钛合金表面激光熔覆TiC/Ti-Ti_2 Co涂层耐磨性

Wear resistance of laser clad TiC/Ti-Ti_2Co coating on titanium alloy

为了提高钛合金的耐磨性能,以Co基合金粉末、钛粉和活性碳为原料,利用激光熔覆技术在TC4钛合金基材表面制得以原位自生TiC为增强相的耐磨涂层,用光学显微镜、扫描电子显微镜、X射线衍射仪和能谱仪等分析了涂层的显微组织、相组成及成分,在室温干滑动磨损条件下测试了涂层的室温耐磨性能。结果表明,原位生成的TiC增强相主要以发达树枝晶形态均匀分布于β-Ti,Ti_2Co共晶组织基体中;β-Ti为不规则枝晶或胞状晶,而Ti_2Co主要呈不规则块状分布,少量-Ti_2Co以片层状形成于β-Ti枝晶臂间;涂层与基材呈良好的冶金结合,显微硬度约HV600～HV700,具有优异的室温干滑动磨损性能,其中,硬质TiC相起主要抗磨作用。这一结果对提高钛合金的耐磨性能是有帮助的。

In order to improve the tribological properties of titanium alloy, a wear resistant coating with a microstructure consisting of in situ TiC primary dendrites and Ti-Ti2Co matrix was fabricated on a substrate of titanium alloy TCA by means of laser cladding using Co-based alloy powders, activated carbon and titanium powders as the precursor materials. The microstructure and composition of the intermetallic composite coating was studied by means of optical microscope, scanning electron microscope, X-ray diffraction, energy dispersive spectrometer. The wear resistance of the coating was tested under dry sliding wear condition at room temperature. It is revealed that the laser clad composite coating has a rapidly solidified homogeneous microstructure and is metallurgically bonded to the substrate. The developed in situ TiC primary dendrites dispersed in the β-Ti-Ti2Co matrix of the coating as reinforcements. The β-Ti phase shows irregular crystal or cell dendrites. And most of the Ti2Co phase distributes over the matrix as irregular block crystal, with some lamellar Ti2Co formed in the inter-dendrite arms of the β-Ti phase. It is found that the microhardness of the coating is in the range of HV600 - HV700. The laser clad TiC/Ti- Ti2Co coating, in which the TiC phase plays a main role in enhancement, has excellent wear resistance under dry sliding wear test conditions. The results show that the coating is helpful to improve wear resistance of titanium alloy.