Cr、V、Ta添加剂对超粗晶和特粗晶硬质合金电化学腐蚀行为的影响  

Effects of Cr,V,Ta additives on electrochemical corrosion behaviors of extra coarse and super extra coarse cemented carbides

作　　者：马鋆[1] 张立[1] 南晴[1] 解明伟[1] 冯于平[1] 雷霆[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083

出　　处：《粉末冶金材料科学与工程》2012年第6期825-832,共8页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金资助项目(51074189);国家支撑计划资助项目(2011BAE09B02);高等学校博士学科点专项科研基金资助项目(20100162110001)

摘　　要：以WC–8.4Co、WC–8.4Co–0.4Cr3C2、WC–8.4Co–0.4VC和WC–8.4Co–0.4TaC等4组超粗晶和特粗晶硬质合金为研究对象,采用Tafel曲线和电化学阻抗谱(EIS)研究4组合金在pH=1的H2SO4溶液、pH=7的Na2SO4溶液以及pH=13的NaOH溶液中的电化学腐蚀行为,采用扫描电镜观察合金的腐蚀表面。结果表明,与WC–8.4Co合金相比,在3种不同pH值腐蚀溶液中WC–8.4Co–0.4Cr3C2、WC–8.4Co–0.4VC和WC–8.4Co–0.4TaC合金的耐腐蚀性能均得到改善,Cr3C2改善合金耐腐蚀性能的效果最佳;4组合金在pH=13的NaOH溶液中的耐腐蚀性能均优于其在pH=1的H2SO4溶液中的耐腐蚀性能。合金腐蚀机理为:与溶液接触时,合金中Co粘结相优先腐蚀,产生活性溶解,同时WC发生局域腐蚀。The electrochemical corrosion behaviors of WC-8.4Co, WC-8.4Co-0.4Cr3C2, WC-8.4Co--0.4VC and WC-8.4Co-0.4TaC extra coarse and super extra coarse cemented carbides were investigated by means of Tafel curves and Nyquist plots. Electrochemical experiments were carried out in H2SO4 solution （pH=1）, Na2SO4 solution （pH=7） and NaOH solution （pH=13）. Corrosion surface of the alloys were observed by scanning electron microscopy （SEM）. The results show that, comparing with WC-8.4Co referential alloy, the corrosion resistances of WC-8.4Co4）.4Cr3C2, WC-8.4Co-q）.4VC and WC-8.4Co-0.4TaC alloys in all the three kinds of corrosion solutions are improved. Among the three additives, Cr3C2 demonstrates the strongest ability in the improvement of the corrosion resistance. All the four alloys exhibit better corrosion resistance in NaOH solution （pH=13） than that in H2SO4 solution （pH=1）. The corrosion mechanism is as following： while the alloy is in contact with the corrosion solution, a preferential corrosion and active dissolution take place in the Co binder phase and the corrosion reaction also takes place in the local region of WC grains.

关 键 词：超粗晶和特粗晶硬质合金 添加剂 电化学腐蚀 Tafel曲线 Nyquist图 

分 类 号：TF125.3[冶金工程—粉末冶金] TG135.5[冶金工程—冶金物理化学]