w(Co)/w(Ni)对Ti(C,N)基金属陶瓷高温氧化和耐腐蚀性能的影响

Effects of w(Co)/w(Ni) ratio on high-temperature oxidation and corrosion resistant behavior in Ti(C,N)-based cermets

采用粉末冶金法制备Ti(C,N)基金属陶瓷,研究粘结相Co与Ni的含量比对材料组织结构和性能的影响,并系统研究材料在高温环境和酸性水溶液中的氧化与腐蚀行为。结果表明,w(Co)/w(Ni)=1的金属陶瓷材料T3具有优异的综合力学性能,其抗弯强度与硬度(HRA)分别为1 749 MPa和93.8;随着Ni的添加,材料在H_2SO_4溶液中的耐腐蚀性能显著提高,其中的T3经120 h浸泡腐蚀后质量损失率为0.074 5%,粘结相和部分环形相的溶解为金属陶瓷在酸溶液中的主要腐蚀行为。随w(Co)/w(Ni)的值减小,材料阳极极化过程中不同钝化区出现融合,证明Ni含量增加可促进元素向粘结相中的固溶,T3材料具有优异的耐腐蚀性能,自腐蚀电流密度为3.356 6×10^(-7) A/cm2。表面积为2.5 cm2的Ti(C,N)基金属陶瓷,在900℃高温静态空气中氧化10 h后,质量增加量均小于1 mg,材料的氧化机理以粘结相优先氧化和富Ti、W固溶相的氧化腐蚀为主。

The effects of Co and Ni binder ratio on microstructure and properties in Ti(C,N)based cermets has been studied.The corrosion behaviors of cermets in high temperature and acid solution have been analyzed systematically.The results indicate that cermet with w(Co)/w(Ni)ratio of 1 has excellent mechanical properties,which TRS and hardness are 1 749 MPa and 93.8(HRA),respectively.The corrosion resistant of cermets in H2SO4 acid solution increases obviously with adding Ni into binder phase,whereas the mass loss of T3 cermet with w(Co)/w(Ni)ratio of 1 is 0.074 5%after immersion for 120h.The corrosion mechanisms of cermets in acid solution are the dissolution of binder phase and partly rim phases.The passive regions in anodic polarization curves appear combination with the decrease of w(Co)/w(Ni)ratio,which is proved that the increase of Ni content can promote the solid solution of the elements to the binder phase.The T3 cermet has excellent corrosion resistance,and the self corrosion current density is 3.356 6×10^-7 A/cm^2.Finally,after oxidized in static air for 10 h under 900℃,the mass losses of all cermets with surface area of 2.5 cm^2 are lower than 1mg.Moreover,the corrosion behaviors of cermets in high temperature are the prior oxidation of binder phase and the oxidation of Ti,W-riched solid solution phases.