RESPONSE OF AGGLOMERATED, MULTICERAMIC PARTICLES TO INTENSE HEATING AND COOLING FOR THERMAL PLASMA SPRAYING SIMULATION

The melting and solidification of small, alumina–titania particles to intense heating and cooling is predicted. Due to the porosity of the original material, each particle can shrink upon melting, which in turn affects the thermal transport during processing. Due to the very high temperatures associated with ceramic phase change, as well as the extremely small length and time scales of the particle and process, two limiting cases are considered here. Specifically, it is assumed that either (1) the particle shrinks with no resistance to material flow or (2) the particle size is constant. Parametric simulations reveal the sensitivity of the predicted thermal response to each assumption, and to various process parameters. The particle model is coupled to an existing plasma spray model to demonstrate how the overall model can be used to simulate the processing of new, nanostructured materials.