激光熔覆原位生成B4C颗粒增强镍基复合涂层的研究

采用自动送粉工艺,在A3钢表面制备出原位生成B4C颗粒增强的镍基激光熔覆层.使用扫描电镜(SEM),电子能谱(EDS)和X射线衍射仪(XRD)对熔覆层的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,原位生长B4C颗粒增强的Ni基复合涂层与基材呈现良好的冶金结合.熔覆层的底部组织为先共晶析出的Cr,Fe的碳化物树枝相分布在γ(Ni Fe)基体中,而中上部组织为先共晶析出的树枝晶和包含原位生成B4C的白色颗粒相分布在共晶基体中.熔覆层具有极高的硬度(平均HV0.31400),耐磨性是纯Ni60涂层的2倍.硬度和耐磨性的提高归因于涂层中大量的包含原位生长B4C颗粒相的生成,并均匀分布于涂层的共晶基体中.

Research on In-Situ Synthesis of B4C Particulate Reinforced Ni-Based Composite Coatings by Laser Cladding

B_4C particulate reinforced Ni-based composite coating has been successfully in situ synthesized by laser cladding on steel A3 substrate by powder feeding.The microstructure observation,component and phases analysis of the coatings were performed by scanning electron microscope(SEM),energy-dispersive spectrometer(EDS) and X-ray diffractometer(XRD).The micro-hardness test in the cross-section and tribotesting onto the surface of the laser cladding were accomplished also.The results indicate that the coating epitaxial growing from the substrate with excellent bonding between the coating and substrate is ensured by the strong metallurgical interface.Both particle in which in-situ synthesized B_4C embedded and the dendritic consisted of Cr, Fe carbide are homogenously dispread in the eutectic matrix other than only the dendritic where near the bonding interface.The in situ synthesized B_4C particulate reinforced Ni-based composite coating gives very high hardness of HV_(0.3)1400,and has excellent wear resistance which is two times as high as that of Ni60 coatings.The improvement in hardness and wear resistance of the layer is due to the in-situ synthesis of B_4C and its homogenous distribution in the cladding layer.