Numerical modelling of CMAS infiltration and dimensionless numbers of anti-infiltration designs of thermal barrier coatings

Abstract

Resistance to calcium–magnesium–alumina–silicate (CMAS) infiltration and corrosion is a crucial problem for safely applying thermal barrier coatings (TBCs) in advanced aero engines. This work proposes a CMAS infiltration model based on the phase-field method to simulate the CMAS infiltration process in TBCs and analyse the influence factor. Further, a key dimensionless number called relative driving force $K=\frac{r\sigma \cos \left({\theta }_c\right)t_{\text{s}}}{\mu {ϛ}^{\text{2}}{h}_{\text{TC}}^2}$ was found to determine the CMAS infiltration depth using dimensional analysis. A criterion of K<2 was derived and was considered to be the evaluation standard of TBCs with excellent CMAS infiltration resistance. Based on K minimization, novelty TBCs with microstructure of S-shaped intercolumnar gaps and spherical pores are expected to significantly improve the resistance to CMAS infiltration and corrosion.