Volcanic ash infiltration resistance of new-generation thermal barrier coatings at 1150 °C

Abstract

The recent developments in advanced materials for thermal barrier coatings (TBCs) have put thrust towards the progress of new materials due to their superior performance over the state-of-the-art yttria-stabilized zirconia (YSZ). Lanthanum cerate (La2Ce2O7, LC) is one of the promising candidates used against the infiltration of calcium magnesium alumino-silicate (CMAS) melt. For a highly efficient low thermally conductive material, gadolinium oxide doped lanthanum cerate ((La0.9Gd0.1)2Ce2O7, Gd-LC) was synthesized as a new aspirant. Deposits of atmospheric plasma sprayed (APS) LC, Gd-LC coatings were generated, and their interactions against the infiltration of volcanic ash were studied. Both the coatings formed the apatite phase interaction layer, with a considerable quantity of anorthite and spinel phases. On comparison, Gd-LC showed significantly more resistance than LC coatings because of the presence of Gd apatite in Gd-LC coatings. Further, we developed Gd-LC single layer, double-layer, and composite hybrid coatings by employing APS and solution precursor plasma spraying process (SPPS). Phase evolution and microstructural features were studied and are discussed in detail.