Numerical Analysis of Solution Mixture and Torch Design in High-Velocity Suspension Flame Spraying

High-velocity suspension flame spraying (HVSFS) is used for direct processing of submicron and nano-scaled particles to achieve dense surface layers in supersonic mode with a refined structure, from which superior properties are expected. The application of solutions as a carrier fluid for nano-particles in thermal spray systems is a new approach that requires some thermo-physical and chemical optimization. Three dimensional modelling and analysis of the combustion and gas dynamic phenomena of the three-phase HVSFS process is performed in this study for an industrial TopGun^®-G torch, based on a numerical model for a conventional HVOF process. Parameter analysis of the solution mixture (proportion between aqueous and organic solvent) in a suspension is performed as well as analysis of particle deposition at the internal wall of the combustion chamber depending on the torch design, leading to more homogeneous flow properties for an improved HVSFS torch.