Self-healing Performance of Composite Coatings Prepared by Phosphating and Cerium Nitrate Post-sealing  

作　　者：林碧兰 LU Jintang 

机构地区：[1]School of Material Science and Engineering, Xiamen University of Technology [2]School of Material Science and Engineering, South China University of Technology

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2015年第4期813-817,共5页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Natural Science Foundation(No.501408517);the Natural Science Foundation of Fujian Province(No.2012J05099);the Pre-research Project of National Natural Science Fund of Xiamen University of Technology(No.XYK201410)

摘　　要：The phosphated and cerium nitrate post-sealed galvanized steel was firstly scratched to expose zinc layer and then placed in neutral salt spray （NSS） chamber for different durations. The microstructure and compositions of the scratches were investigated using SEM and EDS. The phases of the corrosion products were examined through XRD. The self-healing mechanism of the composite coatings was discussed. The experimental results show that the composite coatings have an excellent corrosion resistance. The corrosion products increase with corrosion time and finally cover the whole scratch. They contain phosphorous, cerium, oxygen, chloride and zinc, and are fine needle and exceedingly compact. The composite coatings are favorable self-healing. During corrosion, the self-healing ions such as Ce3＋, Ce4＋, PO43-, Zn2＋ in the composite coatings were dissolved, migrated, recombined, and covered the exposed zinc, impeding zinc corrosion. The self-healing process of the scratches on the composite coatings can be divided into three stages, about 2 h, 4 h, and 24 h, respectively.The phosphated and cerium nitrate post-sealed galvanized steel was firstly scratched to expose zinc layer and then placed in neutral salt spray （NSS） chamber for different durations. The microstructure and compositions of the scratches were investigated using SEM and EDS. The phases of the corrosion products were examined through XRD. The self-healing mechanism of the composite coatings was discussed. The experimental results show that the composite coatings have an excellent corrosion resistance. The corrosion products increase with corrosion time and finally cover the whole scratch. They contain phosphorous, cerium, oxygen, chloride and zinc, and are fine needle and exceedingly compact. The composite coatings are favorable self-healing. During corrosion, the self-healing ions such as Ce3＋, Ce4＋, PO43-, Zn2＋ in the composite coatings were dissolved, migrated, recombined, and covered the exposed zinc, impeding zinc corrosion. The self-healing process of the scratches on the composite coatings can be divided into three stages, about 2 h, 4 h, and 24 h, respectively.

关 键 词：zinc phosphate coating SELF-HEALING corrosion resistance cerium nitrate 

分 类 号：TG174.4[金属学及工艺—金属表面处理]