Suspension High-Velocity Oxy-Fuel (S-HVOF) Spraying with a Liquid-Fueled Torch

Suspension High-Velocity Oxy-Fuel (S-HVOF) spraying has seen increasing interest within the last decades, as it offers better coating microstructure control than powder spraying but also more favorable spraying conditions for cermets (e.g. WC-Co) that could otherwise risk oxidation or decarburization via Suspension Plasma Spraying (SPS). Nevertheless, most efforts have been focused on gas-fueled HVOF torches, with few reports on liquid-fueled HVOF torches that could offer higher velocities and lower flame temperatures. This work aims to explore the HVOF spraying of suspensions with a liquid-fueled (kerosene) WOKAJET-410 torch via the spraying of an Al₂O₃ suspension. Spraying of individual spots was performed to identify asymmetry in the spray plume, and spraying condition parameters were correlated to the suspension injection pressures. The microstructure of the individual spots was characterized and first indications into the coating build up mechanisms were determined.