Microstructure and Wear Resistance of Laser Clad Cobalt- based Composite Coating on TA15 Surface

摘要:

利用横流CO2激光器在TA15钛合金表面通过优化的激光熔覆工艺制备出原位自生的多种颗粒增强钴基复合涂层，以增强表面的耐磨性和硬度。利用X射线衍射(XRD)、金相、扫描电镜(SEM)、硬度测试机和磨损试验机等方法对熔覆层进行分析。结果表明，熔覆层的显微结构主要由γ-Co、α-Ti固溶体和弥散分布的原位自生TiB2,、Cr5Si3,、TiC、WB、SiC、Co3Ti、NiC颗粒组成，这些多种颗粒增强相弥散分布在细小的树枝晶组织之间。熔覆层的显微硬度比基体提高很多，HV达到10000 MPa左右，约为基体硬度的3倍。与钛合金相比，熔覆层的耐磨性也有显著提高，其磨损率约为钛合金的1/12。熔覆层的磨损机理具有粘着磨损和磨粒磨损的混合特征

Abstract:

The cobalt-based composite coating reinforced with in-situ synthesized multiple particles was fabricated on TA15 titanium alloy surface by transverse flow CO2 laser adopting the optimizing laser cladding process parameters to improve wear resistance and hardness in surface. X-ray diffraction (XRD), metallurgical microscope, scanning electron microscope (SEM), hardness tester and wear testing machine were used to analyze the coating. The results show that the microstructures of the coating are mainly composed of γ-Co, α-Ti solid solution and in-situ synthesized TiB2, Cr5Si3, TiC, WB, SiC, Co3Ti and NiC particles. And these multiple granular reinforced phases are dispersively distributed among the fine dendritic structures in the cladding layer. The microhardness of the cladding layer compared with that of the substrate, has been improved a lot, HV reaching about 10000 MPa which is around three times higher than that of the substrate. Compared to titanium alloy, the wear resistance of the cladding layer has been distinctly improved, and the wear rate of the cladding layer is about 1/12 of the titanium alloy. The wear mechanism of the cladding layer is a mixed type of adhesion and abrasion