TC21钛合金表面无氢渗碳层耐磨性分析

将经过预处理的TC21钛合金试样置入真空渗碳炉中进行渗碳。分别用X射线衍射(XRD)、扫描电子显微镜(SEM)及显微维氏(HV)硬度仪、摩擦磨损试验机,对渗碳层的物相结构、组织形貌、硬度和耐磨性进行分析。结果表明:经渗碳处理后,通过渗层组织可判定没有氢化物,XRD未检测发现氢化物及含H相,出现了Ti C等碳化物相,表面硬度提高了2.66倍。渗碳前Ti/Ti对磨的摩擦系数约为0.6,渗碳后Ti C/Ti C的摩擦系数约为0.23,渗碳体与原始表面的摩擦系数介于二者之间。TC21钛合金对磨两方经渗碳处理,改善了摩擦性能;如Ti/Ti部件对磨时,渗碳方可提高耐磨性,非渗碳件在与渗碳件对磨中,加剧了非渗碳件的磨损。渗碳也改变了TC21钛合金部件之间的摩擦状态,TC21基体由Ti基/Ti球之间的粘着磨损变为Ti基/Ti C球磨粒磨损+剥层磨损。

Wearability Analysis of Hydrogen-free Carburized Coating on TC21 Titanium Alloy Surface

TC21 titanium alloy specimens after pretreatment were carburized in a vacuum carburizing furnace. The microstructure, phases, hardness and wearability of the carburized coating were analyzed by SEM, XRD, HV hardness tester and friction-wear test machine, respectively. Results show that after carburization, no hydride can be determined by carburized layer tissue, no hybrids or H-containing phase are observed in the coating, while TiC and other carbide phases appear. The hardness of the alloy surface after carburizing increases by 2.66 times. The friction coefficient of Ti/Ti is 0.6, after carburization that of TiC/TiC is 0.23, and that of Ti/TiC is between Ti/Ti and TiC/TiC. After carburizing treatment, frictional properties of TC21 titanium alloy are improved. When Ti/Ti part is grinding each other, the carburized part can improve the wear resistance. Wear of noncarburized part becomes serious when it is grinding with a carburized part. Carburizing also changes the friction state between TC21 titanium alloy components, i.e. from adhesion wear between Ti substrate and Ti ball, to grain wear and delamination wear between Ti substrate and TiC ball.