Fabrication of yttria-stabilized zirconia aerogel for high-performance thermal barrier coating

Abstract

In this study, we successfully fabricated an yttria-stabilized zirconia (YSZ) aerogel using the sol-gel method and CO2 supercritical drying. We confirmed the successful thermal insulation function as a thermal barrier coating (TBC) on a high-temperature gas turbine surface. In order to evaluate the performance of the YSZ aerogel, the thermal conductivity and temperature profile were measured in addition to microstructure observation by scanning electron microscopy. The thermal conductivity of the YSZ aerogel was 0.212 W/m·K at 1000 °C, which is significantly lower than the reference values of YSZ materials. The low heat conduction is attributed to heat insulation by the fine pores and low heat conduction through the nanopore spaces in the aerogel structure. The heat insulation of the YSZ aerogel as the TBC was evaluated on a gas turbine blade material by monitoring surface temperature profiles on a heater at 300–700 °C. The heat-blocking performance of the YSZ aerogel coating was superior to that of a conventional YSZ TBC (by 30–50%). By comparison with a numerical calculation, the thermal conductivity of the YSZ aerogel coating was estimated to be 0.05 W/m·K, which is significantly lower (30–40 times) than that of the YSZ TBC used for commercial gas turbines. The porous structure of the aerogel was well preserved even after the high-temperature test confirming the good thermal stability. This study demonstrated that the YSZ aerogel is promising as a gas turbine TBC material.