Influence of powder-feeding mode on microstructure of WC reinforced composite coating

WC reinforced Ni-based composite coating was prepared by using plasma surfacing process with two different power-feeding modes of synchronous feeding and back feeding.The microstructure,phase structure and chemical compositions were analyzed by scanning electron microscopy(SEM),X-ray diffractometer(XRD) and energy dispersive spectrometer(EDS).Results showed that the microstructure consists of WC particles embedded in hypoeutectic matrix.Compared with synchronous feeding,less dissolution of WC,less primary phases WC,W₂C with finer microstructure and greater concentration gradient of elements were observed in the composite coating with back-feeding process.