采用表面机械研磨(surface mechanical attrition treatment, SMAT)技术对AZ31镁合金进行前处理,以氢氧化钙和磷酸二氢钙为前驱物,在AZ31镁合金表面通过溶胶-凝胶(sol-gel)法制备了羟基磷灰石涂层.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对涂层表面形貌、截面进行了分析表征,利用电化学工作站测试了该涂层的在生理盐水中的动电位极化曲线.结果表明,SMAT后样品上的HAP的结晶性增强,HAP涂层厚度由8 μm增加到18 μm,而且HAP涂层与SMAT处理过的基体间结合强度明显提高.动电位极化测试表明SMAT后样品的HAP涂层自腐蚀电流密度降低了50%,腐蚀电位正移了56.1 mV,抗腐蚀性能明显增强.
In this paper, the surface mechanical attrition (SMAT) had been used as the pre-treatment technology and Ca(OH)2 and Ca(H2PO4)2·H2O had been used as raw materials.A hydroxyapatite coating had been prepared on the surface of AZ31 magnesium alloy using a sol-gel technique.The phases, surface morphologies and the adhesion of the hydroxyapatite coating were detected by X-ray diffraction, scanning electron microscopy, 3D optical profiler and cross cutting test.Potentiodynamic polarization curves were tested using electrochemical workstation in normal saline solution.The results indicate that the HAP coating shows the enhanced crystallinity after SMAT.The thickness of HAP coating increased from 8 to 18 μm and the bonding strength between the HAP coating and SMATed substrate is obviously improved.Dynamic potential polarization tests show the corrosion current density of HAP coating on SMATed sample was about 50% lower than that on original sample and the corrosion potential shifted by 56.1 mV to the positive direction, which indicate corrosion resistance of HAP coating on SMATed sample was significantly enhanced.
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