| The application of Dacroment technology has been very mature in domestic and abroad, which was be alternatived electro-galvanizing and hot dip galvanized because of its good performance, it has been applicated in every aspect of life. But the most important disadvantage of dacroment coating is that it contains hexavalent chromium. As a result of its harm for human and environment, after the 1990s, countries in Europe had enacted relevant laws and regulations to restrictor and prohibit the use of hexavalent chromium. The development of Chrome-free zinc-aluminum coating in base of dacro technology, its has the same good performance as dacroment coating and dose not contain any form of chromium, it is the true green processing treatment on material surface. The paper describes the original and the characteristics of the dacroment coating, summarizes the development,researching status and the application of Chrome-free zinc-aluminum coating. On the base of it,I try to research and development the environmentally friendly chrome-free zinc-aluminum coating and let it has good performance.This study is from the start of adhesive passivating agent of the coating, finally I choose to mix resin liquid and coupling agent as adhesive passivating agent of the coating and test it through neutral salt spray tese. Then I get the basic recipe of chromium-free Zn-Al coating. The coating's SST time is exended through the use of new and environmentally friendly surface treatment by Silane, after the silane pretreatment the paint is coated. The recipe of paint is obtained by choosing metal, powder, preparing mixed solvent, adding additives and other components.The article discussess various infection factors and preparation technology of coating. The effect of the content of zinc flakes and aluminum flakes, adhesive passivating agent, the species of Wetting agents on the appearance, Viscosity,stability of paint and appearance, adhesion, amount and corrosion resistance of coating are analyzed. Results It gives the major components of Chrome-free zinc-aluminum coating via SST.Through to between Dacroment coating, Geomet coating which is imported and Chrome-free zinc-aluminum coating prepared by the best formula and processes, we can conclude that there are no different on basic property between coating by ourselves and other two kinds of coating, the further strengthen of corrosion resistance must be done. The morphology, structural section, binding method and corrosion are analyzed with SEM, EDS, XPS and electrochemistry test. Preliminarily discuss to the mechanism of film formation and anticorrosion.Although we acquire the basic recipe of paint and the good property of coating, we must in-depth study and pefect in order to further improve on corrosion resistance and profound understanding of the coating mechanism. |
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