等离子熔覆镍包WC/Fe-Cr-B-Si复合涂层微观组织

采用等离子熔覆技术在Q235钢表面制备了镍包WC含量(质量分数)分别为10%、30%、50%的WC/Fe-Cr-B-Si复合涂层。采用OM、SEM、EDS、XRD等手段研究了涂层的组织,利用显微硬度计测试了涂层的显微硬度。结果表明,添加10%镍包WC的涂层中WC几乎全部溶解,而在含30%、50%镍包WC涂层中均存在未溶解的WC,且在复合涂层微观组织演变中发现了明显不同的凝固特征,含10%、30%镍包WC的涂层主要是枝晶和枝晶间共晶的亚共晶组织;而在含50%镍包WC的涂层中是以初晶Fe3W3C为主和过共晶组织。添加10%、30%、50%镍包WC的复合涂层显微硬度分别为560~600、650~800、920~1100 HV0.2,硬度随WC含量的增加而提高。

Microstructure of nickel-clad WC/Fe-Cr-B-Si composite coating by plasma cladding

The microstructure evolution of the cladding layer formed by plasma cladding Fe-Cr-B-Si with 10%,30% and 50% nickel-clad WC respectively on Q235 steel were investigated by OM,SEM,EDS,XRD,and the microhardness of the coatings was tested by microhardness tester.The results show that the nickel-clad WC particles are almost entirely melted into the composites coating when 10% nickel-clad WC is added,while the nickel-clad WC particles still exist partly in the coatings when 30% and 50% nickel-clad WC are added,and significantly different solidification structures are found in the microstructure evolution of the coating.The layers with 10% and 30%WC are mainly consisted of dendrites and inter-dendrite eutectics,while the layer with 50%WC is consisted of Fe_3W_3 C carbide dendrite and hypereutectic structure.The microhardness of the coatings added 10%,30% and 50%WC reaches 560-600,650-800 and 920-1100 HV0.2,respectively.So the microhardness increases with increasing of WC content in the layer.