中文摘要：

为了改善Ti6Al4V合金的摩擦学和高温抗氧化性能,预置Ni Cr/Cr3C2-Al-Si复合粉末,采用激光熔覆技术在钛合金表面制备复合涂层。表征了涂层的显微组织结构,测试了涂层的摩擦学和高温氧化性能,并分析了相关机理。结果表明：涂层由Ti C、Ti5Si3和Cr3Si增强相及γ-Ni/Al8Cr5基体组成,平均显微硬度为750 HV0.5,约为Ti6Al4V（360 HV0.5）合金的2倍。室温（25℃）下,由于涂层的高硬度可有效抵抗塑性变形,涂层表现出较好的耐磨性能;高温（600℃）下,钛合金表面生成氧化膜,呈现自润滑效果,而涂层表面产生裂纹,耐磨性能轻微降低。恒温（800℃）氧化32 h后,钛合金表面发生严重氧化腐蚀,而涂层表面生成致密的Al2O3、Ni O和Cr2O3混合氧化物,有效阻止了氧原子的扩散,高温抗氧化性能约为钛合金基体的8.4倍。

英文摘要：

In order to simultaneously improve the high-temperature wear and oxidation resistance of Ti6Al4 V alloy, the composite coatings are prepared on the surface of Ti6Al4 V alloy by laser cladding with the precursor mixed Ni Cr/Cr3C2- Al- Si powder. Microstructure, wear and high temperature oxidation resistance of laser cladding coatings are analyzed. The results show that Ti C, Ti5Si3 and Cr3Si particulate reinforced γ-Ni/Al8Cr5 matrix composite coatings are formed. The average micro-hardness of the composite coating is 750 HV0.5, and is almost twice as much as that of Ti6Al4 V alloy. At room temperature, compared to Ti6Al4 V alloy, the composite coating exhibits excellent tribological property due to its high hardness. While at high temperature of 600 ℃, the formation of protective transferred layers between the sliding surface of Ti6Al4 V alloy and the ceramic couple can play a positive self-lubrication role. Compared with the Ti6Al4 V alloy, the wear resistance of the composite coating has slight decrease because of the formation of micro-cracks on the worn surface at high temperature. After isothermal oxidation tests at 800 ℃ for 32 h, the Ti6Al4 V alloy is oxidized quickly because of the high affinity of Ti towards O and the non- protective oxide scales of Ti O2. The composite coating can form continuous Al2O3, Ni O and Cr2O3 oxide scales on the surface, which is more protective than Ti O2. The high-temperature oxidation resistance of the laser cladding composite coating is approximately 8.4times higher than that of the Ti6Al4 V alloy.