Microstructure and performance of WC–Co–Cr coating with ultrafine/nanocrystalline structures

The WC–10Co–4Cr composite powder was synthesized firstly. Then the composite powder was agglomerated to prepare thermal spraying feedstock. The ultrafine/nanostructured WC–10Co–4Cr coating was prepared by high velocity oxygen fuel thermal spraying. The phase constitution, elemental distribution and microstructure of the coating were characterized by X-ray diffraction and transmission electron microscopy, respectively. The wear resistance and corrosion resistance of the prepared composite coating were tested. The results show that the main phases of the coating include WC, binding phase with partial amorphous structure, with a little W 2 C and Co(Cr) coexisting. The distributions of Co and Cr elements from the phase boundary to the eutectic area then to Co zone were analyzed quantitatively. The mechanisms for the formation of the microstructure and effects of Cr on the performance of the composite coating are proposed.