[ALUMINIUM NETWORK] The pre-treatment process for electroplating on aluminum or aluminum alloys is based on a synthesis of the literature: (1) After chemical etching or mechanical polishing, the oxide on the surface of the plating part is removed and directly plated; (2) Electroplating after zinc plating ;3 Electroplating after anodization. Currently widely used is zinc immersed and anodized two processes. Electro Galvanized Iron Wire,Galvanized Wire,Galvanized Iron Wire Puersen Hardware Wire Mesh Products Co., Ltd. , http://www.sjz-wiremesh.com
Because the aluminum alloy bush is a bimetallic layer structure, the electroplating pretreatment process must ensure the binding force of the coating, and it should also ensure that the steel back after precision machining does not cause excessive corrosion, so the pretreatment process and the purity of the aluminum alloy bearing bush plating The pretreatment process of aluminum alloy plating is quite different.
Researchers at the Department of Chemistry at Jiaying College conducted various tests to obtain pre-plating processes on the surfaces of aluminum-zinc alloy bearings. The results show that a nickel layer with good binding force can be obtained by using ammonium persulfate solution instead of the black film on the surface of the mixed acid bush, anodizing the aluminum-zinc alloy with the sulfamic acid electrolyte, and anodizing and then electroless nickel plating.
A pickling process using ammonium persulfate solution can not only remove the black film produced by alkali corrosion of Al-Zn alloy, but also greatly reduce the corrosion rate of steel back.
2 Using sulfamic acid as electrolyte to anodize aluminum-zinc alloy, with the characteristics of short film forming time and light corrosion to steel back.
3Aluminum-zinc alloy Anodized with sulfamic acid and electrolessly plated with nickel to obtain a nickel coating with good adhesion.
4 Aluminium-zinc alloy bush plating Pb-Sn-Cu ternary alloy pretreatment process flow is: degreasing → washing → alkali corrosion → washing → pickling (ammonium persulfate solution except black film) → washing → anodizing (aminosulfonyl) Acid oxidation) → washing → electroless nickel plating.