纳米CeO_2/Ni基合金复合材料激光熔覆层组织与耐磨性

Microstructure and wear resistance of laser cladding of nano-CeO_2 /Ni-based alloy composite coating

利用5kWCO2激光器,在Q235低碳钢表面熔覆微米或纳米CeO2/Ni基合金复合材料,制备了涂层。利用光学显微镜、扫描电镜和X射线衍射仪分析比较了熔覆层的组织、磨损形貌及相结构,利用MM-200环-块式滑动磨损机检测了熔覆层的耐磨性。结果表明:熔覆层的主要相为γ-Ni和Cr23C6以及CeNi5,Ni3Si和Ni3B等;加入微米CeO2的Ni基激光熔覆层组织明显细化,并有大量的放射状等轴晶;加入纳米CeO2的Ni基激光熔覆层出现大量更加细小的等轴晶,并且组织致密。含纳米CeO2的Ni基熔覆层与纯Ni基的相比,耐磨性大幅度提高,磨损机理由黏着磨损转变为微动磨损。

Composite coatings made of micron/nano-CeO2/Ni-based alloy were produced by a 5 kW CO2 laser on Q235 low carbon steel. Cross-section of the coatings was examined to analyze their microstructure,morphologies of worn surfaces and phase composition using optical microscope,scanning electron microscope (SEM) and X-ray diffraction instrument (XRD). The wear resistance of cladding was measured with ring-lump sliding wear tester of MM-200 type. The results show that the most phases of cladding are γ-Ni,Cr23C6,CeNi5,Ni3Si and Ni3B. Fine microstructure and radial equaixed dendrite were observed by adding micron-CeO2 to Ni-based alloy,also multitude and finer equaixed dendrite were observed by adding nano-CeO2. The wear resistance of the coating with nano-CeO2 addition was improved more significantly than the coating only made of Ni-based alloy. The wear mechanism was from adhesive wear to fretting wear.