Tin plating techniques cobalt-base alloys

Tin cobalt alloy coatings with elegant color, deeply, and people have been widely applied in jewellery, watches, glasses, buttons, etc. The author introduces the tin plating technology and components of cobalt alloy plating, maintenance and troubleshooting.

1 process and formula

1.1 process

Besides oil - a copper plating a nickel plating a tin cobalt alloy

1.2 solution formulation and process conditions

Metal tin 4 ~ 6g/L, cobalt metal 10 ~ 12g, L, coordination agent, 5g/L 3 ~ 200 ~ focal potassium phosphate 250g/L, 0.3 ~ 1.5 A/dm2, 40 ~ 50 ° c, pH value of 9 O ~ 1.5, 30 ~ 60s, craphite anode, adopting precision filtration, 5tzmPP for continuous filtration.

Two main composition and electroplating process parameters

2.1 cobalt metal

Cobalt metal alloy is one of main component, improve the quality of cobalt salt concentration can make coating color deepens, increase its brightness. But high cobalt affects their ability to both plating.

2.2 metal tin

Metal alloy solder is one of main component, improve the quality of tin salt concentration can reduce black and enhance their ability to both plating. But the quality of high concentration, coating color slants white.

230 focal tetrapotassium pyrophosphate

Focus primarily on Trisodium Phosphate coordination effect. With the cobalt and tin coordination in the plating stability, also can improve the conductive function.

2.4 coordination

Agent can improve the coordination ability and enhance both plating coating brightness, excessive coordination agent can make hair color and low potential in reducing all plating capability.

Excessive coordination agent can use carbon powder.

2.5 temperature

Rising temperatures could make coating color deepened, but will affect all plating capability. Temperature is not above 60 ° c, otherwise, the tin bath salt, easy hydrolysis.

2.6 pH value

To improve the pH bath makes deep plating capability and all plating capability. Low pH value, electroplating easily hydrolyzed.

3 process maintenance

(1) the salt, should complement with focal sodium hexametaphosphate coordination rear can join.

(2) increasing the quality of potassium phosphate coke, can reduce the concentration of white precipitation.

(3) increase anode area can make bivalent tin plating, benefit to slow Sodium acid pyrophosphate stability.

(4) with plastic cover good production with chamfer, tied around the best reduction in contact with the air, and oxidation becomes muddy.

(5) before electroplating process electrolysis 30min ~, If long-term use, should electrolytic processing 2 ~ 3h.

(6) will be cloudy solution for long-term use, and have accumulated, can add two organic carbon powder 4g ~ / process. After filtering, should according to the supplementary hall coordination.

(7) with strong hydrochloric acid unqualified plating nickel plating, back in again after plating.