Abstract

Porous HfB₂–65 vol % SiC samples (porosity 34.5%) were produced by reactive hot pressing of HfB₂–(SiO₂–C) composite powder at 1800°C (heating rate 10 deg/min, holding duration 15 min) and 30 MPa. Using a high-temperature induction plasmatron, their resistance to oxidation by a supersonic dissociated air flow was studied (the heat fluxes in the course of the experiment were varied from 363 to 779 W/cm²). The observation of the temperature distribution over the surface of the sample during the experiment showed that a sharp increase in temperature from ~1770–1850 to ∼2600°C in the samples under investigation occurred at lower heat fluxes and shorter treatment times than that in denser HfB₂–30 vol % SiC samples (porosity 9–11%). This indicated that increasing the density of the HfB₂–SiC material and also increasing the silicon carbide content reduced the oxidation resistance. However, the fact that the studied sample withstood 37-min exposure to a high-enthalpy dissociated air flow (including 27 min at a surface temperature of 2560–2620°C) without destruction or complete oxidation makes it possible to assign it to ultra-high-temperature materials.

中文翻译：

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超音速气流氧化富含碳化硅（65体积％）的多孔HfB 2 -SiC超高温陶瓷材料

摘要

HfB ₂ –65 vol％多孔SiC样品（孔隙度为34.5％）是通过在1800°C（加热速率10度/分钟，保持时间15分钟）下对HfB ₂ –（SiO ₂ –C）复合粉末进行反应热压而制得的， 30兆帕。使用高温感应等离子加速器，研究了它们对超音速离解的气流的抗氧化性（实验过程中的热通量从363 W / cm ²变为779 W / cm ²）。在实验过程中对样品表面温度分布的观察表明，与致密样品相比，在较低的热通量和较短的处理时间下，所研究样品的温度从〜1770–1850急剧上升至〜2600°C。 HfB ₂–30 vol％的SiC样品（孔隙度9–11％）。这表明增加HfB ₂ -SiC材料的密度以及增加碳化硅含量会降低抗氧化性。但是，所研究的样品在高焓离解气流中经受了37分钟的暴露（包括在2560–2620°C的表面温度下经过27分钟）而没有被破坏或完全氧化的事实，因此可以将其分配给超高纯空气。高温材料。