HU Bing ¹, HE Zi ¹, ZHANG Jingxiarr, LU Yijurr, WANG Ping ², WU Yuping ², LIN Pinghua ², XIE Guozhi ²

(1.Electron Microscope Demonstrating Co. Lab of Nanjing Agricultural University and  Techcomp, Nanjing Agricultural University,  210095; 2.Department of Materials and Engineering, Hehai University, Nanjing 210098)

Abstract: The thick Ni-coated WC coating,in a matrix of Nickel-based alloys,was deposited on the low carbon steel by plasma cladding equipment.A pre-placed layer of uniform mixture,Ni-coated WC powder and Nickel-based alloy powder, on the substrate steel was melted at the high temperature of the plasma jet.Different coatings are made with three different weight fractions of 5%,10% and 15%.The coating composition,microstructure and microhardness were analyzed by X-ray diffraction (XRD),optical microscopy (OM),scanning electron microscopy (SEM),energy-dispersive spectrometer (EDS) and microhardness testing.The experimental results show that the metallurgically bond was formed  between the coating and substrate.The microstructure of the clad coating consists of dendrite,interdendrite eutectic.SEM shows that the Ni-coated is a very effective method to protect the WC powder.The XRD results show that the phases consist of y-Ni,carbides,such as M₂₃C₆ and M₇C₃ and boride, such as Fe₂B, Fe₃B phases.It was found that the plasma zone has a higher microhardness value with the content of Ni-coated WC powder increasing.

Keywords: WC,plasma cladding equipment,plasma zone