Effect of the increase in the entrance convergent section length of the gun nozzle on the high-velocity oxygen fuel and cold spray process

摘要: Nozzle geometry, which influences combustion gas dynamics and, therefore, sprayed particle behavior, is one of the most important parameters in high-velocity oxygen-fuel (HVOF) thermal spray process. The nozzle geometry also cold method. flows entrance convergent section exhibit a relatively higher temperature and are subsonic; thus, this region suitable for heating particles. In study, numerical simulation experiments investigated effect gun on HVOF process changes inside nozzle, as obtained by studies, were related to coating properties. An Al2O3-40 mass% TiO2 powder was used experimental studies. change length (rather than barrel part or total length) had significant deposition efficiency, microstructure, hardness. efficiency hardness increased increased. On other hand, calculated measured velocity showed slight decrease. This will be applied design