A study of the microstructure and oxidation behavior of alumina/yttria-stabilized zirconia (Al2O3/YSZ) thermal barrier coatings

► We have produced a dense Al2O3/YSZ layer on the surface of YSZ coatings. ► The ionic conductivity of top-coat was decreased due to the presence of Al2O3. ► The Al2O3/YSZ top-coat showed better oxidation resistance compared to YSZ coating. ► The Al2O3/YSZ top-coat showed higher t′-phase stability compared to YSZ coating.