COARSE CEMENTED WC PARTICLE CERAMIC-METAL COMPOSITE COATINGS PRODUCEDBY LASER CLADDING

Coarse cemented WC particle (600-900 mum) ceramic-metal composite coat ings with a thickness of 1.2-1.5 mm were cladded on 20Ni4Mo steel surf aces using a laser of power 2 kW, diameter 5 mm and traverse speed 4-2 0 mm s-1. The weight fraction of WC particles was 67 wt%. Compared wit h the behaviour of cemented WC particles of the same size and ratio in atomic hydrogen welded coating (AHWCs), the WC particles in laser-cla dded ceramic-metal coating (LCCCs) show a uniform distribution in the molten zone. The microhardness of WC particles in LCCCs is 13.7-16.2 G Pa, and their sizes are almost unchanged, which indicates that little heat damage occurs during laser cladding. The abrasive wear results sh owed that LCCCs have superior wear resistance to AHWCs. The wear mecha nisms for LCCCs and AHWCs are analysed and compared.