Diode laser cladding of Co-based composite coatings reinforced by spherical WC particles

摘要

A laser cladding system consisting of a direct diode laser with the flat-top beam profile and an off-axis powder injection nozzle has been used to fabricate Co-based (Stellite 6) metal matrix composite coatings reinforced by spherical-shaped WC particles. Non-porous coatings with the WC fraction of about 50 vol.% and a low dissolution of the WC particles in the matrix have been obtained. The heat input level affects the degree of WC dissolution and the matrix mean free path between the embedded WC particles. Comparative erosion tests between the metallic Stellite 6 and composite Stellite 6/WC coatings showed that the composite coatings exhibit a superior erosion resistance only at the oblique impingement condition. Generally, a low erosion resistance of the composite coatings at the normal impingement is mainly attributed to a very smooth interface between the spherical-shaped WC particles and the matrix alloy.