Abstract
Ceramic powders such as zirconia and titania are especially useful in their application as thermal barrier coatings, but are also useful in the production of more advanced coatings such as the dye-sensitized solar cell and functionally gradient prosthetic coatings. Due to their low thermal conductivity large temperature gradients through the powder particles are experienced during plasma spray deposition. As a result the particles often impinge at the substrate in a semi-molten form, which in turn substantially affects the final performance characteristics of the coating. This paper firstly summarizes some simulations and key results for completely solid and completely liquid particles. The modelling of semi-molten droplet impingement is then outlined, which is applicable to ceramic powders. The study examines the semi-solid impingement process during impact, spreading and solidification, and contributes to the growing insight being provided by numerical simulations on the topic of particle impingement in thermal spraying.
