COMPUTER SIMULATION OF ZrO_2+8Y_2O_3 AND AI_2O_3 POWDER PARTICLES HEATING UNDER PLASMA SPRAYING

摘要

1) Mathematical model for simulation of powder particle heating and acceleration in a plasma jet with the particle evaporation and diameter reduction is developed. Choice of evaporation model strongly depends on pressure of surrounded gas. For low pressures conditions Hertz-Knudsen law is applied. For atmospheric pressures developed model is based on vaporisation with backpressure. 2) An original software with a database for material properties has been developed for practical realisation of models. The software allows us to conduct "start-to-finish" simulation of plasma spraying with data transferred from one model to the other, and independent calculation of separate models, using the intermediate calculation results stored in the database. 3) With the software developed, the process of stabilised zirconium oxide and aluminium oxide coating plasma spraying was simulated. Results of model investigation are showed about reasonable simulation results. For example, velocity of particles strongly depends of its diameter, the evaporation to the vacuum goes more quickly and the mass flow from the particle surface is greater as atmospheric pressure, acceleration and melting of the particle with diameter 20, 40 μm more intensive than 80 μm, ets. 4) Next stage of models improvement is experimental verification and transformation for 3D plasma jet simulation.