Design of cold spray nozzles for inner wall polymer coating fabrication

Corrosion of pipes is a major issue for the transport sustainability of gas, water. Therefore, it is needed to protect them efficiently. Recently, perfluoroalkoxy alkane coating by cold spray (CS) technique showed great potential in terms of high deposition efficiency and super-hydrophobic properties, making it an ideal material for the protection of the pipe’s wall. While the outer wall is easily accessible with a commonly-used straight nozzle, it is not the case for the inner wall, where a specific nozzle needs to be designed. In this work, two nozzle shapes were investigated through numerical simulation, namely, elbow-shaped and spring-shaped nozzles. Both nozzles present a curvature that allows the coat of the inner wall of pipes with an optimal spray angle of 90°. The simulation results showed that the particle velocity and temperature of elbow-shaped and spring-shaped nozzles could reach the straight nozzle’s target value. Moreover, the spring-shaped nozzle has a higher particle velocity while the elbow-shaped nozzle has a more uniform particle distribution. These first observations show that the elbow-shaped nozzle appears to be more suitable to coat the inner wall of pipes. Therefore, fabrication of the nozzle as well as experimental validation will be the aim of future researches.