ISSN   1004-0595

CN  62-1224/O4

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Ti6Al4V合金表面激光熔覆复合涂层的高温摩擦学性能研究

High-Temperature Tribological Properties of Laser Clad Composite Coatings on Ti6Al4V Alloy

  • 摘要: 为了改善Ti6Al4V合金的摩擦学性能, 采用预置NiCrBSiFe复合粉末激光熔覆制备高温耐磨复合涂层, 分析了涂层的显微组织, 测试了其显微硬度、室温(25 ℃)及高温(600 ℃)磨损性能, 并分析了其机理. 结果表明: 复合涂层与钛合金基体为冶金结合, 以γ-(Ni, Cr, Fe)固溶体为基体, 原位生成的TiC、TiB2和CrB增强相均匀分布于涂层中,涂层的平均硬度为HV0.5950, 约为钛合金基体(HV0.5360)的3倍. 室温下, 由于涂层具有很高硬度, 改善了钛合金表面严重的黏着磨损, 涂层表现出优异的耐磨性; 高温下, 钛合金表面生成氧化膜表现出固体润滑效果, 摩擦系数和磨损量均下降, 而涂层中基体相硬度下降, 磨损表面出现犁沟和破碎磨粒, 摩擦系数和磨损率相比室温略有上升, 但相比钛合金仍表现出较好的高温耐磨性.

     

    Abstract: Wear resistant composite coatings were deposited on Ti6Al4V alloy substrate with the preplaced NiCrBSiFe alloy powders by laser cladding. Microstructure, micro-hardness, room-temperature (25 ℃) and high-temperature (600 ℃) wear resistance of the laser clad composite coatings were determined. The results show that the composite coating were composed of γ-(Ni, Cr, Fe) solid solution matrix and TiC, TiB2 and CrB reinforced particulates, which were uniformly distributed in the coating. The metallurgical bonding between cladding coating and substrate was observed. The average micro-hardness of the composite coating was HV0.5950, which was almost three times higher than that of the substrate (HV0.5360). At room-temperature, the composite coating possessed excellent tribological properties due to its relatively high hardness. At high-temperature, the friction coefficient and wear rate of Ti6Al4V alloy all reduced because of the formation of TiO2 oxide scales and the solid lubrication effect. Due to the reduction of micro-hardness of the composite coating, some wear debris and plowing grooves occurred on the worn surfaces of the composite coating. The friction coefficient and wear rate of the composite coating increased slightly. Compared with the Ti6Al4V alloy, the laser clad composite coating exhibited better wear-resisting capability at room temperatures and 600 ℃.

     

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