激光制备原位自生NbC-VC颗粒增强镍基熔覆层

In situ synthesized NbC-VC particulate reinforced Ni-based composite coating produced by laser cladding

采用预涂粉末激光熔覆技术,在A3钢表面制备出原位自生NbC-VC颗粒增强的镍基复合涂层。使用扫描电镜、电子能谱、和X射线衍射仪对熔覆层的显微组织和物相构成进行了分析,并对熔覆层进行了硬度、摩擦性能测试。结果表明,原位生成NbC-VC颗粒增强镍基复合涂层与基材呈现良好的冶金结合,熔覆层底部组织为定向生长的γ(NiFe)树枝晶,熔覆层中上部组织为先共晶析出的NbC-VC颗粒和Cr3C2条状相均匀分布于γ(NiFe)基体中。由于大量NbC-VC颗粒相的形成及其弥散分布,熔覆层具有高的硬度(平均硬度HV0.31150)和良好的耐磨性,与纯Ni60熔覆层相比,其磨损失重为纯Ni60熔覆层的1/3。

The in-situ NbC-VC reinforced Ni-based composite coating has been successfully synthesized by laser cladding on Steel A3 by prior to pasting.The microstructural and phase analyses were performed by a scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffractometer.The microhardness and wear resistance were investigated using a microhardness tester,wear and tear testing machinery.The results show that the coating is bonded metallurgically to the substrate.The microstructure in the bottom of coating consists mainly of oriented dendrites of γ（NiFe）,and the microstructure in the center and upper zone consists of both NbC-VC particle and Cr3C2 acicular phase dispersed uniformly in the matrix of γ（NiFe）.Because of in situ synthesis of lots of NbC-VC particle,the ocmposite coating gives a high average hardness of HV0.31150 and better wear resistance,the wear mass loss of this coating is just one third that of the pure Ni60 coating.