Abstract
The microstructure of ultra-high-temperature ceramics based on the ZrB2–SiC composition and a sintering additive (Si3N4) was investigated using XPS and AES techniques. These ZrB2–SiC–Si3N4 materials were treated in air plasma at high temperature (T > 1750 K) in the MESOX facility developed at the PROMES-CNRS laboratory (Moyen d'Essai Solaire d'OXydation for the measurement of atomic oxygen recombination coefficients). The surfaces were characterized before and after the air plasma treatment. Surface modifications were observed and induced by the oxidation process. The elementary composition was determined using AES and XPS. Core level spectroscopy (XPS) was used to determine the atomic composition and the nature of the chemical bonds from the Zr 3d3/2,5/2, Si 2p1/2,3/2, O 1s and C 1s photoelectron peaks. The microstructural analyses revealed the presence of oxide layers: Silica and zirconia compounds were detected at temperatures near 1800 K, and a zirconia compound was mainly detected above 2200 K.