【摘要】 在ZG45表面采用真空熔覆技术制备了Ni-Co/WC复合熔覆层,通过SEM、EPMA和XRD观察并分析了熔覆层的显微组织结构和相组成,通过三点弯曲试验研究了熔覆层的弯曲行为,并分析了断口形貌和断裂机理。结果表明,WC颗粒在镍-钴基合金中呈现网状分布,熔覆层的主要组成相有WC、Cr7C3、Cr23C6、Ni3Si、Fe Ni3和镍-钴基固溶体;三点弯曲试验表明,Ni-Co基合金熔覆层与基体结合良好,即使熔覆层朝下承受拉应力时试样自拉应力最大的熔覆层表面开始产生延伸至基体内的纵向裂纹,并无沿结合界面的横向裂纹,而Ni-Co/WC复合熔覆层却在弯曲过程中与基体沿界面发生剥离;断裂试样的基体断口有大量韧窝,基体区域属于韧性断裂,而Ni-Co/WC复合熔覆层的断裂方式包括穿晶断裂和沿晶断裂。更多还原

【Abstract】 The Ni-Co / WC composite coatings were fabricated on ZG45 steel by vacuum sintering cladding.Microstructure and composition of the composite coatings were characterized by SEM,EPMA and XRD.The bending behavior and bending strength of the composite coatings were studied by three-point bending test.The results show that the WC particles are distributed in the Ni-Co alloy matrix forming a special 3D reticular microstructure.The main phases of the composite coatings are WC,Cr7C3,Cr23C6,Ni3 Si,Fe Ni3 and nickel and cobalt based solid solution.Three point bending test results show that the Ni-Co / WC composite coatings peel off along the interface between the coating and substrate,however,no transverse cracking is observed along the interface between the coating and substrate for the Ni-Co alloy coatings in the tension stress state.The dimple fracture morphology shows the ductile facture mechanism for the substrate,and the facture of the Ni-Co / WC composite coatings exhibits mixed- rupture characteristics of transgranular and intergranular fracture.更多还原