The influence of each acid-etching factor on the properties of zinc-immersion coating was analyzed by polarization curves,scratch and thermal shock testing,and the optimal formula of acid-etching for AZ 91D magnesium alloy was determined.

The types of hot-dip galvanized coatings and the effects of alloy elements on the structure and performance of hot-dip galvanized coatings are introduced.

Oxide can be removed effectively after activation in the solution of H_3PO_4+NH_4HF,while adhesion ability of latter zinc immersion coating to substrate can be enhanced.

Zinc-immersed coatings were prepared on AZ91D magnesium alloy substrates using zinc immersion processes of zinc alone,binary Zn-Fe,Zn-Ni,Zn-Co,and Zn-Cu,and ternary Zn-Ni-Fe,aiming at improving the adhesion to substrate and cor-rosion resistance of follow-up electroless or electroplated coat-ings.

In order to substitute the cyanide complexing agent in the zincation solution,based on a lot of study on different complexing agent combinations,4 better cyanide-free zincation solutions are selected to compare with commercial cyanide-contained zincation solution for their performances,including micromorphology,components of the zinc deposit and the surface morphology and cor.

The quality of nickel deposit is an important indicator to test the performance of cyanide-free zincating solution for high-Si aluminum alloy.

Pre-treatment of aluminium surface for Ni-Fe plating including solutions for alkaline etching, pickling, zincating, activating and properties of the deposit obtained on 6063.