Effect of Feedstock Size on the Properties of WC-17Co Coatings

High velocity oxy-fuel (HVOF) spray technique has been employed to fabricate WC-17Co coatings. To achieve a high performance of mechanical properties and abrasive wear resistance, four types of WC-17Co powders with different feedstock particle sizes were investigated. The results show that the feedstock powder with finer particle size has higher velocity and temperature during the spraying process, resulting in a denser coating and a stronger splat-splat bonding. The micro-hardness of WC-17Co coating increases with the decreasing of feedstock size. The coating deposited by finer feedstock powder has superior abrasive wear resistance, due to the smaller porosity and boundary flaws on coating surface. However, coating fracture toughness could be affected by feedstock size if it is too small. Among all those investigated coatings, the one with medium particle size and narrow size distribution exhibits both excellent mechanical properties and wear resistance.