Mg2B2O5晶须增强AZ91D镁基复合材料在Cl-溶液中腐蚀行为

摘要

用电化学方法测量了Mg2B2O5晶须增强AZ91D镁基复合材料在3.5％ NaCl溶液中的开路电位、动电位极化曲线和交流阻抗,研究了晶须体积分数对镁合金基体耐腐蚀性能的影响,并利用SEM和XRD表征了腐蚀后复合材料表面的微观形貌和相组成.结果表明,随着Mg2B2O5晶须体积分数的增加,AZ91D镁基复合材料的耐腐蚀性逐渐提高.当硼酸镁晶须的体积分数为35％时,材料的自腐蚀电位提高0.2V以上,自腐蚀流密度降低了1个数量级;SEM测试表明,复合材料表面生成了一层晶须增韧的腐蚀钝化膜,对基体起到保护作用.%The open circuit potential tests,potentiodynamic polarization curves and electrochemical impedance spectrum(EIS) of Mg2B2O5w/AZ91D magnesium matrix composites in 3.5％ NaCl solution were investigated by the electrochemical method and the impact of the whisker volume fraction on the corrosion resistance of magnesium matrix composites studied.The surface morphology and the phase composition of the composite after corrosion test were characterized by SEM and XRD.The results show that the corrosion resistance of AZg1D magnesium matrix composites is improved gradually with the increase of the volume fraction of Mg2B2O5 whisker.When the volume fraction of magnesium borate whisker was 35％,the corrosion potential of the matrix composite material increases by 0.2 V,and the corrosion current density decreases an order of magnitude.SEM tests indicate that the surface of the composite material produces a layer of whisker toughened by the corrosion passivation film,which shows a protective effect on the substrate.