真空烧结纳米La_2O_3掺杂MoSi_2复合涂层的高温摩擦学性能

High Temperature Tribological Properties of Nano La_2O_3-Doped MoSi_2 Composite Coatings Sintered in Vacuum

采用高温真空烧结法在高速钢基体表面上制备了纳米氧化镧掺杂二硅化钼基复合涂层;考察了温度(200~800℃)、纳米La_2O_3含量(1%、3%和5%)(质量比)对MoSi_2基复合涂层高温摩擦学性能的影响规律;采用X射线衍射表征了MoSi_2基复合涂层高温摩擦磨损前后的微结构,探讨了复合涂层的高温摩擦磨损机理。研究结果表明纳米La_2O_3掺杂MoSi_2基复合材料摩擦学性能在低温(200℃)和高温(800℃)下纳米La_2O_3含量为3%时较好,摩擦系数为0.1。通过引入纳米La_2O_3可有效地改善Mo Si2的高温摩擦学性能,其磨损机理主要为磨粒磨损、粘着磨损和氧化磨损的复合磨损。

The MoSi2 composite coatings were synthesized and doped with La203 nano-particIes by high tem- perature sintering in vacuum on substrate of high speed steel. The influence of the content of La203 nano-particles on the high temperature tribological behavior of the coatings was investigated with X-ray diffraction （XRD） and conventional mechanical probes. The results show that depending on its content, doping of La203 significantly affected the high temperature tribological properties of the coatings. For example ,as the La203 contentincreased ,the com- pactness, hardness and wear-resistance of the coatings changed in an increase-decrease mode, and the friction coefficient varied in a decrease-increase way; 1% and/or 5% （wt） of La203 significantly increased the wear-rate. Doped at 3 % of La203, the MoSi2 coating, with a friction coefficient of 0.1, displayed an excellent tribological performance at 200℃ and 800℃, respectively. A combination of abrasive, adhesive and dominate oxidative wear was responsible for the wear mechanisms.