Microstructural Analysis of Nanostructured WC-12Co Coatings Sprayed by HVOF

Research on nanostructured WC-12Co coatings has been emphasized nowadays,and study on coating's microstructure and the influencing factors is beneficial to enhance the coating properties.Nanostructured,multimodal and conventional WC-12Co ceramic coatings were deposited by high velocity oxy-fuel spray(HVOF) and the structures of the coatings such as microstructures and phase compositions were analyzed by SEM and XRD.Finally the mechanisms and factors of decarburization of WC particles in spraying were explored.Research results show that microstructures of nanostructural and multimodal WC-12Co coatings deposited by HVOF are dense,better adhesive strength and little porosity than conventional one.As well,it is found that although obvious decarburization of WC and crystal size growth occurred during spraying multimodal and nanostructured WC-12Co powders in comparison with conventional coating,the decarburization of WC for the nanostructured powder is more severe because of the increasement in nano size WC amount,and the decarburization degree of nanostructured WC-Co is not only influenced by spray parameters,but also depended on the powder structure characteristics.