TiB_(2)/A356复合材料在NaCl溶液中的电化学腐蚀行为  

Electrochemical Corrrosion Behavior of TiB_(2)/A356 Composites in NaCl Solution

作　　者：李永飞 徐佐 朱志华 贾超航 李天 李振 张兴明 范金龙 LI Yong-fei;XU Zuo;ZHU Zhi-hua;JIA Chao-hang;LI Tian;LI Zhen;ZHANG Xing-min;FAN Jin-long(CITIC Dicastal Co.,Ltd.,Qinhuangdao 066011,Hebei,China)

机构地区：[1]中信戴卡股份有限公司,河北秦皇岛066011

出　　处：《铸造》2021年第4期444-448,共5页Foundry

摘　　要：采用动电位极化和电化学阻抗试验研究了不同颗粒含量原位自生TiB_(2)/A356复合材料在3.5%NaCl溶液中的腐蚀行为。结果表明:TiB_(2)颗粒的引入,可以提高A356合金的腐蚀电位,降低腐蚀速率,增强其耐蚀性;电荷转移电阻和腐蚀产物的扩散电阻共同决定腐蚀反应速率,进而决定合金耐腐蚀性能的高低。复合材料耐蚀性能的提高,一方面由于TiB_(2)颗粒的引入显著细化基体晶粒,使得合金表面氧化膜的生成速度加快、氧化膜的稳定性提高;另一方面沿晶界均匀分布的TiB_(2)颗粒阻断了晶界位置Si、Mg2Si与Al基体组成的腐蚀电偶的活化通道,降低合金的腐蚀速率,提高腐蚀抗力。随着颗粒含量的增多,复合材料的腐蚀敏感性降低,而且TiB_(2)颗粒团聚将削弱材料抗腐蚀性能。2%TiB_(2)/A356复合材料的耐蚀性最好。Corrosion behavior of in situ TiB_(2)/A356 composites with different mass fraction of TiB_(2) particles in 3.5%NaCl solution was studied by potentiodynamic polarization and electrochemical impedance testing.The results indicate that the introductionof TiB_(2) particles can increase corrosion potential of the matrix,reduce the corrosion speed and raise the corrosion resistance of alloy.The corrosion reaction speed was determined by the charge-transfer resistance and the diffusion resistance of corrosion products.There are two reasons for the improved corrosion resistance of composite materials:on the one hand,the introduction of TiB_(2) particles significantly refined the matrix grains,which accelerated the formation rate of the oxide film on the alloy surface and improved the stability of the oxide film;on the other hand,the TiB_(2) particles were distributed uniformly along the grain boundary,which blocked the activation channel of the corrosion couple composed of Si,Mg2Si and Al matrix at the grain boundary.The corrosion rate of the alloy was reduced while the corrosion resistance was increased.The corrosion sensitivity of composites decreased with increa-singthe content of TiB_(2) particles,and the agglomeration of TiB_(2) particles would weaken the corrosion resistance of the composites.The 2%TiB_(2)/A356 composite exhibited the best corrosion resistance.

关 键 词：TiB_(2)/A356复合材料 原位自生 极化曲线 电化学阻抗 耐蚀性 

分 类 号：TG146.2+1[一般工业技术—材料科学与工程]