Suspension HVOF spraying of TiO2 using a liquid-fueled torch

Abstract TiO 2 coatings were deposited by suspension spraying using, for the first time, a liquid (kerosene)-fueled torch. A ball-milled TiO 2 powder with d 50  = 5.67 μm was dispersed in isopropanol and, using a peristaltic pump, it was radially delivered in between the combustion chamber and the conical expansion barrel of the HVOF torch, replacing the conventional dry powder ports with adapted liquid injection nozzles. Coatings are made up of highly flattened splats, whose diameter varies reflecting the size distribution of the feedstock powder, and −4  mm 3 /(N·m) to −6  mm 3 /(N·m) when the temperature increases from ≈25 °C up to 450 °C. The denseness of the coatings allows them to produce micro-scale plastic deformation with limited brittle fracture.