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以H13钢为基体材料,以Co基合金和同粒径范围介孔WC的混合粉末为合金材料,采用半导体激光器在基体表面进行激光熔覆,通过介孔WC的特殊结构,获得均匀的高性能覆层。采用扫描电镜、能谱仪、X-射线衍射分析仪和显微硬度计研究熔覆层的显微组织、元素分布、相组成和显微硬度。利用高温磨损试验机对熔覆层在常温和高温下的磨损性能进行对比分析。结果表明,熔覆层主要由γ-Co以及碳化物硬质相WC、Cr3C2、(Cr,Co)23C6和Cr7C3组成。由于介孔WC颗粒对熔覆层的弥散强化和固溶强化的作用,激光熔覆层显微硬度比基体提高了2倍左右。在600℃高温下,由于碳化物硬质相的作用,熔覆层的高温耐磨性相比H13基体提高了3倍左右,熔覆层的高温磨损形式主要以氧化磨损为主。由于温度的升高,熔覆层表面形成氧化膜,从而对熔覆层进行有效保护,因此熔覆层的耐磨性随着温度的增加而提高。
Using H13 steel as base material and mixed powder of Co-based alloy and mesoporous WC with the same grain size as the alloy material, laser cladding is performed on the surface of the substrate by a semiconductor laser to obtain uniform high-performance through the special structure of the mesoporous WC Cladding. The microstructure, elemental distribution, phase composition and microhardness of the cladding were studied by SEM, EDS, X-ray diffraction and microhardness tester. The wear performance of cladding layer at normal temperature and high temperature was analyzed by high temperature wear tester. The results show that the coating mainly consists of γ-Co and carbide hard phases WC, Cr3C2, (Cr, Co) 23C6 and Cr7C3. Due to the effect of the WC particles on the dispersion strengthening and solid solution strengthening of the cladding layer, the microhardness of the laser cladding layer is about 2 times higher than that of the matrix. At high temperature of 600 ℃, the high temperature wear resistance of the cladding layer is about 3 times higher than that of the H13 matrix due to the carbide hard phase, and the wear form of the cladding layer is mainly oxidative wear. Due to the increase of temperature, an oxide film is formed on the surface of the cladding layer and the cladding layer is effectively protected. Therefore, the wear resistance of the cladding layer increases with the increase of the temperature.