提高Ti6Al4V耐磨性的热氧化工艺

Wear-resistance improvement of Ti6Al4V surface by thermal oxidation treatment

针对钛合金具有耐磨性差等缺点,提出了钛合金热氧化处理工艺。选择Ti6Al4V合金在850℃下进行氧化/真空扩散处理,同时作为对比进行了长时间的直接氧化处理。研究结果表明:氧化时间和真空扩散是影响氧化层性质的关键因素,氧化时间达90min时氧化层的致密性遭到破坏,氧化780min时氧化层自动剥落;经过真空扩散处理可促进氧向基体内扩散,从而使氧化层中的TiO2转变为TiO,同时氧渗入基体中强化了表面层,二者共同作用改善了钛合金表面的摩擦性能,提高了钛合金的耐磨性;试样在850℃氧化45min然后真空扩散12h后,其强化层达到约200μm,且耐磨能力最强。

In order to improve the wear-resistance of titanium alloys surfaces, a thermal oxidation process was investigated. The Ti6Al4V alloy was oxidized at 850 ℃ for different time in air, followed by vacuum diffusion at 850 ℃ for 12 h. A sample was only oxidized in air as compared with the samples mentioned above. The results show that the oxidation time in air is one of critical factors that affect the quality of the oxidation layer, and the diffusion treatment in vacuum is the essence of the thermal oxidation process. The oxidation layer is not adherent when oxidating for 90 min, and it scales off when oxidating for 780 min. After diffusion in vacuum, TiO_2 of the oxidation layer changed into TiO, and oxygen penetrated into the substrate and strengthened the surface. Thus the tribological property of Ti6Al4V is improved. The thickness of strengthened layer of the sample is about 200 μm, which is obtained by oxidizing at 850 ℃ for 45 min in air and vacuum diffusion at 850 ℃ for 12 h, and the sample shows the best wear-resistance.