利用火焰喷涂技术在中国低活化马氏体(CLAM)钢表面制备了CrFeAlTi涂层,然后通过5 kW横流CO2激光器对该涂层进行多道搭接重熔处理.分别采用体视显微镜、扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机以及基体拉伸试验等分析测试手段对重熔前后涂层显微组织、物相组成、显微硬度、耐磨性能以及界面结合强度进行了研究.试验结果表明:激光重熔处理消除了火焰喷涂CrFeAlTi涂层的层状组织结构、孔洞、裂纹等缺陷,使涂层表面光滑、平整,内部组织致密、均匀,与基体形成了良好的冶金结合界面.火焰喷涂涂层表层物相主要为A12 O3、TiO、CrOo.87、A1FeO3、Cr3 C2和Fe-Cr,激光重熔后涂层表层主要物相为A12O3、TiO2、(A10.948Cro..52)2O3和Cr7C3.激光重熔涂层的平均硬度约为1864.2 HV0.2,比火焰喷涂涂层提高了约1倍.激光重熔涂层在室温干滑动摩擦条件下的耐磨性能明显优于火焰喷涂涂层与基体CLAM钢.激光重熔后涂层与基体的界面结合强度显著提高.
CrFeA1Ti coating was prepared on the China low activation martensitic (CLAM) steel surface by flame spraying,and it was then multi-track overlapping remelted with a 5 kW transverse flow CO2 laser.The microstructure,phases,micro-hardness,wear properties and interfacial bonding strength of the flame sprayed coatings and laser-remelted coatings were investigated by means of stereoscopic microscope,scanning electron microscopy (SEM),X-ray diffraction (XRD),micro-sclerometer,friction wear testing machine and substrate stretching test,respectively.The results show that the defects of the flame sprayed CrFeAlTi coating like layered structure,pores and cracks are eliminated by laser remelting,the surface of the laser remelted coating is smooth,and its microstructure is homogeneous and dense.In addition,a good metallurgical bonding interface is formed between the laser remelted coating and the substrate.The main phases of the flame sprayed coating are A12O3,TiO,CrO0.87,A1FeO3,Cr3C2,and Fe-Cr,while that in the laser remelted coating are A12O3,TiO2,(A10.948 Cr0.032)2O3,and Cr7C3.The average micro-hardness of the laser remelted coating is 1864.2 HV0.2,which is about one time higher than that of the flame sprayed coating.The wear resistance of the laser remelted coating is significantly excellent than that of the flame sprayed coating and the substrate at room temperature and dry sliding wear condition.The bonding strength between the substrate and the coating increases dramatically by laser remelting.
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