激光原位制备硼化钛与镍钛合金的摩擦磨损性能

为了制备出可对比的两类复合涂层,采用TiB2和Ni+TiB2分别作为熔覆材料,在钛合金表面通过激光原位熔覆制备复合涂层。采用XRD、SEM、EPMA与摩擦磨损仪等实验手段,对合成的钛基复合涂层进行研究。结果表明:采用TiB2为熔覆材料时,可获得TiB2颗粒与TiB短纤维增强钛基复合涂层。采用Ni+TiB2为熔覆材料时,可生成NiTi合金填充在TiB2颗粒与TiB短纤维周围,但TiB2颗粒尺寸和TiB短纤维长度都得以减小。通过微动磨损测试,发现引入NiTi合金和TiB2颗粒及TiB短纤维复合强化,无法有效抵抗微动磨损性能。这主要与摩擦接触区的温度超过NiT超弹性变形的温度区间,且NiTi合金无法使裂纹扩展曲折及硬度低相关。最后,探讨了该复合涂层在抗微动磨损与干滑动磨损过程中的差异性。

Friction and wear properties of laser in situ synthesized titanium diboride and NiTi alloy

In order to prepare two kinds of composite coatings for comparison,TiB2 and Ni+TiB2 were,respectively,used as cladding materials,and the composite coatings were prepared by laser in-situ cladding technique on the surface of titanium alloy.The synthesized titanium-based composite coatings were studied by XRD,SEM,EPMA and friction and wear instruments.The results show that TiB2 particle and TiB short fiber reinforced titanium-based composite coating can be obtained when TiB2 is used as the cladding material.When Ni+TiB2 is used as the cladding material,the NiTi alloy can be formed to be filled around the TiB2 particles and the TiB short fibers,but the size of the TiB2 particles and the length of the TiB short fibers are all reduced.Through the fretting wear test,it is found that the composite reinforcement of NiTi alloy and TiB2 particles and TiB short fiber can not effectively resist the fretting wear performance.There are three reasons for this:the temperature of the friction contact zone exceeds the temperature of the NiTi superelastic deformation,the crack propagation cannot be deflected by the introduction of NiTi,the hardness of the NiTi alloy is low.Finally,the difference between the anti-friction wear and dry sliding wear of the composite coating was discussed.