Effect of hypersonic flow chemical composition on the oxidation behavior of a super-strong UHTC

A super-strong ZrB2 ceramic containing WC and SiC was tested in a supersonic arc-jet wind tunnel by exposure to flows with two chemical compositions, simulated air or pure nitrogen, at temperatures of 2650 and 2800 K. Temperature jumps of 500-600 K were observed in both environments at constant flow conditions. SEM analyses revealed that oxygen in the high-enthalpy flow retards the material consumption owing to the formation of partially protective glass. Then, it appears that even 5 vol% of W-compounds is sufficient to modify the subscale oxide configuration and form a cell-like multi-layered architecture typical of tungsten, rather than that typical of ZrB2.