镁合金表面钼−钛−锰导电转化膜高温高湿条件下的失效分析  

Failure analysis of conductive Mo-Ti-Mn conversion coating on magnesium alloy in high-temperature and high-humidity environment

作　　者：雷华[1] 易爱华 廖忠淼 李文芳 张德忠 刘宁华 LEI Hua;YI Aihua;LIAO Zhongmiao;LI Wenfang;ZHANG Dezhong;LIU Ninghua(Guangzhou City Polytechnic,Guangzhou 510405,China;School of Materials Science and Engineering,Dongguan University of Technology,Dongguan 523808,China;Academy of Machinery Wuhan Research Institute of Materials Protection Co.,Ltd.,Wuhan 430030,China;Guangzhou Sanfu New Material Technology Co.,Ltd.,Guangzhou 510700,China)

机构地区：[1]广州城市职业学院,广东广州510405 [2]东莞理工学院材料科学与工程学院,广东东莞523808 [3]中国机械总院集团武汉材料保护研究所有限公司,湖北武汉430030 [4]广州三孚新材料科技股份有限公司,广东广州510700

出　　处：《电镀与涂饰》2024年第12期83-91,共9页Electroplating & Finishing

基　　金：广东省普通高校重点科研平台和项目──重点领域专项(2024ZDZX3095);广东省教育科学规划课题(高等教育专项)(2024GXJK930);广州市教育局羊城学者科研项目──学术带头人培养项目(2024312013);广州城市职业学院校级科学项目博士专项(KYBS2024004)。

摘　　要：[目的]分析AZ91D镁合金表面Mo-Ti-Mn导电转化膜在“双85”(指温度85℃、相对湿度85%)湿热环境中的失效行为,为开发性能更好的导电膜层提供依据。[方法]研究了Mo-Ti-Mn转化膜在湿热试验不同时间后表面形貌、耐蚀性、表面接触电阻(ECR)及禁带宽度的变化情况。[结果]随着湿热试验时间的延长,Mo-Ti-Mn转化膜的颜色逐渐变浅,微裂纹变宽,耐蚀性变差,接触电阻和禁带宽度增大。[结论]在湿热环境下,水汽渗入膜层的微裂纹中,与膜层和镁合金基体发生电化学反应。随着时间的推移,原本致密的膜层开始变得疏松,电化学腐蚀反应加速,最终丧失导电性和防护性。[Introduction]The failure behavior of Mo-Ti-Mn conductive conversion coating on the surface of AZ91D magnesium alloy under“dual 85”damp-heat condition(i.e.temperature 85℃and relative humidity 85%)was analyzed,to provide a basis for the development of better-performing conductive coatings.[Method]The changes in morphology,corrosion resistance,electrical contact resistance(ECR),and bandgap width(Eg)of Mo-Ti-Mn conversion coating after different durations of damp-heat test were studied.[Result]With the extending of damp-heat testing time,the color of Mo-Ti-Mn conversion coating was gradually lightened,the micro-cracks on its surface were widened,the corrosion resistance of the conversion coating was deteriorated,and its ECR and Eg were increased.[Conclusion]In the high-temperature and high-humidity environment,water vapor penetrates into the micro-cracks of conversion coating,and reacts electrochemically with conversion coating and magnesium alloy substrate.The originally compact conversion coating becomes loose with the extending of damp-heat testing time,accelerating the electrochemical corrosion reactions,and the conversion coating ultimately loses its conductivity and protective capability.

关 键 词：镁合金 化学转化 钼−钛−锰 高温高湿环境 失效分析 

分 类 号：TQ153.6[化学工程—电化学工业]