2013•Cailiao daobaoRequires access
Study on Additives in Phytic Acid Treatment for Diecasting Magnesium Alloy
Song Dong-f
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Abstract
Two different kinds of phytic acid conversion coatings on magnesium alloy were prepared in phytic acid base conversion solution with accelerants.The effect of additives on the structure,morphology and corrosion resistance of conversion coating were investigated by SEM,EDS and weight loss method,respectively.The results show that the magnesium alloy surface corrosion performance is improved substantially through phytic acid conversion treatment,and the weight loss of conversion coating is only 1/5of the magnesium alloy substrate after 120hsaline soaking.The structure and compactness of conversion coating are greatly improved by adding Ca(NO3)2,NH4VO3and Na2C4H4O6·2H2O,as the conversion coating consists of inner layer which is combined with the substrate compactly and outer layer which exhibits overlapping curve.The corrosion resistance of corversion coating increases 100%compared to pure phytic acid conversion coating.However,other additives such as NaF,Na2B4O7and Na2C4H4O6·2H2O have no significant impact on structure and corrosion resistance of phytic acid conversion coating.