Laser cladding of SiC-reinforced MMC coatings

Authors have successfully produced SiC reinforced metal matrix composite (MMC) coatings by using a 2 kW Nd: YAG laser on the substrates of 40Cr steel and an Aluminum alloy, and carried out microstructure analysis and performance testing of the coatings. There are two forms of SiC in the experiment: particle and fiber. By adjusting the adding content of SiCp (5%, 20%, 30%, 40%, 50%, 60%) and of SiCf (40%, 50%), evolution of SiC of different forms during laser cladding, existing forms of SiC in cladding layers and affection on hardness of cladding layers are studied. The results show that during laser cladding, SiC of different forms is decompounded partially； with the increasing of the SiC adding content, the quantity of unmelted SiC increases and hardness of cladding layers improves. Comparing the hardness of SiC particle reinforced coating with the SiC fiber reinforced one, the reinforcing effecting of SiC fiber is better； the main reasons that bring hardness remarkable improvement are disperse reinforcement of un-melt SiC and precipitation FeSiC, and solution reinforcement of decompounded Si, C.