H_2O_2对AZ91D镁合金表面铈转化膜形成及耐腐蚀性能的影响研究

Influence of H_2O_2 on formation and corrosion protection properties of cerium conversion coatings on AZ91D magnesium alloys

选择AZ91D镁合金为实验材料,利用扫描电镜和能谱分析、Tafel曲线和阻抗谱等分析手段,结合点蚀实验和转化液滴定分析实验,研究了H2O2在铈盐转化膜形成过程中的作用及对铈转化膜耐腐蚀性能的影响。结果表明,H2O2的作用主要表现为复杂还原剂、氧化剂、晶型增长抑制剂。Ce∶H2O2的摩尔比为1∶3时,可使形成的无定形Ce(O2)(OH)2中包含数量较多但尺寸较小的纳米级CeO2晶体颗粒,赋予转化膜较好的耐腐蚀性能。

AZ91D magnesium alloy was selected as the Basement. SEM, EDS, Tafel, EIS, spot-rot and titrations of cerium-based conversion coatings solutions were adopted to investigate the role of H2O2 in the deposition of conversion coatings and influence on corrosion protection properties of coatings. In the ease of coating deposition, H2O2 serves as a complex agent, an oxidant, a crystallization inhibitor. H2O2 added suitably amount of, such as Ce ： H2 O2 （tool ratio） is 1 ： 3, can endow eoatings with good eorrosion protection properties by promo- ting the generation of amorphous material Ce（O2）（OH）2 containing a great number of nano-sized crystallites of CeO2.