6063铝合金无铬有色化学转化工艺探讨  

Investigation of Chromium-Free Colored Chemical Conversion Technology for 6063 Aluminum Alloy

作　　者：刘晓辉[1] 欧阳贵[1] 占稳[1] 

机构地区：[1]武汉材料保护研究所,湖北武汉430030

出　　处：《材料保护》2014年第3期28-30,36,共4页Materials Protection

基　　金：湖北省自然科学基金(2013CFB483)资助

摘　　要：为了进一步提高6063铝合金表面无铬转化膜的性能以替代铬酸盐钝化膜，以钛盐为成膜主剂，钨酸盐为上色剂，多羟基有机酸钠为配位剂，在6063铝材表面进行无铬有色化学转化，采用铬酸盐点滴试验、电化学方法、中性盐雾试验及划格法对转化膜的耐蚀性、附着力进行了测试，并对转化液配方及成膜条件进行了优选，探讨了添加剂及工艺参数对膜层质量的影响。结果表明：较优转化液配方及成膜条件为2．0g／L钛盐、0．3-0．5g／L钨酸盐上色剂，0．5～0．7g／L多羟基有机酸钠配位剂，25～30℃，pH值为3．2～3．6，转化时间为5～7min；优化工艺可在6063铝合金表面获得均一的金黄色无铬转化膜，自腐蚀电流密度仅为基材的1／6；转化膜与聚酯漆膜的附着力与六价铬转化膜的相当；该工艺完全无铬、无毒。A chromium-free( without trivalent chromium) colored chemical conversion technology for6063 Al alloy was established with titanium salt as the main filmforming agent,tungstate as the colorant,and sodium multi-hydroxyl organic acids as the complexing agent so as to replace chromate passivation and improve the performance of the Cr-free conversion coating on Al alloy surface. The corrosion resistance and adhesion force of as-prepared conversion coating were determined by chromate dripping test,electrochemical method,neutral salt spray test,and grid test. Moreover,the effects of additives and processing conditions on the quality of the conversion coating were investigated,and the composition of the conversion fluid and film-formation condition were optimized. Results indicated that the conversion solution had an optimal composition of 2. 0 g /L titanium salt,0. 3 ~ 0. 5 g /L tungstate colorant,and 0. 5 ~ 0. 7g /L sodium multi-hydroxyl organic acid complexing agent,and the optimal processing parameters were suggested as a temperature of 25 ~ 30 ℃,a pH value of 3. 2 ~ 3. 6,and conversion time of 5 ~ 7 min. A uniform Cr-free golden-yellow conversion coating could be obtained on the surface of Al alloy under the optimized processing condition,and the corrosion current density of as-prepared conversion coating was only 1 /6 of that of the substrate.Moreover, the adhesion force of the conversion coating to polyester tarnish coating was comparable to that of hexavalent Cr conversion coating.

关 键 词：化学转化 无铬有色转化膜 6063铝合金 耐蚀性能 附着力 

分 类 号：TG174.4[金属学及工艺—金属表面处理]