Evaporation recoil force during plasma arc spraying

Summary form only given. A particle´s surface is not heated uniformly during plasma arc spraying: that side of the surface, which faces the torch, is hotter than the opposite side. If the particle temperature is high enough so that substantial evaporation occurs, then imbalance of the vapor pressure gives rise to a net recoil force accelerating the particle toward the substrate. Estimations made for conditions, showed that the recoil force is comparable to the aerodynamic drag for iron particles in the range 20 mu to 60 mu. The effect is maximal for particles of 40 mu in diameter: smaller particles are heated more uniformly; larger particles are not hot enough