Abstract―

Ultra-high-temperature ceramic (UHTC) materials with a density of 94.5 ± 1.3% have been manufactured by hot pressing a (HfB₂–30 vol % SiC)–5 vol % Y₃Al₅O₁₂ composite powder, which has been prepared sol–gel method, at a moderate temperature of 1850°C (holding time, 30 min; pressure, 30 MPa). The oxidation resistance of this ceramic has been studied at elevated temperatures under the effect of a supersonic dissociated air flow (on a high-frequency induction plasmatron). The maximum surface temperature has been ~2550°C. An analysis of the kinetics of temperature changes depending on the heat load indicate that, when five percent of Y₃Al₅O₁₂ by volume of HfB₂–30 vol % SiC is introduced into the ceramics, the thermal conductivity of the material decreases. This is not critical from the point of view of the stability of the obtained sample to single temperature drops of ~700–1400°C in a few seconds with sharp heating and cooling of the sample. A decrease of ~35–40% in weight loss of the (HfB₂–30 vol % SiC)–5 vol % Y₃Al₅O₁₂) sample has been noted as the result of exposure as compared with unmodified analogs. Due to the presence of Y₃Al₅O₁₂ in the initial ceramics, there is also a certain amount of the stabilized phase of cubic HfO₂ in the oxidized layer in addition to the monoclinic.

中文翻译：

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超音速离解气流影响下超高温陶瓷材料HfB 2 -SiC-Y 3 Al 5 O 12的行为

摘要-

密度为94.5±1.3％的超高温陶瓷（UHTC）材料是通过热压（HfB ₂ –30 vol％SiC）–5 vol％Y ₃ Al ₅ O ₁₂复合粉末制造的。制备的溶胶-凝胶法，温度为1850°C（保持时间为30分钟；压力为30 MPa）。在超声离解的气流（在高频感应等离子加速器上）的影响下，已在高温下研究了这种陶瓷的抗氧化性。最高表面温度为〜2550°C。对取决于热负荷的温度变化动力学的分析表明，当HfB的体积百分比为Y ₃ Al ₅ O ₁₂占5％时_{将2 –} 30 vol％的SiC引入陶瓷中，材料的热导率降低。从获得的样品在几秒钟内急剧加热和冷却到约700-1400°C的温度下降的稳定性的观点来看，这并不是至关重要的。与未经修饰的类似物相比，（HfB ₂ –30 vol％SiC）–5 vol％Y ₃ Al ₅ O ₁₂）样品的重量损失降低了约35-40％。由于初始陶瓷中存在Y ₃ Al ₅ O ₁₂，因此还存在一定量的立方HfO ₂稳定相 除单斜晶系外，在氧化层中也是如此。