000, the plating conditions are controllable, and the chromium substitution technology is built on.

Cobalt-based and completely non-toxic. It can completely replace hexavalent chromium plating.