Ni-Co/WC-Graphite复合熔覆层的组织与三点弯曲行为  

Microstructure and bending behavior of Ni-Co/WC-Graphite composite coatings fabricated through vacuum cladding

作　　者：宋文明[1,2] 杨贵荣[1] 王旭升[1] 王富强[1] 李健[3] 马颖[1] 

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]甘肃蓝科高新石化装备股份有限公司,兰州730070 [3]武汉材料保护研究所,武汉430030

出　　处：《复合材料学报》2017年第7期1552-1560,共9页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金(51205178);甘肃省自然科学基金(14RJYA308)

摘　　要：采用真空熔覆技术制备了Ni-Co/WC-Graphite(G)复合熔覆层,采用SEM、XRD等分析了微观组织及相组成,利用三点弯曲研究了复合熔覆层的弯曲行为,并分析了断口形貌特征、微区元素分析与断裂机制。结果表明:整个Ni-Co/WC-G熔覆层包括复合层区、过渡层区、扩散冶金熔合带以及热影响扩散区,复合层区呈现三维织构组织特征,主要组成相有Cr_7C_3、Cr_(23)C_6、Ni_3Si、CrB、WC、C和γ-Ni-Co固溶体,扩散影响区主要组织为珠光体,扩散冶金熔合带及过渡层主要组成相为镍钴基合金固溶体及金属间化合物;具有复合熔覆层试样的三点弯曲载荷-位移曲线初始呈线性变化,而后曲线斜率逐渐减小,在达到载荷峰值时Ni-Co/WC-G复合熔覆层在承受压应力时溃裂,而在承受拉应力时断裂,由于过渡层、扩散冶金带以及热影响扩散区的存在,使载荷在熔覆层失效后仍在一定范围内缓慢增加,熔覆层区断口形貌呈沿晶或穿晶特征,基体侧的热影响扩散区呈扇形解理断裂特征,远离界面的基体区域为具有大量韧窝的韧性断裂。The Ni-Co/WC-Graphite composite coating was fabricated by vacuum cladding.The microstructure and composition of the composite coating were characterized and analyzed by SEM and XRD.The bending behavior was studied through three point bending test,and the fracture characteristics,elements analysis and fracture mechanism were discussed.The results show that the whole composite coating consists of composite area,transition area,diffusion-fusion strip and heat-affected area.The WC particles well-distribute among the composite coating and form a 3D reticular microstructure characteristic.The main phases are Cr7C3,Cr23C6,Ni3Si,CrB,WC,C and γ-Ni-Co solid solution in the composite coating.The pearlite is the main phase at heat-affected area.There areγ-Ni-Co solid solution and intermetallics in fusion area and transition area.Three point bending test show that the load-distance curve presents linear change at the initial state,and then the slope of curve decreased.The composite coating debacle happens as the load reaches a maximum when the composite coating bears compress stress,and fracture happens as the load reaches a maximum when the composite coating bears tensile stress.The load increases slowly after thecomposite coating failure because of the forming of the transition area,diffusion-fusion strip and heat-affected area.The fracture characteristics present intergranular or transgranular at composite coating area.The fracture presents fan cleavage characteristics at the heat-affected area,and there are many dimples at substrate area.

关 键 词：Ni-Co/WC-G 复合熔覆层 微观组织 三点弯曲 断裂 

分 类 号：TG174.44[金属学及工艺—金属表面处理]