CeO_(2)对WC/Ni复合熔覆层微观组织与性能的影响

Effect of CeO_(2)on Microstructure and Properties of WC/Ni Composite Cladding Coating

本工作采用真空熔覆技术制备了不同CeO_(2)含量的WC/Ni复合熔覆层,通过SEM、XRD、EDS及显微硬度计对复合熔覆层的微观组织、成分及硬度分布等进行系统分析。结果显示:与基体呈冶金结合的复合熔覆层组织致密,复合熔覆层由厚度2~3 mm且具有网状结构特征的复合层区与约300μm的过渡层区组成,根据熔合程度过渡区又分为冶金熔合区、扩散熔合区及扩散区;随着CeO_(2)含量的增加,复合熔覆层的晶粒逐渐细化、熔合质量提高,特别是过渡熔合区出现鱼骨状的析出相;复合区的网孔部位主要组成相为γ-(Ni,Fe)固溶体、FeNi_(3)、Cr_(7)C_(3)、Cr_(23)C_(6)、Ni_(3)Si和NiB,网线区主要组成相为WC、WC_(2)、γ-(Ni,Fe)固溶体、共晶组织等;复合熔覆层的显微硬度由表面至基体逐渐降低,且随着CeO_(2)含量的增加硬度逐渐升高,CeO_(2)含量为1.5%时,达到最大值,其平均显微硬度比基体提高5~6倍。

The vacuum cladding technology was used to prepare WC/Ni composite cladding coating modified with different CeO_(2)content.The microstructure,composition and microhardness of the WC/Ni composite coating were systematically analyzed by SEM,XRD,EDS and microhardness tester.The results showed that the microstructure of composite cladding coating was dense and the interface between composite coa-ting and 45#steel substrate was metallurgical bonding.The composite cladding coating included the composite layer with network structure cha-racteristics of 2—3 mm and the transition layer of about 300μm thickness.With the increasing of CeO_(2)content,the grain size of the composite cladding coating was gradually refined and its fusion quality improved,especially the fishbone precipitated phase appeared in the metallurgical fusion zone of transition layer.The main phases of the mesh hole region in the composite layer wereγ-(Ni,Fe)solid solution,FeNi_(3),Cr_(7)C_(3),Cr_(23)C_(6),Ni_(3)Si and NiB,while the main phases of the mesh line region were WC,WC_(2),solid solution and eutectic.The microhardness of composite cladding coating gradually decreased from the composite coating surface to 45#steel substrate,and its average microhardness gradually increased with the increasing of CeO_(2)content.The maximum value was reached when the CeO_(2)content was 1.5%,and the average microhardness was 5—6 times higher than that of the substrate.