TiAl合金激光熔覆金属硅化物复合材料涂层耐磨性和高温氧化性能研究

利用预涂NiCrSi复合粉末时TiAl合金进行激光熔覆处理，分析了原始TiAl合金和激光熔覆复合材料涂层的耐磨性能和高温抗氧化性能，讨论了磨损和高温抗氧化机理及其与预涂合金粉末成分的关系。结果表明，涂层的滑动磨损和耐磨性能有提高，但当耐磨相体积分数过高时，由于涂层脆性增大，其耐磨性呈下降趋势；涂层在1000℃恒温氧化条件下均具有较好的抗氧化性能，氧化层结构较连续致密，主要由α-Al2O3，TiO2和SiO2组成。预涂NiCr-40％Si混合合金粉末的激光熔覆复合材料涂层具有更好的耐磨性和高温抗氧化性能。

Study on Wear and High-Temperature Oxidation Properties of Laser Clad Metallic Silicide Composite Coatings on TiAl Intermetallic Alloy

γ-NiCrAl/Ti5Si3/TiSi composite coatings were fabricated on γ-TiAl intermetallic alloy by laser cladding with NiCr-Si precursor mixed powders. The room temperature wear resistance of the laser clad composite coatings was evaluated under dry sliding wear test conditions and the elevated-temperature isothermal oxidation-resistance was conducted at 1000 ℃ for 50 h in air. The wear and oxidation mechanisms were discussed based on the experimental results. The results show that the sliding wear resistance of the laser clad composite coating increases. However, too high a volume fraction of the reinforcement phases leads to the decrease of wear resistance due to the brittleness of the composite coating. The isothermal elevated-temperature oxidation resistance of all the laser clad composite coatings is enhanced significantly and the relatively continuous oxide scales consist of α-Al2O3, TiO2 and SiO2.