SYNTHESIZING OF WC/NI HARD ALLOY COATING BY LASER CLADDING WITH POWDER FEEDING AND THE GROWTH MORPHOLOGY OF WC CRYSTALS

摘要

The WC/Ni hard metal coating was synthesized by laser cladding with coaxial feeding of its formation elements W/C/Ni powder mixture, basing upon the unique physical and chemical metallurgy within the melt pool. A plump shape WC/Ni layer free of cracks was obtained. The composition distribution of the clad layer, the dissolution behavior of the adding W and C/Ni clad powders and the synthesizing of WC were investigated. The microstructure, phase and WC growth morphology were analyzed. The WC particles synthesized by laser have rectangular or quadrangle cross-section shape with size of 2～30μm. Step, rotary and cross growth morphologies of WC formation were observed in the synthesized layer. In addition to the WC, the synthesized layer contains phases like W{sub}2C、CW{sub}3、FeW{sub}3C、Fe{sub}6W{sub}6C、W{sub}3O、 W、C、（Fe，Ni）.