AZ91镁合金表面Ce-Mn复合转化膜室温制备及其耐蚀性研究

Preparation and Corrosion Resistance of Ce-Mn Conversion Coating on AZ91 Magnesium Alloy at Room Temperature

室温下,以Ce(NO33)为主盐、KMnO4为氧化剂、氟化物为成膜促进剂在AZ91镁合金表面制备了Ce-Mn复合转化膜,分析了化学转化处理不同时间形成的转化膜的微观形貌和成分,研究了转化膜的耐腐蚀性能。结果表明:氟化物的加入可实现室温下快速成膜,膜层主要由Al,Ce,Mn和O元素组成,宏观上完整均匀,但存在微观裂纹;处理2min所得的转化膜表现出较好的耐腐蚀性能,其自腐蚀电流密度比镁合金基材降低了1个数量级。最后,探讨了成膜机制及膜层的耐蚀机理。

Ce-Mn conversion coating was prepared on AZ91 magnesium alloy at room temperature by dipping the specimens into solutions containing Ce（NO3）3, KMnO, and fluoride. The surface morphology, composition and corrosion resistance of the conversion coating which was treated for various time were investigated. The results show that Ce-Mn conversion coating can be formed rapidly at room temperature by adding a little fluoride. The conversion coating which is mainly composed of Al,Ce, Mn and O elements is integrated and uniform from macroscopic view but contains some microcosmic cracks. The conversion coating formed in 2 minutes shows better corrosion resistance that its corrosion current density decreases by an order of magnitude compared with magnesium alloy substrate. Finally, the formation mechanism and anticorrosion mechanism of the conversion coating were discussed.