Simulation of melted state of particles in plasma spray

Melted state of flying ZrO₂ ceramic particles in plasma spray has been investigated in this paper by employing numerical simulation methods. Calculations are carried out for two kinds of single particle with diameters of 30 μm injected in typical plasma spraying conditions. Surface temperature histories of the flying particles, inner thermal state, temperature gradient as well as phase change of the particles of various sizes during their flight are successfully predicted. Based on these results, the spraying distance is discussed also, which can be classified into three regions, such as no melted, partially melted and completely melted zones. Only if the particles enter into completely melted zone, it is possible to form dense and idea coatings. These methods and results will bring insight into the practical thermal spray operations.