热镀锌后镧盐转化膜的制备及耐蚀性能  

Preparation and Corrosion Resistance of Lanthanum Conversion Coating on Galvanized Steel

作　　者：孔纲[1] 刘玲艳[1] 钟正[1] 卢锦堂[1] 

机构地区：[1]华南理工大学材料科学与工程学院,广东广州510640

出　　处：《材料保护》2010年第7期36-39,共4页Materials Protection

基　　金：国际铅锌研究组织项目(ILZRO/IZA/2009023);中央高校基本科研业务费专项资金(2009ZM0072)

摘　　要：镀锌层稀土转化膜防护效果良好,且无毒、无污染。采用镧盐代替铬酸盐对热镀锌表面进行钝化,用中性盐雾试验评价膜层的耐蚀性,研究了镧盐转化膜制备中钝化液组成、温度及钝化时间等对转化膜耐蚀性的影响,并通过正交试验获得钝化处理的最佳工艺。结果表明:最佳成膜工艺为18～22g/LLa(NO3)3.6H2O,5～15mL/LH2O2,10～15g/L柠檬酸(H3Cit),温度60～80℃,时间10～30min;La(NO3).6H2O浓度对镧盐转化膜耐蚀性的影响最大,处理时间次之,之后是成膜温度,H3Cit浓度的影响最小;采用最佳工艺获得的转化膜同时抑制了锌腐蚀反应的阴极和阳极过程,膜层耐蚀性能优于常规铈盐转化膜。Lanthanum nitrate was used to replace chromate for passivation of galvanized steel. The corrosion resistance of resultant lanthanum conversion coatings was evaluated by using neutral salt-spray tests. The effects of bath composition , temperature and time on the corrosion resistance of the conversion coatings were investigated, and the optimized passivation parameters were determined based on orthogonal tests. The optimal bath composition for obtaining lanthanum nitrate conversion coatings on galvanized steel was determined as 18～22 g/L La(NO3)3 ·6H2O, 5～15 mL/L H2O2 and 10～15 g/L citric acid, while the optimal passivation parameters were determined as passivation solution temperature of 60～80 ℃ and passivation time of 10-30 min. Concentration of La(NO3 )3 ·6H2O had the most prominent effect on corrosion resistance of the lanthanum nitrate conversion coatings, followed by passivation time, passivation solution temperature, concentration of H2O2 and concentration of citric acid. The conversion coating obtained under the optimal technology inhibited both the anodic and cathodic processes of the corrosion reaction, showing much better corrosion resistance than cerium conversion coating.

关 键 词：转化膜 钝化 镀锌层 稀土 耐蚀性 

分 类 号：TG174.4[金属学及工艺—金属表面处理]