Preparation and characterization of La-doped Y3Al5O12 as a potential protective coating material against CMAS corrosion

Abstract

Mitigating calcium‑magnesium‑aluminum-silicate (CMAS) corrosion attack on thermal barrier coatings (TBCs) has attracted increasing interest. In this study, (Y1-xLax)3Al5O12 (x = 0, 0.1, 0.2, 0.3) were synthesized by the chemical co-precipitation method. The La-doped Y3Al5O12 was composed of Y3Al5O12 and LaAlO3 phases. As the La3+ doping concentration increased, the content of the LaAlO3 phase gradually increased. Compared to un-doped Y3Al5O12, the fracture toughness and Vickers hardness of Y3Al5O12 doped with 20 mol% La3+ increased by 54.9 % and 72.5 % respectively, reaching 2.88 MPa·m1/2 and 18.03 GPa. The thermal expansion coefficient of Y3Al5O12 doped with 30 mol% La3+ reached 9.79 × 10−6/K at 1000 °C, which was 7. 34 % higher than that of the un-doped Y3Al5O12. The CMAS corrosion resistance of (Y1-xLax)3Al5O12 gradually improved with the increase of LaAlO3 content. LaAlO3 promoted the formation of a dense apatite-spinel reaction layer and effectively inhibited the penetration of CMAS. (Y1-xLax)3Al5O12 (x = 0.1, 0.2, 0.3) can act as a potential protective coating material against CMAS corrosion.