The pore-free and cracks-free TiC/TiB composite coating is in-situ synthesized on TC4 titanium alloy by laser cladding with 5 kW continuous wave CO2 laser. Microstructure morphology,composition and phase distributions of the composite coating are investigated by scan electron microscopy ( SEM) , energy-dispersive X-ray spectroscopy (EDX) ,X-ray diffraction(XRD) .respectively. Micro hardness is measured by HXD-1000B microhardness tester. The results show that the TiC/TiB composite coating is well metallurgical bonded with TC4 titanium substrate. The micro-structure morphology of the cladding layer changes from cross petals shape TiC at the surface zone to TiC particles at bonding zone. Between the cross petals shape and particles morphology is filled with dense fibrous tissue TiB. Fibrous tissue from the surface to bonding zone gradually increases. Microhardness of the coating is reached 1240HV0.2 that is 3.5 times of TC4 substrate.%采用5 kW横流CO2激光器,在TC4钛合金表面熔覆TiC与TiB2混合粉末,制备出了组织细密、无裂纹与气孔的TiC/TiB复合陶瓷涂层.采用扫描电镜(SEM)、能量散射X谱仪(EDX)、X射线衍射仪(XRD)以及HXD-1000B显微硬度计,分析了熔覆层的显微组织形貌、成分与物相结构,测试了激光熔覆层的显微硬度.结果表明,激光熔覆原位制备的TiC/TiB复合涂层与基体呈冶金结合,熔覆层组织呈现出由表层十字形花瓣状TiC组织到结合区致密小颗粒TiC组织分布变化的特点.同时,熔层中有大量的纤维状TiB组织填充在十字形花瓣状组织与颗粒状组织之间,且纤维组织从熔覆层表层到结合区逐渐增加.熔覆层的显微硬度值最高可达1240 HV0.2,为基体的3.5倍.
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