INVESTIGATION OF LASER CLADDING CERAMIC-METAL COMPOSITE COATINGS - PROCESSING MODES AND MECHANISMS

The motion of ceramic particles in laser cladding ceramic-metal compos ites (LCCCs) is a very important factor which affects not only the dis tribution of the ceramic particles in the LCCCs but also the minimum s pecific energy needed to form LCCCs, as well as the choice of laser pr ocessing parameters. In this paper, the motion rules of the ceramic pa rticles in LCCCs have been investigated systemically by designing spec ial experiments. The results demonstrate that there are two typical mo tion modes of ceramic particles during the formation of LCCCs: one mod e is defined as the stirred mode, in which the ceramic particles move along with the liquid matrix alloy in the laser melting pool; the othe r mode is defined as the sintered mode, in which the ceramic particles do not move apparently, while the liquid matrix alloy infiltrates alo ng the surface of the ceramic particles to the bottom, so forming the LCCCs. The minimum specific energy needed for LCCCs with the stirred m ode is much less than that with the sintered mode. As far as a certain combination of the ceramic particles and the matrix alloys is concern ed, the motion modes of the ceramic particles in LCCCs depend not only on the composition of the matrix alloys and their physical and chemic al properties, but also on the kind, size, shape and the weight per ce nt of the ceramic particles. Thermodynamic analyses are described qual itatively which can explain these results very well.