摘要：

Due to the plentiful surface defects and the densely crystallized microstructure layer being thin on zinc based die castings, it is advised that the process for their direct low chromate passivation should comprise: (1)getting bright and clean surface without over-corrosion by means of degreasing in mixed low alkaline solution and descaling by the three-step method , (2) passivating in appropriate low chromate solution.The resulting passivation film is highly iridescent and has better corrosion resistance in industrial atmosphere than the one on zinc coating.

展开