铈单盐浓度对AZ91镁合金表面稀土转化膜的影响

Effect of Cerium Mono-Salt Concentrations on the Rare Earth Conversion Coatings on AZ91 Magnesium Alloys

镁合金表面稀土转化膜应用前景广阔,但文献报道的稀土单盐浓度相差较大,为获得最佳单盐浓度,在不同钵盐浓度条件下在AZ91镁合金表面制备稀土转化膜,用扫描电镜、X射线衍射仪、浸泡腐蚀试验和电化学分析等手段和方法研究了转化膜的形貌、成分、结构和性能。结果表明:富钵稀土转化膜主要是由CeO2、CeMg以及少量的Ce5Mg41共同构成;在成膜温度40℃、成膜时间20min的条件下,制备镁合金稀土转化膜的最佳Ce(NO3)3浓度为0.02mol/L。

Rare earth conversion coatings on magnesium alloy present wide application prospect, but the concentrations of single rare earth salt were much different. In order to obtain the optimal concentration of single rare earth salt, the rare earth conversion coatings under the condition of different concentrations of Ce salt solution were fabricated on AZ91 magnesium alloy surface. The microstructure, chemical composition and properties of the conversion coatings were investigated by scanning electron microscope, X - ray diffractometer ( XRD), immersion tests and electrochemical tests, respectively. Results showed that the Ce - rich conversion coatings were consisted of CeO2, CeMg and a few Ce5 Mg41 phases. Under 40 X. of film - forming temperature and 20 min of film - forming time, the optimal concentration of Ce ( NO3) 3 for preparing conversion coating on Mg alloy was 0.02 mol/L.