超音速等离子喷涂NiCrCr3C2/Mo复合涂层的高温摩擦磨损性能*

采用超音速等离子喷涂制备了NiCr-Cr3C2/Mo复合涂层,借助扫描电子显微镜(SEM)、能谱仪(EDS)、显微硬度计、高温摩擦磨损试验机等手段,研究了涂层的微观组织、显微硬度及涂层在25、300、500、750℃下的摩擦磨损性能。结果表明:制备的NiCr-Cr3C2/Mo复合涂层Mo相分布均匀,组织致密、硬度高;温度对涂层的摩擦因数影响显著,随温度的升高,摩擦因数呈先下降后上升再下降的趋势,750℃时因摩擦界面生成MoO3减摩相使摩擦因数最低;NiCr-Cr3C2/Mo复合涂层在高温下以氧化疲劳剥落为主要失效机制,涂层表面复合氧化膜的形成特点将直接影响涂层的摩擦磨损性能,MoO3的形成是显著提高涂层减摩效果的主要因素。

Tribological Behavior of Supersonic Plasma Spraying NiCrCr3C2/Mo Composited Coatings at High Temperature

NiCr-Cr3C2/Mo composited coating was prepared by the supersonic plasma spraying system.The microstructure and composition of the coating were characterized by SEM and EDS,and the hardness and tribological behavior at 25,300,500 and 750℃ were measured by a micro-hardness tester and high temperature tribometer.The results show that Mo phase is uniformly distributed in the coating that is dense with high hardness.The temperature exhibits a marked effect on the friction coefficient of the coating.The friction drops then rises and drops again with increasing temperature and it attains the lowest when MoO3 phase forms at the frictional pairs interface at 750℃.Oxidation-fatigue spalling is the main failure mechanism of the coating at high temperature.The friction and wear properties of the coating are directly affected by the characteristics of the composite oxide that forms on the surface of the coating.The MoO3 phase is the main factor to increase friction-reducing effect of the coating.