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研究了AZ91D镁合金的钼酸盐化学转化表面处理工艺,利用点滴法和极化曲线法测试转化膜的耐蚀性,用测厚仪测定膜层的厚度,用SEM、EDS和XRD研究转化膜的形貌、成分和结构并探讨了成膜机理。结果表明,当Na2MoO4、NaH2PO4、Ca(NO3)2浓度分别为30 g/L、25 g/L、4 g/L,pH为3,温度为40℃,转化时间为20 min时膜层耐蚀性最好,膜层主要由Mg2Mo3O8组成,自腐蚀电位比空白试样提高了58 mV,对铁红漆的附着力达到了4B级。
The chemical conversion treatment of molybdate surface of AZ91D magnesium alloy was studied. The corrosion resistance of the conversion coating was measured by spotting method and polarization curve method. The thickness of the coating was measured by thickness gauge. The conversion film was studied by SEM, EDS and XRD. Morphology, composition and structure of the film and discussed the film forming mechanism. The results showed that when the concentration of Na2MoO4, NaH2PO4 and Ca (NO3) 2 were 30 g / L, 25 g / L, 4 g / L, pH 3, the temperature was 40 ℃ and the conversion time was 20 min, The best film, the film is mainly composed of Mg2Mo3O8, self-corrosion potential than the blank sample increased by 58 mV, iron red paint adhesion reached 4B level.