Microstructure and mechanical properties of laser clad Ni-Cr-B-Si coating on copper alloy

The Ni-Cr-B-Si coating was clad on copper surface by CO2 laser cladding process.Microstructure and hardness of the clad layer were observed and analyzed by means of SEM,XRD,EDS,and micro-hardometer,and the erosion wear resistance of the coating and the substrate was also tested.The results show that the interface of the coating and substrate is metallurgical bonded,the microstructure is fine and compact,and above all it is crack-free,porosity-free,and slag inclusion free.The laser clad layer consists of equiaxed crystal,branch crystal,plane crystal and strengthening phase particles of Cr,B,Ni phases.Both the mass losses of the clad layer and the substrate are relatively higher when wear test at eroding angle of 60°.With increasing wearing time,the mass loss of the clad coating decreases and is less than that of copper substrate.Erosion wear resistance of the clad layer is obviously enhanced and is three times than that of the substrate.