Microstructure and Tribological Properties of WC-CeO2/Ni- base Alloy Composite Coatings

摘要:

运用等离子喷涂技术在7005铝合金表面制备了WC和CeO2颗粒协同增强镍基合金复合涂层，研究了该复合涂层的微观结构和摩擦学性能。结果表明：加入CeO2颗粒细化了复合涂层的显微组织，使WC增强颗粒从圆形变为不规则多边形，并降低了其脱碳分解程度。不同PV值摩擦条件下，WC-CeO2/镍基合金复合涂层的摩擦系数和磨损失重均低于WC/镍基合金复合涂层和镍基合金涂层。PV值小于3.36 N·m/s时，复合涂层磨损表面的最大接触应力低于其弹性极限接触应力，主要发生微观切削磨损和疲劳磨损；PV值大于3.36 N·m/s后，磨损表面的最大接触应力超过其弹性极限接触应力，接触温度也急剧上升至648 ℃，磨损表面出现明显的塑性变形和脱落，其磨损机制变为多次塑变磨损、磨粒磨损和粘着磨损，并伴有氧化磨损。

Abstract:

The Ni-base alloy composite coatings synergistically reinforced by WC and CeO2 particles were prepared on the surface of 7005 aluminum alloy by the plasma spray technique. The microstructures and the tribological properties of the composite coatings were researched. The results show that with the addition of CeO2 particles, the microstructure of the composite coating is refined; meanwhile, the WC reinforcing particles change from round to irregular polygon and their decarburization are alleviated. The friction coefficients and the wear losses of the composite coatings are lower than those of the WC/Ni-base alloy composite coatings and the Ni-base alloy coatings at different PV values. When the PV values are smaller than 3.36 N·m/s, the maximum contact stress of the composite coating is lower than its elastic limit contact stress, the wear mechanisms of which are mainly micro-cutting wear and fatigue wear. As the PV values are bigger than 3.36 N·m/s, the maximum contact stress exceeds the elastic limit contact stress of the composite coating and the contact temperature sharply increases to 648 °C, obvious plastic deformation and desquamation traces appear on the worn surface and the wear mechanisms turn into multi-plastic deformation wear, abrasive wear and adhesive wear accompanied with oxidative wear.