Infiltration brazed core-shell WC@NiP/NiCrBSi composite cladding

In this study, a novel Ni-P-coated WC/NiCrBSi composite cladding was prepared on a carbon steel substrate through high-temperature vacuum brazing technique with the aim of improving the wear properties of the surface. In order to improve the wettability of WC particles by a liquid phase (NiCrBSi alloy), Ni-P layer was deposited on carbide particles by electroless plating. This layer assisted to fabricate a thick coating with very low porosity, improving adhesion strength between ceramic particles and the matrix. The morphology, crystal structure and microstructure of coated carbides and the resultant composite cladding were characterized by field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. Thin electroless plated Ni-P shell with a thickness about 50-150 nm, were coated on WC particles. In the claddings, a uniform and homogenous distribution of WC particles in Ni-based matrix was observed. The pin on disk wear test was carried out to investigate the wear behavior of the fabricated cladding reinforced with and without Ni-P coated WC particles. The results indicated that the resistance against crack initiation and propagation significantly improved by using Ni-P layer in the sintered cladding. This cladding exhibited very low wear weight loss than conventional brazed cladding.