Abstract The aim of this paper is to develop a model that describes the heating of the porous aluminum oxide particles in the plasma jet of the APS process. The initial calculation of the sintering time of this fine particle in solid and liquid phase states (1800 K) is estimated. This time is in the range of seconds for sintering in the solid state and in the range of nano seconds for sintering in the liquid state. It is found that the effect of sintering within a particle during its flight in the plasma jet can be neglected. The calculation of the temperatures on the surface, the center, and the point of the melt front is carried out for particles with more or less porosity. Paper includes a German-language abstract.

Abstract Most metallic and ceramic splats show temperature-dependent behavior when they hit the substrate. The results suggest temperature-dependent wetting properties. In this paper, surface morphological influences due to oxidation of the substrate on the flattening behavior of free-falling droplets are fundamentally investigated. The surface properties are examined by means of AFM. The morphology of the substrate influences the flattening behavior even with changes in the nanometer range. Paper includes a German-language abstract.

Abstract The trajectories and properties of plasma-sprayed particles are influenced by a number of parameters. However, only a few of these can be set experimentally, such as the composition of the process gas or the injection speed. However, it is impossible to vary only individual parameters for a more detailed investigation of the relationships. This, however, allows the process simulation, which has proven to be an excellent tool for such investigations and has led to new knowledge about the process. This article presents simulation results that show the influence of spray and injection parameters on particle properties in APS. First, the overall process is subdivided into the sub-processes burner, plasma free jet, and particle flight. Then results of flow simulations are presented, and flow influences on the particle trajectories are shown. Finally, results are presented which influence the injection conditions on the powder. Paper includes a German-language abstract.