Thermal Insulation of YSZ and Erbia-Doped Yttria-Stabilised Zirconia EB-PVD Thermal Barrier Coating Systems after CMAS Attack

Germain Boissonnet; Christine Chalk; John R Nicholls; Gilles Bonnet; Fernando Pedraza

doi:10.3390/ma13194382

Thermal Insulation of YSZ and Erbia-Doped Yttria-Stabilised Zirconia EB-PVD Thermal Barrier Coating Systems after CMAS Attack

Materials (Basel). 2020 Oct 1;13(19):4382. doi: 10.3390/ma13194382.

Authors

Germain Boissonnet¹, Christine Chalk², John R Nicholls², Gilles Bonnet¹, Fernando Pedraza¹

Affiliations

¹ Laboratoire des Sciences de l'Ingénieur pour l'Environnement (LaSIE UMR-7356 CNRS), Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle, France.
² Surface Engineering and Nanotechnology Institute (SENTi), Cranfield University, College Rd., Wharley End, Bedford MK43 0AL, UK.

Abstract

The impact of small deposits of calcium-magnesium-aluminium silicates (CMAS) on the top of thermal barrier coatings (TBCs) made of yttria-stabilised zirconia (YSZ) produced via electron-beam physical vapour deposition (EB-PVD) is shown to play a role in the microstructural and chemical stability of the coatings; hence, it also affects the thermal insulation potential of TBCs. Therefore, the present work investigates the degradation potential of minor CMAS deposits (from 0.25 to 5 mg·cm^-2) annealed at 1250 °C for 1 h on a novel Er₂O₃-Y₂O₃ co-stabilised ZrO₂ (ErYSZ) EB-PVD TBC, which is compared to the standard YSZ coating. Due to the higher reactivity of ErYSZ coatings with CMAS, its penetration is limited in comparison with the standard YSZ coatings, hence resulting in a better thermal insulation of the former after ageing.

Keywords: Erbia-yttria co-stabilised zirconia; electron-beam physical vapour deposition (EB-PVD); thermal barrier coatings (TBCs); thermal diffusivity; yttria-stabilised zirconia (YSZ).