When aluminum workpieces are produced with electroless nickel plating solution, in order to obtain better bonding force, the pre-plating treatment of workpieces is very important.So what pre-plating processes should we pay attention to in production?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product's electroless nickel plating solution Ni-809,usually, the chemical nickel plating process of aluminum workpieces requires attention to the three processes of degreasing, etching and zinc immersion:
1. Degreasing.Aluminum is an active metal and can react violently with acids and bases.Therefore, compared with steel, the alkalinity of the degreasing fluid should not be too strong, so as not to cause corrosion to the aluminum substrate.The content of sodium hydroxide in the general aluminum degreasing formula is relatively low, mainly sodium phosphate, sodium silicate and sodium carbonate.
2.Etching.Etching is to remove defects and impurities on the surface of aluminum to form a uniform aluminum surface.Acid etching has less corrosion to aluminum, can ensure the smoothness of the surface of the aluminum, and can also remove various impurities, thereby improving the adhesion of the coating.
3.Zinc immersion.Zinc immersion is to remove the oxide film on the surface of the aluminum material, and at the same time form a zinc substitution layer on the surface of the aluminum, which can protect the aluminum material from being oxidized.Generally, the zinc layer obtained by one-time zinc deposition is relatively rough and the coverage is incomplete.In order to obtain a relatively uniform zinc precipitation layer, 1:1 nitric acid should be used to remove it for secondary zinc precipitation.The secondary zinc deposition can obtain a uniform and dense zinc deposition layer.
Therefore, our aluminum workpieces need to pay attention to these three pre-plating treatment processes in the production process of electroless nickel plating solution, which can effectively improve the quality of electroless nickel plating and reduce the failure rate.