等离子喷涂Al_2O_3-TiO_2陶瓷涂层的显微组织及摩擦学性能

以Al_2O_3-TiO_2(x=0%,3%,13%,20%,40%,质量分数)复合陶瓷粉末为原料,采用等离子喷涂工艺在316L不锈钢基体表面制备5种陶瓷涂层。利用扫描电镜(SEM)、能谱仪(EDS)和X线衍射仪(XRD)、荧光金相显微镜分析粉末和涂层形貌、微观结构、物相组成及涂层孔隙率;利用显微硬度计及摩擦磨损试验机测试涂层力学及摩擦学性能,观察试样磨损形貌,分析磨损机理。结果表明:涂层呈典型的等离子喷涂层状堆积特征,涂层与基体结合良好。随TiO_2含量增加,涂层主相由γ-Al_2O_3向Al_2TiO_5相过渡,涂层韧性升高,硬度和孔隙率降低。在大气环境下,低TiO_2含量的涂层(Al_2O_3、AT3)发生应力疲劳磨损,高TiO_2含量的涂层(AT13、AT20和AT40)发生应变疲劳磨损;而在水环境下,5种涂层均发生应力疲劳磨损。

Microstructure and tribological properties of Al2O3-TiO2 coating deposited by plasma spraying

The ceramic coatings were prepared on 316L stainless steel by atmospheric plasma spraying with Al2O3-xTiO2(x=0%, 3%, 13%, 20%, 40%, mass fraction) composite ceramic powders. The surface morphology, microstructures, phase compositions and porosity of the powders and coatings were characterized by SEM, EDS, XRD and optical microscopy. The hardness and tribological properties were tested by Vickers’ hardness tester and wear tester. The worn surface were observed and the wear mechanism was also discussed. The results show that the composite ceramic coating presents typical lamellar structure, and the as-sprayed coatings maintain good mechanical bonding to the substrate. With increasing TiO2 content, the main phase transforms from the metastable phase ofγ- Al2O3 to Al2TiO5, while the toughness increases, the hardness and porosity decrease. Under atmosphere condition, the low levels of TiO2 content coatings (Al2O3, AT3) show fatigue stress wear. The high levels of TiO2 content coatings (AT13, AT20 and AT40) show fatigue strain wear. Under water condition, five coatings occur fatigue stress wear.