草酸预处理AM50镁合金表面快速原位制备 蒸汽Mg−Al LDH涂层的耐蚀性

Corrosion resistance of rapidly formed in-situ steam Mg−Al LDH coating on AM50 Mg alloy pretreated with oxalic acid

通过暴露合金表面的金属间化合物(β-Mg17Al12和AlMn),研究草酸(OA)酸洗对AM50镁合金表面原位蒸汽Mg−Al层状双氢氧化物(LDH)涂层成膜机制和耐蚀性的影响。结果表明,OA预处理使镁合金表面金属间化合物比例显著增加,Mg−Al LDH在Al−Mn相周围成核并生长。当酸洗时间为45 s时,所得LDH涂层的厚度最大、耐蚀性最佳,与基体相比,其腐蚀电流密度降低3个数量级。最后,提出了AM50镁合金表面Mg−Al LDH涂层的成膜机制。

The effect of oxalic acid(OA)etching on the formation mechanism and corrosion performance of in-situ steam Mg−Al layered double hydroxide(LDH)coatings on AM50 Mg alloy was investigated by exposing the intermetallic compounds(β-Mg17Al12 and AlMn)on the surface of the alloy.The results demonstrated that the presence of OA led to an increased fraction of intermetallic compounds on the Mg substrate.Mg−Al LDH nucleated and grew around the Al−Mn phase.The best corrosion resistance of LDH coating was obtained with the maximum thickness at a pickling time of 45 s,and the corrosion current density was reduced by three orders of magnitude compared to the substrate.Finally,the formation mechanism of Mg−Al LDH coating on AM50 Mg alloy was proposed.