Ni3Al基涂层与不同材料配副时宽温域的摩擦学行为

采用等离子喷涂法制备Ni₃Al基涂层，分别以316L和Al₂O₃为摩擦偶件，考察25~800 ℃内摩擦偶件材料对涂层摩擦学行为的影响. 结果表明:在软金属Ag析出、BaF₂/CaF₂脆-塑性转变和摩擦氧化协同作用下，随温度升高Ni₃Al/316L和Ni₃Al/Al₂O₃摩擦副的摩擦系数和磨损率具有一致的变化规律，且Ni₃Al/Al₂O₃摩擦副性能更佳. 25 ℃时，涂层与316L对摩时发生黏着磨损和磨粒磨损，而与高硬度的Al₂O₃对摩时发生脆性剥层和磨粒磨损，使涂层表面更粗糙导致较高的摩擦系数；Al₂O₃热导率较低，高接触应力作用下产生的大量摩擦热不能及时耗散，剥落材料贮存于剥落坑或黏附于磨损表面，使Ni₃Al/Al₂O₃摩擦副具有较低的磨损率. 200~600 ℃时，高硬度的Al₂O₃对涂层的犁削作用较强导致Ni₃Al/Al₂O₃摩擦副具有高的摩擦系数；而涂层在Al₂O₃碾压下发生塑性变形，使其具有较低的磨损率. 800 ℃时，高硬度的Al₂O₃促使磨损表面形成高氧化物含量的润滑膜，使Ni₃Al/Al₂O₃摩擦副具有低的摩擦系数和高的磨损率. 

Tribological Behaviors of Ni3Al-Based Coating Coupled with Different Counterpart Materials in Wide Temperature Range

The Ni₃Al based composite coating was prepared by plasma spraying. The influences of 316L and Al₂O₃ counterpart material on the tribological behaviors of the coating at 25 ℃ to 800 ℃ were investigated. The results showed that under the synergistic action of precipitation of soft metal Ag, brittle-plastic transformation of BaF₂/CaF₂ and tribo-oxidation, the friction coefficient and wear rate of Ni₃Al/316L and Ni₃Al/Al₂O₃ tribo-pairs had the similar trend with the increase of temperature, and the Ni₃Al/Al₂O₃ tribo-pairs had better performance. At 25 ℃, the coating coupled with 316L adhesive wear and abrasive wear occurred, while brittle peeling and abrasive wear occurred when the coating coupled with Al₂O₃ of high hardness, resulting in rougher coating surface and higher friction coefficient. However, the thermal conductivity of Al₂O₃ was low, and a large amount of frictional heat generated under the action of high contact stress cannot be dissipated rapidly. The stripped material was stored in the peeling hole or adhered to the worn surface, resulting in a lower wear rate of Ni₃Al/Al₂O₃ friction pair. At 200~600 ℃, the Al₂O₃ of high hardness had a strong plough effect on the coating, resulting in a higher friction coefficient of Ni₃Al/Al₂O₃ friction pair. Meanwhile, Al₂O₃ promoted the plastic deformation of the coating, inhibited the fatigue stripping of the material, and made the coating with lower wear rate. At 800 ℃, the high hardness of Al₂O₃ promoted the formation of a lubrication film with high oxide content on the worn surface, so that the Ni₃Al/Al₂O₃ friction pair had low friction coefficient but high wear rate.