Rare-earth elements improving the corrosion resistance of YSZ/CMAS heterojunction with stacking faults: First-principles calculation

Abstract

Stacking faults cannot be fully eliminated from yttrium partially stabilized zirconia (YSZ) ceramic coatings. However, their influence on the corrosion resistance of YSZ ceramics has remained unclear up till now. In this study, the impact of stacking faults on the corrosion resistance of YSZ with or without Nd dopant in CaO, MgO, Al2O3 and SiO2 (CMAS) melts was characterized via first-principles calculations. As expected, the stacking faults decrease the corrosion resistance of YSZ, especially at the saddle point along the slip way within the YSZ(111)V surface. Moreover, the Nd dopant can increase the corrosion resistance of YSZ due to its enhanced structural stability and enlarged wetting angle. Thoroughly analyzing the growth of stacking faults, it is found that the most pronounced effect of Nd dopant on the corrosion resistance of YSZ occurs only at the initial and final stages, whereas being less noticed at the saddle point of the slip way of faults. In addition, compared to the earlier studies, it is established that the largest penetration depth within the ceramic is achieved by Si ions, which broadens the knowledge about the main corrosion factors, as well as reveals the weakest O-Ca bond and the largest diffusion constants of Ca and Mg ions. Thus, the findings of this work open up new prospects for understanding the corrosion mechanism of YSZ TBCs in CMAS melt.