In situ formation of MoSi 2/SiC composite coating on pure Al by laser cladding

Abstract

In order to improve resistance to high temperature and wear resistance of pure aluminum, laser-cladding experiments were conducted on a 3 kW continuous wave CO 2 laser to produce in situ synthesized molybdenum silicide (MoSi 2)/SiC composite coatings on pure aluminum. The laser consolidified microstructure and phase evolution were investigated using scanning electron micrograph and X-ray diffraction (XRD). The in situ formation of MoSi 2/SiC was carried out by adding a mixture of Mo, Si and C precursor powder layer followed by melting the layer and substrate under a laser beam. The experimental results showed that these compounds, MoSi 2 and SiC, can be formed from three distinct powders of Mo, Si and C on Al alloy, and, provided that supplied energy is sufficient to start the reaction between the initial products, a good metallurgical bond between coating and the substrate can be achieved. The microstructures of the coating were composed of MoSi 2, Mo 5Si 3 and SiC phases. The microhardness of coating was about 12 times that of the aluminum substrate, the maximum value reached HV 0.2 1200.