Investigation on laser cladded nano-Y₂O₃ and cobalt based composite coating

A composite coating was prepared on a Ni-based alloy substrate by using laser cladding as well as surfacing welding with nano-Y₂O₃ and Co-based alloy powders.The microstructure and microhardness of the nano-Y₂O₃/Co-based composite coating were investigated using various techniques, e.g., scanning electron microscope(SEM).The wear resistance property and corrosion resistance property of the nano-Y₂O₃/Co-based laser cladding composite coating and pure surfacing welding were analysized by wear test and corrosion test.The results showed that the microstructure of laser cladding layer consists of a melt zone, a fine equiaxial zone and a coarse dendrite zone.The microhardness of the laser cladded coating was measured as HV868.9, superior to that of surfacing welding as HV512.8.Furthermore the wear resistance of laser cladding coating is 51.2 times stronger, with a total wear value of 0.5 mg compared to 25.6 mg obtained from the surfacing welding.In the corrosion tests of 10% HCl, 10% HNO3 or 10% NaOH solutions, the corrosion resistance properties of laser cladding coating is greatly enhanced.