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利用Tafel曲线、阻抗谱分析、NaCl水溶液点滴实验和扫描电镜观察等手段,研究了温度对AZ91D镁合金的植酸转化膜表面形貌及耐蚀性的影响.结果表明:当温度为25℃～35℃时转化膜的耐蚀性较好,温度过高或过低都会使转化膜的耐蚀性变差;转化膜表面的裂纹是在干燥处理过程中由于表层转化膜体积收缩而产生的;镁合金表面形成的植酸转化膜应属于电子导体,该层膜的形成阻碍了腐蚀介质与镁合金基体的接触,同时抑制腐蚀产物的扩散,对镁合金起到了较好的防护作用.
The effects of temperature on the morphology and corrosion resistance of phytic acid conversion coatings on AZ91D magnesium alloy were investigated by means of Tafel curve, impedance spectroscopy, NaCl aqueous solution drip test and scanning electron microscope observation. The results show that when the temperature is 25 ℃ ~ The corrosion resistance of the conversion coating at 35 ℃ is better. If the temperature is too high or too low, the corrosion resistance of the conversion coating deteriorates. The crack on the surface of the conversion coating is due to the volume shrinkage of the surface conversion coating during the drying process. The phytic acid conversion coating formed on the surface of magnesium alloy should belong to the electronic conductor. The formation of this layer hinders the contact between the corrosion medium and the magnesium alloy matrix and inhibits the diffusion of corrosion products, which plays a good protective role on the magnesium alloy.