Study On Microstructure Test Technology Of Zinc Coating On Steel Surface

Display technology of zinc coating metallographic sample preparation and organization, research on the routine test and process identification of hot dip galvanized and galvanized have important practical significance for developing layer metallographic examination of zinc covered steel surface. In this paper, the steel surface of zinc on4different zinc plating covering layers of tissue specimen preparation technology and micro display technology were investigated. The results obtained are in following:First, through studying several sample mounting methods such as mechanical clamping, pressing, cold inlaid mosaic, a metallographic specimen with zinc covering layer can be prepared by successively mechanical clamping, the rough grinding, fine grinding and polishing. The specimen possesses a good edge effect in which the zinc covering layer has the same test level with steel matrix.Second, the zinc coatings prepared by different processing were etched by eleven etchants with various recipes and then their morphology were observed by metallomicroscope. It is believed that the microstructure of zinc coating as well as steel matrix can be clearly observed by using2%-4%nitric acid alcohol solution of picric acid, alcohol solution. If only the microstructure of zinc coating need to be observed, the water solution of hydrochloric acid, chromate or chromic anhydride sodium sulfate solution can be used as etchants. Etch might not be carried out for observing the tissue obtained by thermal spay coating.Third, compared the hot dip galvanized specimen with electro galvanized sample, the main difference between two methods is the existence of a width ranging from the dentate band organization (Γ1). Such organization can be observed at the layer of hot dipped galvanizing, not at electro galvanized layer.