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通过6 k W横流CO2激光器在40Cr钢表面激光熔覆了不同成分配比的WC/Co50复合涂层。运用金相光学显微镜(OM),扫描电镜(SEM),能谱仪(EDS)和X射线衍射(XRD)等表征手段分析了涂层结合区形貌、显微组织和物相组成,测试了复合涂层的显微硬度和磨损性能。结果表明,外加的WC颗粒在高能激光束作用下大部分发生溶解,涂层主要由碳化物WC、W2C、(Cr,Fe)7C3和M6C及Fe-Cr固溶体等物相组成。涂层中组织结构比较复杂,出现了树枝状初晶、包状过共晶,枝晶间共晶和硬质相颗粒。WC/Co50熔覆涂层的最大显微硬度位于涂层次表面,其最大平均显微硬度为基材的1.93倍,且随着深度的增加逐渐降低。相同磨损条件下,复合涂层的磨损失重仅为基材的13.3%。
The WC / Co50 composite coating with different compositions was laser cladded on 40Cr steel surface with a 6 kW cross-flow CO2 laser. The morphology, microstructure and phase composition of the bond layer were analyzed by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) Composite coating microhardness and wear properties. The results show that most of the WC particles dissolve under the action of high energy laser beam. The coatings mainly consist of carbide WC, W2C, (Cr, Fe) 7C3 and M6C and Fe-Cr solid solution. The microstructure of the coating is complex, and dendritic primary crystals, inclusions eutectic, interdendritic eutectic and hard phase particles appear. The maximum microhardness of the WC / Co50coated coating is located on the sub-surface of the coating, the maximum average microhardness of the WC / Co50coated coating is 1.93 times that of the substrate, and gradually decreases with the increase of the depth. Under the same wear conditions, the wear loss of the composite coating is only 13.3% of the substrate.