TC4钛合金表面激光熔覆复合涂层的组织和耐磨性

Microstructure and wear resistance of laser clad composite coating on TC4 titanium alloy surface

采用5kW横流CO2激光器,在TC4钛合金表面熔覆TiC、TiB2与Ni的混合粉末,制备了无气孔、无裂纹、组织均匀致密的复合涂层。用SEM、EDS、XRD、显微硬度计以及立式万能摩擦磨损试验机分析了激光熔覆层的显微组织、成分和物相,测试了激光熔覆层横截面显微硬度,以及覆层耐磨性能。结果表明,激光熔覆复合涂层与基体呈冶金结合;熔覆层组织从表层到结合区呈现出由棒状、块状向树枝状、颗粒状转变的趋势,且主要由Ti、TiC、TiB、Ti2Ni、TiNi等相组成;熔覆层显微硬度最高可达863HV0.2,为基体的2.5倍;熔覆层耐磨性能较TC4钛合金明显提高。

The pore-free and cracks-free composite coating was in-situ synthesized on the surface of TC 4 titanium alloy by laser cladding with 5 kW continuous wave CO2 laser.Microstructure, composition and phase distributions of the composite coating were investigated by means of SEM, EDS, XRD, and microhardness , and friction wear properties were measured by microhardness tester and wear test machine respectively .The results show that the composite coating is well metallurgical bonded with TC 4 titanium substrate .The microstructure morphology of clad layer changes from rod and block shape at the surface zone to dendrite and particles at bonding zone .The coating is mainly composed of Ti , TiC, TiB, Ti2 Ni and TiNi.The maximum microhardness of the coating reaches 863 HV0.2 which is 2.5 times of that of TC4 substrate , and the wear resistance of TC 4 titanium alloy is significantly improved .