Modeling molten droplet spreading and infiltration into non-isothermal thermal barrier coatings

•An integrated model is introduced incorporating simultaneous droplet spreading, wetting interactions, heat transfer, and liquid infiltration with temperature-dependent viscosities in unsaturated porous media.•This study shows that CMAS droplets of a size encountered by real gas turbines will lose their initial thermal energy soon after impact on a TBC and have negligible influence on the overall infiltration behavior.•The temperature gradient within the TBC topcoat has a substantial impact on the CMAS infiltration rate. An anisotropic microstructure can significantly affect the lateral spreading and final penetration depth but has an insignificant influence on the initial infiltration rate.•Heterogeneous structures such as bilayer and multilayer structures can limit and delay vertical infiltration by diminishing the vertical pressure gradient and increasing the resistance to fluid flow.