镁合金汽车轮毂表面转化膜的致密化与耐蚀性能研究  

Study on Densification and Corrosion Resistance of Conversion Coatings on Magnesium Alloy Wheel Hubs Surface

作　　者：何伟丽[1] 张庆丰 睢利铭 罗新民 HE Wei-li;ZHANG Qing-feng;SUI Li-ming;LUO Xin-min(Department of Mechanical and Electrical Engineering,Zhumadian Vocational and Technical College,Zhumadian 463000,China;School of Traffic Engineering and Vehicle Engineering,Henan Institute of Technology,Xinxiang 453000,China;School of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450001,China)

机构地区：[1]驻马店职业技术学院机电工程系,河南驻马店463000 [2]河南工学院车辆与交通工程学院,河南新乡453000 [3]郑州大学材料科学与工程学院,河南郑州450001

出　　处：《材料保护》2021年第3期113-120,共8页Materials Protection

基　　金：河南省科技计划项目(192102210063)资助。

摘　　要：为了在镁合金汽车轮毂表面制备成本低、环保和耐腐蚀的转化膜,以提升其耐蚀性能,采用扫描电镜、能谱分析仪和电化学工作站等研究了后续致密化处理温度和时间对Mg-5.2Al-0.5Mn-1.8Ca合金表面铈转化膜形貌和电化学性能的影响。结果表明:转化膜经磷酸盐致密化处理后其腐蚀电位正移、腐蚀电流密度减小、极化电阻增大,转化膜的耐腐蚀性能得到增强,且致密化温度为85℃时转化膜的耐腐蚀性能最好;随着致密化时间的延长,转化膜的腐蚀电位呈现先正向移动后负向移动特征,腐蚀电流密度先减小后增大,极化电阻先增大后减小,在致密化时间为60 s时,转化膜的腐蚀电位最正、腐蚀电流密度最小、极化电阻最大,具有最佳的耐蚀性能。致密化处理前的原始转化膜的耐腐蚀性能主要与表面裂纹和转化膜结构有关,致密化处理后其耐腐蚀性能主要与新形成的致密CePO_(4)膜层有关;在致密化温度为85℃、致密化时间60 s时,镁合金表面转化膜具有最佳的耐蚀性能。In order to improve the corrosion resistance of magnesium alloy wheel hub,a low-cost,environmentally friendly and corrosion-resistant conversion coating was prepared on the surface of magnesium alloy wheel hub.The effects of subsequent densification temperature and time on the morphology and electrochemical properties of cerium conversion film on Mg-5.2Al-0.5Mn-1.8Ca alloy were investigated by SEM,EDS and electrochemical workstation.Results showed that the corrosion potential of the conversion film after phosphate densification treatment moved forward,the corrosion current density decreased and the polarization resistance increased,therefore,the corrosion resistance of the conversion film was enhanced.The corrosion resistance of the conversion film was the best when the densification temperature was 85℃.With the extension of the densification time,the corrosion potential of the conversion film first moved forward and then moved negatively,the corrosion current density first increased and then decreased,and polarization resistance first increased and then decreased.When the densification time was 60 s,the corrosion potential of the conversion film was the most positive,the corrosion current density was the smallest,and the polarization resistance was the largest,which showed the best corrosion resistance.The corrosion resistance of the original conversion film before densification treatment was mainly related to the surface cracks and the structure of the conversion film,the corrosion resistance of the conversion film after densification treatment was mainly related to the newly formed dense CePO_(4) film.When the densification temperature was 85℃ and the densification time was 60 s,the conversion film had the best corrosion resistance.

关 键 词：镁合金 铈转化膜 致密化温度 致密化时间 耐蚀性能 

分 类 号：TG174[金属学及工艺—金属表面处理]