Quantificação da evaporação de partículas de Alumina em um Plasma Térmico.

Abstract

When using powder particles in thermal plasma processes, partial evaporation of the particles may occur during plasma-particle interaction. Therefore, this research consisted of proposing the study of the parameters that cause evaporation with the aid of an experimental setup for the construction of an analytical model. To quantify evaporation, two experiments were performed. One experiment was the deposition process and the other without the deposition process. To develop the model, equations already existing in the literature were researched and compiled. In the results, it was possible to perceive that the evaporation in the experiments was significant. However, when the powder feed rate increases, there is a decrease in the evaporated mass, which causes a low evaporation rate. In the model, the equations for the energy required to reach the evaporation temperature and the evaporation rate depend on the mass. The fact that the equations depend on the mass makes it possible to use both the mass of the particle and also the mass injected into the plasma flame during the experiments. Therefore, what relates the equations to the experiments was the need to obtain an equation in which experimental parameters could be used to determine the energy and evaporation rate in the process as thermal plasma. The main contributions of the work are that the equations can be used for different materials, possibility of estimating the energy needed to evaporate and the evaporation rate, can be used in different processes with thermal plasma. In short, the determined model can be used for other materials, in addition to alumina, in the prediction of evaporated material as a function of the operating conditions of the plasma spray system. The results can be used in the production of nanoparticles by plasma spray, in addition to being able to help optimize the deposition of coatings by the plasma spray process, maximizing the deposition rate.