Hard chromium additives
CR-2 high efficiency hard chromium additive
Cathodic current efficiency of up to 2 . 4 to 26%, is a conventional standard chrome plating process 2-3 times, energy conservation.
2. Use the current density broad, 2 0- . 6 0A / d㎡ can, deposition speed.
3. No fluoride, no corrosion to the low current density area of the substrate, no corrosion to the anode.
4. The microhardness of the coating can reach 1000-1100KHN 100
5. The plating layer is bright, smooth and fine, uniform thickness, and good deep plating ability.
6. The plating solution is stable, easy to operate and easy to maintain.
2. Solution composition and operating conditions
Ingredients and parametersrangebest value
C r O 3220- 2 8 0g/L2 5 0g/L
H 2 SO 42. 2-2.8 g/L2.5 g/L
CR-2 hard chromium additive1 8 -2 2 ml/L2 0 ml / L
Ratio of chromic acid and sulfuric acid1 00 :( 0.8-1.2 )100:1
temperature5 0 -60 ℃55 ℃
Cathode current density2 0- 6 0A/d ㎡50 A/d ㎡
Voltage15 volts or more
Deposition rateWhen the current is 50 A/d ㎡ and the temperature is 55 ℃ , the deposition rate is about 1.0 micron / min
3.Plating solution preparation
1. Clean the plating tank, add two-thirds of the volume of water, and heat to 45 ℃.
2. Add chromic anhydride ( 250g/L ) and stir well.
3. The addition of chemically pure sulfuric acid ( 2. . 5 G / L, note that the content of chromium sulfate anhydride deducted in,) and mix.
4. Add 20 ml/L of CR-2 hard chromium additive , add water to the required volume, and stir evenly.
5. Place a lead-tin anode containing 7-10 % Sn, use a false cathode with an area five times that of the anode, and electrolyze it at D k =15A/d ㎡ for 4 hours to produce a proper amount of trivalent chromium.
6. Heat the plating solution to 55 ℃ and start electroplating.
4.Plating solution maintenance
1. Approximately 10ml of CR-2 hard chromium additive is added for every 1000 AH of electricity , or 5-7 liters of CR-2 hard chromium additive for every 100 kg of chromic anhydride added .
2.H 2 SO . 4 normal concentration of 2. . 5 G / L. Usually sulfuric acid not consumed, with the loss only.
3. It is recommended to add our product CR-53 or CR-53A chromium mist inhibitor to reduce chromium mist escape and avoid air pollution and loss of chemical raw materials.