Ti_3SiC_2在水、乙醇及其混合溶液中的摩擦学行为研究

Tribological Behaviour of Ti_3SiC_2 in Water,Ethanol and Their Mixtures

目的考察新型可加工金属陶瓷材料Ti_3SiC_2在水基润滑系统(如水液压系统)及乙醇润滑系统(如乙醇燃料系统)中的摩擦学行为。方法利用中频热压烧结技术制备Ti_3SiC_2样品,用球盘接触模式SRV-1摩擦磨损试验机考察Ti_3SiC_2/Si_3N_4摩擦副的摩擦学行为,利用扫描电子显微镜、X-射线光电子能谱、X-射线衍射谱等分析材料的形貌和成分物相。结果 Ti_3SiC_2/Si_3N_4摩擦副在乙醇中具有较低的摩擦系数(0.14)和磨损率(10^(-7) mm^3/(N×m)),但在纯水中,其摩擦系数(0.54)和磨损率(10^(-4) mm^3/(N×m))均较高。乙醇中少量的水(5%)即可使Ti_3SiC_2/Si_3N_4的摩擦学性能恶化,乙醇中Ti_3SiC_2磨损表面为轻微犁沟效应,随着乙醇中水含量的增大,Ti_3SiC_2晶粒拔出和脱落造成的坑洞增加,因此磨损率迅速增大。纯水中呈现大量的坑洞,相应的磨损率也达到最大值。结论乙醇是Ti_3SiC_2/Si_3N_4摩擦副很好的低黏度流体润滑剂,在乙醇中,摩擦表面的高化学活性Si元素与乙醇发生了摩擦化学反应,生成的硅醇聚合物在摩擦接触界面形成了边界润滑,致使Ti_3SiC_2/Si_3N_4摩擦副在乙醇中具有优良的润滑和减磨作用。

Research on the tribological behavior of TiaSiC2, a new type of machinable cermet material, in water-based lu- brication systems （such as water hydraulic systems） and ethanol lubrication systems （eg, ethanol fuel systems）. Ti3SiC2 sample was prepared by applying medium frequency hot-pressed sintering technology. Tribological behavior of Ti3SiCE/Si3N4 friction pair was explored with SRV-1 friction-abrasion testing machine in ball-on-disc mode. Surface morphology and composition phase were analyzed with scanning electron microscopy （SEM）, X-ray photoelectron spectroscope （XPS） and X-ray diffraction spectrum. TiaSiCE/SiaN4 had low coefficient of friction （0.14） and wear rate （10-7 mm3/（N.m）） in ethanol but high coefficient of friction （0.54） and wear rate （10^-4 mm^3/（N.m）） in pure water. The tribological properties of Ti3SiC2/Si3N4 could be degraded by a small amount of water （5 vol.%） in ethanol. Worn surface of Ti3SiC2 in ethanol was characterized by slight ploughing effect. As the water content in ethanol increased, pits caused by Ti3SiC2 grain pullout and spalling increased, and thereby wear rate in- creased rapidly. A large number of pits were present in pure water, and corresponding wear rate reached the maximum as well. Ethanol is a good low-viscosity fluid lubricant for Ti3SiC2/Si3N4 friction pair. Highly chemically active Si element on friction surface of ethanol has frictional chemical reaction with ethanol. The generated silanol polymer forms boundary lubrication on frictional contact interface. As a result, Ti3SiC2/Si3N4 friction pair has excellent lubrication and antifriction effect in the ethanol.