Microstructure and dry sliding wear of laser clad WC_p/Ni-Cr-B-Si-C alloy composite coatings

WC_p reinforced Ni-Cr-B-Si-C composite coatings were deposited on AISI1045 steel by laser. The microstructure of the typical coating containing 30vol-% WC particulate was investigated using XRD, SEM and TEM. It was found that partial WC dissolved and decomposed in the laser melt pool during the melting stage of the cladding. The rapidly solidified microstructure of the laser melt is composed of metastable bar-like α-W₂C, blocky β-W₂C and quadrilateral η carbide MoC precipitate distributed in Ni/Ni₃B lamellar eutectic. Dry sliding wear tests suggested that the composite coating containing about 30vol-% WC particulates resist wearing most effectively.