Effect of Particle and Injection Parameters on the Performance of a Dual-Stage High-Velocity Oxygen Fuel Thermal Spray System

For temperature-sensitive material (such as titanium) coatings, recently developed high-velocity oxygen fuel dual-stage thermal spray systems offer better control of particle oxidation and production of various coating structures. These advantages of the dual-stage thermal system are significantly influenced by the state of the coating particles being injected. Hence, the objective of the present study is to investigate the effects of particle size, shape, injection velocity, and injection angle on a dual-stage thermal spray system by employing a comprehensive mathematical model. The results demonstrate that the particle size, shape, injection velocity, and injection angle affect the particle velocity and temperature, which in turn may affect the coating quality. The results show that smaller particles have higher temperatures and velocities owing to decrease in particle thermal and mass inertia. Spherical particles have higher temperature and lower velocity than the non-spherical particles because of lower drag. The particle velocity and temperature also increase with the increase of the injection velocity. Similarly, the particles injection angle also plays an important role. Higher particle temperatures and velocities outside of the barrel are obtained if the particles are injected at oblique angles to the main gaseous flow.