等离子喷涂NiAl-MoO3/BaO复合涂层的高温摩擦学性能及润滑机理研究

Tribological Properties and Lubrication Mechanisms of Plasma Sprayed NiAl-MoO3/BaO Composite Coatings at High Temperature

目的根据氧化物润滑离子势和阳离子极化率判据,研究MoO3/BaO复合对等离子喷涂NiAl基复合涂层的高温摩擦学性能影响,并阐明复合涂层的高温润滑机理。方法采用等离子喷涂技术(APS)制备MoO3/BaO(1∶1)质量分数分别为20%、30%、40%的复合涂层。采用显微硬度计、万能材料试验机、摩擦磨损试验机等测试复合涂层的硬度、结合强度、摩擦学性能。通过扫描电镜(SEM/EDS)、X射线衍射仪(XRD)、激光拉曼散射仪(Raman)和透射电子显微镜(TEM)分析涂层的微观组织结构、磨损表面形貌、物相结构等。结果选用互作用参数较低和离子势差较大的MoO3/BaO作为复配润滑剂制备的NiAl-MoO3/BaO复合涂层有效改善了NiAl涂层的高温摩擦学性能,特别是NiAl-30%MoO3/BaO(1∶1)的复合涂层在800℃具有较低的摩擦系数(0.15)和磨损率(9.31×10^-5mm^3/(N·m))。结论复合涂层在600℃以上具有良好的减摩性能,高温促进了磨损表面形成新的三元高温润滑相BaMoO4、NiMoO4,并与MoO3和NiO起到协同润滑作用,显著提升了复合涂层的高温摩擦磨损性能,同时摩擦对偶表面形成的复合氧化物润滑转移膜,降低了涂层的磨损率。

The work aims to study the effect of MoO3/BaO composite on the tribological properties of plasma sprayed NiAl matrix composite coating at high temperature according to the oxide ionic potential and cation polarizability criterion,and clarify the high temperature lubrication mechanism of the composite coating.The composite coatings with 20,30 and 40wt%MoO3/BaO(1∶1)were fabricated by atmospheric plasma spraying technology.The micro-hardness,bonding strength and tribological properties of composite coatings were tested by micro-hardness,universal material testing machine and friction and wear testing machine,respectively.Meanwhile,the micro-structure,phase composition,elemental distribution and morphology of the worn surface of composites coatings were in-depth analyzed by the scanning election microscopy(SEM/EDS),X-ray diffraction(XRD),micro-Raman and transmission electron microscopy(TEM).The NiAl-MoO3/BaO composite coating prepared by MoO3/BaO with lower interaction parameters and large ionic potential difference as composite lubricant effectively improved the tribological properties of NiAl coating at high temperature.Especially,the NiAl-30wt%MoO3/BaO(1∶1)composite coating had a low friction coefficient of 0.15 and a wear rate of 9.31×10^-5 mm^3/(N·m)at 800℃.The composite coating has good anti-friction performance at the temperature above 600℃.High temperature promotes the formation of new ternary high temperature lubricating phases BaMoO4 and NiMoO4 on the worn surface,and plays a synergistic lubrication effect on MoO3 and NiO,thus improving the friction and wear resistance of the composite coating at high temperature.At the same time,the formation of a composite oxide lubricating transfer film on the friction dual surface further reduces the wear rate of the coating.