Sr元素添加对铝硅合金电化学腐蚀行为的影响

摘要

The changes of the surface morphology by electrochemical corrosion processing,open circuit potential,potentiody-namic polarization cure were investigated on different amount Sr addition with electrochemical analysis,scanning electron microscopy and EDS.The result indicated that pitting corrosion occurred for Al-Si alloy as the corrosion of Cl-.Pitting corrosion of no Sr addi-tion alloy deepened into corrosion crevice while the 0.04% Sr addition alloy developed into longitudinal deepening and spreading of pitting corrosion with extension of corrosion time.The minor addition of Sr varied the morphology of eutectic Si from the flake-like primary silicon to fibrous eutectic Si,reduced open circuit potential on the one hand and oxidized Al to passive film,weakened the effect of Cl-on pitting,reduced pitting corrosion damage on the other hand.The best Sr addition amount was 0.1% in 0.1M HCl solution.%利用电化学测试、扫描电镜和能谱分析等方法,对不同 Sr 元素添加量合金在1 M HCl 溶液中电化学腐蚀表面形貌的变化以及开路电位和动电位极化曲线进行了研究。结果表明,由于 Cl-的侵蚀作用,铝硅合金在1 M HCl中发生点蚀破坏,随着腐蚀时间的延长,未添加 Sr 元素合金的点蚀扩展并形成腐蚀缝隙,而经0.04%Sr变质的合金则保持点蚀的纵向加深与扩展。微量 Sr 元素的加入,一方面,促使铝硅合金中片状初生硅转变为纤维状共晶硅,使开路电位负移；另一方面,促进铝氧化,形成钝化膜,减缓Cl-侵蚀作用,增强合金耐点蚀性。在0.1 M HCl溶液中,Sr元素的添加量为0.1%时,ZL102合金的耐腐蚀性最佳。