Cold Spray Deposition of a Core-Shell Structured WC-Co Coating

In this study, cold spraying is used to develop WC-Co coatings with a WC-10Co core as reinforcement and a Co-rich WC-Co matrix as the binder. Core-shell structured powders were prepared by mechanical milling and coating samples were deposited by cold spraying. Post-spray annealing was carried out to further modify the coating microstructure. WC-Co coating microstructure and mechanical properties were investigated along with various structure-property relationships. It was found that a WC-Co layer with a porosity of only 0.7 % was realized by cold spraying the mechanically milled powder and that annealing at 900 °C for 2 h resulted in a remarkable improvement in fracture toughness with no evident change in hardness.