利用6 kW横流CO2激光器制备了Co50熔覆层和不同成分配比的Co/TiC复合涂层来改善H13模具钢表面的热磨损性能。借助X射线衍射(XRD)、扫描电子显微镜(SEM)、显微硬度计和高温摩擦磨损试验机分析了涂层的结合特征、物相组成和不同温度下的摩擦磨损性能。结果表明, 当预置层粉末TiC含量(重量百分比)小于等于20%时, 熔覆层与H13钢基材呈良好的冶金结合; 随着TiC含量的增加, Co/TiC复合涂层截面平均显微硬度呈上升趋势, 但涂层中基体相种类减少: Co＋10%TiC涂层由TiCo3、Cr2Ni3和Cr-Ni-Fe-C组成, Co＋20%TiC涂层由Cr2Ni3和γ-Co组成, Co＋30%TiC涂层为γ-Co固溶体。Co＋20%TiC涂层的高温耐磨性比Co50涂层显著提高, 摩擦系数平稳; 700 ℃时复合涂层的磨损机制主要为氧化磨损和疲劳磨损。结果显示Co＋20%TiC涂层具有良好的综合性能。

Co50 alloy coating and Co50 composite coatings doped with different mass fractiones of TiC were prepared by a 6 kW transverse-flow CO2 laser to improve the wear resistance of H13 die steel. The bonding characteristics, phase composition and wear behaviors of the coatings were investigated by X-ray diffractometry(XRD), Scanning Electron Microscopy(SEM) and high-temperature wear tester. The experimental results indicate that Co/TiC composite coatings with the content of TiC less than 20% (weight percentage) show good metallurgical bonding characteristics with the substrate surface. In addition, the micro-hardness of TiC/Co based coatings increases with the TiC content, but matrix phase composition of the composite coatings tends to be simple: Co+10%TiC coating consists of TiCo3, Cr2Ni3 and Cr-Ni-Fe-C phases, while Co+20%TiC coating is Cr2Ni3 and γ-Co, and Co+30%TiC coating mainly is composed of γ-Co solid solution. Co+20%TiC coating shows better wear behavior than Co50 coating, as well as has a more stable friction coefficient. Moreover, the high-temperature wear is mainly caused by oxidation wear and fatigue wear.These results demonstrate that Co+20%TiC composite coating has good comprehensive properties.