The thermal stability in air of hot-pressed diboride matrix composites for uses at ultra-high temperatures
The thermal stability in air of hot-pressed diboride matrix composites for uses at ultra-high temperatures
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DOI：
10.1016/j.corsci.2004.09.019
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发表时间：
2005-08
影响因子：
8.3
通讯作者：
F. Monteverde
中科院分区：
文献类型：
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作者：
F. Monteverde
研究了两种含19.5% v/o SiC和3 v/o HfN（助烧剂）的热压二硼化物基复合材料在1600℃高温下的抗氧化性能。二硼化物基体为hfb2或ZrB2/ hfb2混合物（体积比≈1）。这两种材料在1600°C下反复加热-冷却循环，并在1450°C的干燥空气中暴露20小时。适度的重量增加和有限的腐蚀深度突出了相当好的热稳定性。在1450℃的热重测试中，两种复合材料的氧化动力学均符合准线性规律。SiC颗粒的引入对抗氧化性能有明显的好处。其中一种氧化产物是硼硅酸盐玻璃，它密封了孔隙并涂覆在暴露的表面上，极大地限制了氧气向内部氧化物/二硼化物界面的向内运输。
The resistance to oxidation in ambient air at a temperature up to 1600°C of two hot-pressed diborides matrix composites, both containing 19.5% v/o SiC and 3 v/o HfN (as sintering aid), was investigated. The diboride matrix was based on HfB2or a ZrB2/HfB2mixture (volume ratio ≈1). Both the materials were subjected to repeated heating-cooling cycles at 1600°C, and a 20h exposure at 1450°C in flowing dry air. Modest weight gains and limited corrosion depths highlighted a rather good thermal stability. In accordance with the thermo-gravimetric test at 1450°C, the oxidation kinetics for both the composites superbly fit a para-linear law. The introduction of the SiC particles provided tangible benefits for the resistance to oxidation. One of the oxidation products, a borosilicate glass, sealed pores and coated the exposed faces, greatly limiting the inward transport of oxygen towards the internal oxide/diboride interfaces.