热浸镀锌–铝层表面镧盐转化工艺  

Lanthanum conversion on surface of hot-dip galvanized zinc–aluminum coating

作　　者：吴晓晓[1] 孔纲[1] 车淳山[1] 张晓根 

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 [2]黄家埠镇安监所,浙江宁波315400

出　　处：《电镀与涂饰》2015年第11期621-625,共5页Electroplating & Finishing

基　　金：国际铅锌研究组织资助项目(ILZRO/IZA/CN201212);中央高校基本科研业务费项目(2012ZM0011);广东省教育部产学研结合项目(2012B091100312)

摘　　要：分别以La（NO3）3·6H2O为主盐、H2O2为氧化剂和Na F为促进剂,对钢铁基热浸Zn–2%（质量分数）Al合金镀层进行化学转化。通过正交试验研究了不同因素对转化膜耐蚀性的影响,得到镧盐转化的最佳工艺条件为：La（NO3）3·6H2O 10~15 g/L,H2O2 10 m L/L,Na F 0.5 g/L,温度70°C,时间10~30 min。成膜温度和处理时间对转化膜耐蚀性的影响较大,Na F的加入有利于成膜。在最佳工艺条件下得到的镧盐转化膜经过3个周期中性盐雾试验后的白锈面积分数为15%,耐蚀性明显优于未钝化试样。Hot-dip galvanized Zn–2wt% Al alloy coating on steel substrate was chemically conversed in a solution with La（NO3）3＆#183;6H2O as main salt, H2O2 as oxidant, and NaF as promoter. The effects of different factors on corrosion resistance of the conversion coating were studied through orthogonal test. The optimal range of different parameters for lanthanum conversion are as follows： La（NO3）3＆#183;6H2O10-15g/L, H2O210mL/L, NaF0.5g/L, temperature 70 ℃, and time10-30 min. Both film forming temperature and time have great effects on corrosion resistance of the conversion coating. The addition of NaF is beneficial to film formation. The area fraction of white rust on lanthanum conversion coating obtained under the optimal conditions is 15% after neutral salt spray test for 3 periods, showing better corrosion resistance than that of the unpassivated Zn–2wt%Al alloy coating.

关 键 词：锌–铝合金 热浸镀 镧盐转化 耐蚀性 

分 类 号：TQ153.2[化学工程—电化学工业] TG174.4[金属学及工艺—金属表面处理]