Research On Trivalent Chromium Passivation And Corrosion Resistance Of Galvanized Steel Plate

Six valence chromium passivation process of traditional are usually used toimprove the corrosion resistance and amend the color appearance of the coating.As the toxicity and the carcinogenicity of six valence chromium, it has great effecton the human’s health and environment. In contrast, the trivalent chromiumpassivation process does not produce toxic, and the coating performance obtainedwas similar with six valence chromium passivation coating. So it appearsgradually instead of six valence chromium passivation technology trends. Thispaper studies the trivalent chromium passivation of zinc coating, preliminaryanalysis the corrosion resistance and other properties of the coating.Preparation of trivalent chromium passivation coating by changing the basicbath composition and technological parameters of passivation process on thesurface of galvanized steel sheet, and obtained the optimum passivation processdata based on the analysis of the results of orthogonal test. Proceed to single factortest of passivation process by result of the orthogonal test. Study the influence ofpassivation temperature, passivation time, the time of transfer, pH value and otherparameters to the corrosion resistance of passivation coating on the surface ofgalvanized steel sheet.Test the Tafel curve and diagram of impedance spectrausing method of electrochemical on passivation coating, and do the neutral saltspray test (NSS), measure the thickness of the coating. Analysis the influence oncoating performance by changing conditions of the process, and further determinesthe optimum process of trivalent chromium passivation. This process comparedwith the original process, corrosion resistance is greatly improved, the neutral saltspray test time up to192hours.Combined with the demand of the enterprises actual production, comparison ofcoating properties on the optimized process and some commercial process,corrosion resistance and other properties are greatly enhanced, and thus provides abasis for enterprises to choose what kind of process production.