In situ formation of MoSi2/SiC composite coating on pure Al by laser cladding

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 CO2 laser to produce in situ synthesized molybdenum silicide (MoSi2)/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 MoSi2/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, MoSi2 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 MoSi2, Mo5Si3 and SiC phases. The microhardness of coating was about 12 times that of the aluminum substrate, the maximum value reached HV0.2 1200. (C) 2003 Elsevier Science B.V. All rights reserved.