LaAlO3 as overlayer in conventional thermal barrier coatings

The performance enhancement of Thermal Barrier Coatings (TBC) towards higher service temperatures and longer service life will have a tremendous positive impact on the energy efficiency of turbines for various applications. In this work a study for the evaluation of LaAlO3 as an overlayer to the YSZ-based TBC is presented. Overlayers on TBC, are desirable in order to add functionalities, not exhibited by the YSZ, such as CMAS tolerance. However, their effect on the thermal cycling performance of the multi-layered system needs to be examined. NiCrA1Y bond-coated nimonic substrates were coated with Yttria Stabilized Zirconia (YSZ) delivered either by Atmospheric Plasma Spraying (APS) or by Suspension Plasma Spraying (SPS). On top of the YSZ layer, a LaAlO3 overlayer was developed directly from solution feedstock, employing Solution Precursor Plasma Spraying (SPPS). The structure of the LaAlO3 was confirmed by means of X-ray diffraction. The effect of the LaAlO3 overlayer on the thermal cycling was evaluated. For all cases the LaAlO3 improved the performance during thermal cycling at both 1100 degrees C and 1200 degrees C. (C) 2018 The Authors. Published by Elsevier Ltd.