Influence of laser cladding parameters on microstructure and wear-resistance of Ni-based alloy coatings

Ni based alloy coatings and Ni/WC composite coatings were prepared on Q235 steel by thermal spray and larser cladding.The influences of the laser power on the properties of coatings were widely studied.The results showed that the high quality coatings with uniform WC particles distribution,low dilution and good combination with the substrate can be obtained under the optimized laser power.In the Ni/WC composite coatings,WC particles partly dissociated at the edge,and many needle like dendrites grew epitaxially from the surface of the partially melted WC particles under the proper laser power.This can improve the microhardness of the coating and significantly combined the WC particles with the matrix alloy.When the laser power is too large,WC particles at the top of the coating were burned and remained WC particlels sank to the bottom of coating.Acoordingly,there is a sharp transition in hardness at the interface between the coating and the substrate.It easily brings about cracks and fatigue failure,and does not help to improve the wear resistance of the coating.