Microstructure and thermal properties of a promising thermal barrier coating: YTaO4

High temperature gas turbine sealing can increase the thermal efficiency of a gas turbine. In this paper, monoclinic phase YTaO4 ceramics were fabricated via solid-state reaction. Phase composition and microstructures of the high-temperature-sintered YTaO4 ceramics were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman Spectroscopy. Specific heat capacity rose gradually as temperature increased, due to volumetric expansion and phonon excitations. The thermal diffusivities and conductivities decreased significantly due to the effects of the porosity and phonon scattering. However, the thermal conductivities of the specimens were lower than that of 7-8 wt% yttria-stabilized zirconia (7-8YSZ), and YTaO4 ceramics have better thermal stability than current (TBCs) material. The Vickers hardnesses of YTaO4 ceramics as a function of sintering temperature were lower than that of 8YSZ, indicating YTaO4 has better fracture toughness and thermal tolerance. The results demonstrate that YTaO4 ceramics would be an excellent candidate for use as a thermal barrier coating material for high temperature gas turbines. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.