Zinc and zinc aluminium alloy coating of steel using hot dipping technique

Zinc and Zinc Aluminum Alloy Coating of Steel Parts Using Hot Dipping Technique In this work, the effect of bath temperature and dipping time on the coating thickness, structure of the coating layer and adhesion quality were determined for pure zinc, ZnA15 and ZnA125 alloy coating of TS Fe 37 steel parts using hot dipping technique. In addition, the stress corrosion behavior in nitric acid solution of the coated and uncoated specimens were compared. As the dipping time increased, the coating thickness increased marginally, and the coating thickness showed a small decrease as the bath temperature increased for both zinc and ZnA15 alloy coatings. Howewer, as the bath temperature or dipping time was increased, the thickness of the zinc aluminum alloy coating increased. The coatings made at high bath temperatures appeared to be dull. Microcracks were observed in ZnA125 alloy coatings and coating layer was found to be seperated from the surface of the base metal when either the bath temperature or dipping time exceeded a certain level. It was also found that hot dip coating increased the stress corrosion resistance of the steel parts in nitric acid solution. In addition, the specimens which were coated with ZnA15 alloy showed higher stress corrosion resistance than the specimens coated with either pure zinc or ZnA125 alloy. Key Words: Hot Dip Coating, Coating Thickness, Coating Quality and Stress Corrosion VI