Effect of binder metals on structure and properties of WC ceramic-metal composite coatings by laser-induction hybrid rapid cladding

摘要

In order to choose the appropriate binder metals for ceramic metal composite coating produced by laser-induction hybrid rapid cladding, the effect of binder metals on structure and properties of WC ceramic metal composite coatings were investigated. The maximum laser scanning speed and the maximum powder feeding rate of Ni-based + 50 wt.% WC composite coating can be increased to 1500 mm/min and 65.3 g/min, which are 1.5 and 1.23 times higher than those of Fe-based + 50 wt.% WC composite coating, respectively. Most of the WC particles are not dissolved completely and still preserve their eutectic structure in Ni-based metallic matrix, in which only a few of WC particles are completely dissolved and the carbides with dendritic and blocky shapes are dispersedly precipitated. However, WC particles are dissolved almost completely and the coarse herringbone M6C (M = W, Fe, Cr and Ni) eutectic carbides are precipitated in Fe-based metallic matrix. Moreover, the dissolution rate of WC in Fe-based alloy solvent is higher than that in Ni-based alloy solvent during laser-induction hybrid rapid cladding. The precipitation of coarse herringbone M6C carbides can accelerate the dissolution of WC during laser-induction hybrid rapid cladding. As a result, the microhardness and wear resistance of Ni-based WC composite coating are much higher than that of Fe-based WC composite coating.