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用电化学方法测量了Mg_2B_2O_5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Mg_2B_2O_5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 potentials, potentiodynamic polarization curves and AC impedances of AZ91D magnesium matrix composites reinforced with Mg_2B_2O_5 whiskers in 3.5% NaCl solution were measured by electrochemical method. The effects of whisker volume fraction on the corrosion resistance of magnesium matrix were investigated. The microstructure and phase composition of the surface of the composite after corrosion were characterized by SEM and XRD. The results show that the corrosion resistance of AZ91D magnesium matrix composites increases with the increase of volume fraction of Mg_2B_2O_5 whiskers. When the volume fraction of magnesium borate whisker is 35%, the self-corrosion potential of the material is increased by 0.2V and the self-corrosion flow density is reduced by one order of magnitude. The SEM test shows that the surface of the composite material forms a layer of whisker toughening corrosion Passivation film, play a protective role on the substrate.