铝合金表面锆盐转化膜的制备及其性能

Preparation and Performance of Zirconium Salt Conversion Film on Aluminum Alloy

为提高铝合金涂膜的结合力及耐蚀性,在铝合金表面制备了锆盐转化膜。通过盐雾试验、电化学试验、膜微观结构与涂膜结合力测试,研究了锆盐转化膜的耐蚀性与漆膜的结合力,并与通用的铬酸盐转化膜和无铬转化膜进行对比。结果表明:锆盐转化膜120h盐雾试验的耐蚀等级达8级,在3.5%NaCl溶液中铝合金的自腐蚀电位明显正移,腐蚀电流密度大大降低;转化膜层均匀多孔,含有Al,O,Zr和Mg元素,且与漆膜结合力良好。

Conversion film of zirconium salt was prepared on the surface of Al alloy so as to improve the corrosion resistance.Thecorrosion resistance of the conversion film of zirconium salt was evaluated by conducting salt-spray tests and electrochemical tests.The adhesion of the conversion film to lacquer coatings was examined,and its microstructure was observed as well.Moreo-ver,the conversion film of zirconium salt was compared with con-ventional conversion film of chromates and Cr-free conversion film as well.Results indicate that the corrosion resistance of the zirco-nium salt on Al alloy is ranked as grade 8 after 120 h of salt-spray tests.It led to obvious positive shift of corrosion poten-tial and significant decrease of corrosion current density of Al al-loy in 3.5% NaCl.In one word,the as-prepared conversion film of zirconium salt on Al alloy was uniform and porous.Composed of elements including Al,O,Zr and Mg,it had good adhesion to lacquer coatings.