BEHAVIOR OF ULTRAHIGH-TEMPERATURE ZrB₂-BASED CERAMICS IN OXIDATION

Abstract

Ultrahigh-temperature ZrB₂-based ceramics with different sintering additives for ex-treme conditions were developed. Their strength characteristics, phase composition, and structure were examined. The ceramics were oxidized in air at 1250 and 1550 °C. In addi-tion, the most stable composites were subjected to temperature-cycle test in a flow of aviation fuel combustion products in a temperature range of 1400–1500 °C. All materials have high oxidation resistance. The method used to produce samples influences their oxidation behavior: materials produced by vacuum hot pressing show higher oxidation resistance than those produced by hot pressing in a CO–CO₂ atmosphere, probably because of their higher final density. The best results were obtained when ZrB₂ was sintered with the simultaneous introduction of MoSi₂ and CrB₂.