Structure and cavitation erosion behavior of HVOF sprayed multi-dimensional WC-10Co4Cr coating

A new kind of multi-dimensional WC-10Co4Cr coating which is composed of nano, submicron, micron WC grains and CoCr alloy, was developed by high velocity oxy-fuel (HVOF) spraying. Porosity, microhardness, fracture toughness and cavitation erosion resistance of the multi-dimensional coating were investigated in comparison with the bimodal and nanostructured WC-10Co4Cr coatings. Moreover, the cavitation erosion behavior and mechanism of the multi-dimensional coating were explored. Results show that HVOF sprayed multi-dimensional WC-10Co4Cr coating possesses low porosity (≤0.32%) and high fracture toughness without obvious nano WC decarburization during spraying. Furthermore, it is discovered that the multi-dimensional WC-10Co4Cr coating exhibits the best cavitation erosion resistance which is enhanced by approximately 28% and 34%, respectively, compared with the nanostructured and bimodal coatings in fresh water. The superior cavitation resistance of multi-dimensional WC-10Co4Cr coating may originate from the unique micro-nano structure and excellent properties, which can effectively obstruct the formation and propagation of cavitation erosion cracks.