中文摘要：

探讨了激光熔覆TiC4复合陶瓷涂层微观结构特征,研究了氧化铈对涂层显微组织、显微硬度及摩擦学性能的影响.在45#钢基体上制作了Ni、Cr、TiC4复合陶瓷涂层及氧化铈改性的复合涂层,用X射线衍射仪（XRD）、分析型扫描电镜（ASEM）、显微硬度计及摩擦磨损试验机对涂层组成、显微组织、显微硬度及摩擦学性能进行了分析.结果表明：利用激光熔覆方法制作的TiC4陶瓷层具有典型的包覆相和硬质点相结构,加入适量的氧化铈能有效防止TiC4结晶过程中颗粒桥接,阻止TiC4结晶成枝状结构,细化了TiC4颗粒,同时也使其分布更加离散.当添加氧化铈的质量分数为0.50%～3.0%时,TiC4颗粒离散效果最好,此时涂层显微硬度分布均匀,较不添加氧化铈涂层相比,显微硬度提高了10%左右,当添加氧化铈的质量分数超过4.0%,TiC4颗粒发生桥接,成枝状结构,且出现聚集,硬度分布离散度加大.磨损试验结果表明氧化铈能改善涂层的干摩擦特性,有效防止涂层片层状脱落,但对涂层耐磨性没有明显的改进,涂层呈现黏着磨损特征.

英文摘要：

TiC4 composite ceramic coatings with different CeO2 contents were deposited on 45# carbon steel substrate by laser-cladding.The cladding coatings were examined and tested for microstructural features,chemical compositions,phase structure,microhardness by scanning electron microscope（SEM）,X-ray diffraction（XRD）analysis and micro-hardness tester separately.TiC4 particles phase and surrounding TiC4 particles rim phase was found by SEM,XRD.Experimental results showed the addition of CeO2 improved the dispersion of TiC4 grain and prevented the TiC4 particle from bridging.At 2.0 wt.% CeO2,the TiC4 grains shows best dispersion,and the micro-hardness of the coating reached 1100 MPa.With excessive CeO2,the TiC4 grains became bridging,the pattern of particles submit long strip,and the cladding layer＇s micro-hardness decreased slightly.Dry friction tests showed the addition of CeO2 improved the tribological properties.The wear mechanism of cladding coating without dopping was servere adhension and scuffing,while that of the CeO2 dopped coating was dominated by mild abrasive wear.Dopping CeO2 had no obvious improvement on the wear resistance of the coating.