AZ 31镁合金稀土转化成膜及其耐蚀性能的研究

Forming and Corrosion Resistance of Rare Earth Conversion Coating on AZ 31 Magnesium Alloy

对AZ 31镁合金表面稀土转化处理的成膜工艺进行了初步研究。分析了不同的成膜工艺参数(稀土盐的质量浓度、成膜时间、成膜温度)对稀土转化膜的形成以及耐蚀性能的影响。扫描电镜分析不同成膜工艺形成的稀土转化膜表面形貌;用极化曲线研究转化膜的电化学腐蚀行为。结果表明:当转化液中铈的质量浓度为21.7g/L时,膜的耐蚀性最好;成膜时间、成膜温度对膜的耐蚀性也有不同程度的影响。在本文研究的时间范围内,处理时间长能获得更好的耐蚀性。

In this paper, the forming technological process of rare earth conversion coating on AZ 31 magnesium alloy is preliminarily studied. The effects of various technical parameters, such as mass concentration of rare earth salts, temperature and time on the formation and corrosion properties of the coating are researched in detail. Different morphologies of the rare earth conversion coatings formed by different processes are analyzed with SEM, and the electrochemical corrosion behavior of the conversion coatings is analyzed with polarization curves. The results show that the corrosion resistance is the best when the mass concentration of cerium is 21. 7 g/L, and the time and temperature for coating formation also affect the corrosion resistance of the coatings to different extents. Within our researching time range, the longer the immersion time is used, the better the corrosion resistance will be.