Designing oxidation resistant ultra-high temperature ceramics through the development of an adherent native thermal barrier

We present a design concept for developing ZrB2 -SiC-AIN composites with enhanced oxidative stability at ultra-high temperatures (similar to 2000 degrees C) and low pressures (100 Torr). The oxidative stability of these materials arises from a protective silica based scale. However, active oxidation of SiC above 1700 degrees C presents a challenge, which we circumvent through the in-situ growth of a zirconia layer that serves as a thermal barrier, ensuring that the effective temperature at the zirconia/Si rich subscale is less than the active oxidation temperature. The design concept is validated by a series of ultra-high temperature oxidation experiments under static as well as cyclic conditions. (C) 2019 Elsevier B.V. All rights reserved.