NdFeB plating adopts different plating processes according to the different environments where the products are used, and the surface plating is also divided into two categories, zinc plating and nickel plating.
Plating classification
NdFeB plating adopts different plating processes according to the different environments of the products, and the surface plating is also divided into two categories, one is zinc plating, which is used for conventional products; the other is nickel plating, which is used for products with higher requirements. There are also a few products from the machine needs to start and require other plating, such as alloy plating, silver plating and so on.
Galvanized
The zinc plating of NdFeB products adopts the process of chemical dip zinc plating and then galvanizing.
①Chemical dip zinc plating
Zinc sulfate: 35g/L, potassium fluoride: l0g/L, potassium pyrophosphate: l20g/L, temperature: 90℃, sodium carbonate: l0g/L, time: 40s.
②Potassium chloride bright galvanizing
Potassium chloride: 180-200g/L, pH: 5.0-5.5, zinc chloride: 60-80g/L, temperature: room temperature, boric acid: 25-35g/L, current density: l-2A/dm2, commercial brightening agent added according to the instructions.
③ Post-plating treatment. The zinc-plated NdFeB products must be passivated, which can be passivated by low chromium or trivalent front and meta-chromium, and then the surface is coated with masking paint after drying. Color passivation of neutral salt spray test requirements of not less than 72h.
(2)Nickel plating
NdFeB nickel plating is actually a multi-layer plating, need to be pre-plated nickel, and then thickened by copper plating, and then bright nickel surface plating.
Pre-nickel plating
Nickel sulfate: 300g/L, pH: 4.O ~ 4.5, nickel chloride: 50g / L, temperature: 50 ~ 60 ℃, boric acid: 40g / L, current density: 0.5 ~ 1.5A / dm2 additives in the right amount of time 5min
②Thickening of copper by pyrophosphate plating. As an intermediate plating, although the popular use of acid bright copper plating process, but for NdFeB material, thickening plating should not be used acid copper plating, this is because in a strong acidic plating solution, has been pre-plated with cathodic plating layer of porous materials will be very easy to occur in the substrate microscopic corrosion; for the future delayed blistering to leave a hidden danger. A more suitable process is the near-neutral copper pyrophosphate plating.
Copper pyrophosphate: 70g/L, brightener: appropriate amount, potassium pyrophosphate: 300g/L, pH: 8 ~ 8.5, ammonium citrate: 30g / L, temperature: 40 ~ 50 ℃, ammonia: 3mL / L, current density: l ~ 1.5A / dm2.