Mo_2C对Ti(C,N)基金属陶瓷腐蚀性能的影响

通过静态浸泡腐蚀和动电位极化两种方法,研究了Mo2C对Ti(C,N)基金属陶瓷在NaOH溶液中腐蚀性能的影响。实验结果表明:Ti(C,N)基金属陶瓷的耐蚀性明显优于WC-Co硬质合金;添加Mo2C可以大幅度提高Ti(C,N)基金属陶瓷的机械性能,硬度从91.2到94.0 HRA和抗弯强度从930到1 350 MPa,但会降低金属陶瓷的耐蚀性能;由于Mo2C的加入,会使金属陶瓷的动电位极化曲线出现两个钝化区,但是两个钝化区域的电流均未达到真正的钝化电流(10-5A/cm2),因而这些钝化现象均为伪钝化;在经动电位极化后的试样表面,粘结相Ni和白色的内环相均会被腐蚀,其中内环相为富Mo的(Mo,Ti)(C,N)固溶体,其耐腐蚀性较未溶的Ti(C,N)芯更差。随着Mo2C添加量的提高,内环形相的厚度随之会增加,从而降低了Ti(C,N)基金属陶瓷的耐蚀性能。

Effect of Mo2C on Corrosion Behavior of Ti(C,N)-based Cermets

The effect of Mo2C on corrosion behavior of Ti（C,N）-based cermets in NaOH alkali solution was studied by static corrosion and electrochemical corrosion.The results show that the corrosion resistance of Ti（C,N）-based cermets is obviously better than that of cemented carbides.The Mo2C addition could improve mechanical properties of cermets greatly,as the hardness increases from 91.2 to 94.0 HRA and transverse rupture strength increases from 930 to 1 350 MPa,but it also decreases the corrosion resistance of cermets.As the Mo2C addition added,there are two passive regions for the polarization curves.But those passive regions are all pseudopassivation which could not reach the real passivation current（10-5 A/cm2）.It could be found on electrochemical corrosion surface that the binder Ni and the inner rims are all corroded.The inner rims is（Mo,Ti）（C,N） solid solution which is poor in corrosion resistance.With the increase of Mo2C addition,the thickness of inner rims increases.So the corrosion resistance of Ti（C,N）-based cermets decreases with the Mo2C addition.