Effect of Heat Treatment in Air on the Surface of a Sintered Ba8Al16Si30-Based Clathrate
Effect of Heat Treatment in Air on the Surface of a Sintered Ba8Al16Si30-Based Clathrate
复制标题
空气中热处理对烧结Ba8Al16Si30基包合物表面的影响
DOI：
10.1007/s11664-013-2887-2
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发表时间：
2014
影响因子：
2.1
通讯作者：
Hiroaki Anno and Ritsuko Shirataki
中科院分区：
文献类型：
--
作者：
Yoji Mine;Daisuke Haraguchi;Takahiro Ideguchi;Nobuaki Horita;Zenji Horita;Kazuki Takashima;Hiroaki Anno and Ritsuko Shirataki
采用电弧熔炼和放电等离子烧结相结合的方法制备了名义成分为Ba8Al15Si31的多晶硅基包合物。在不同温度（873 K、973 K 和 1073 K）和加热时间（0-480 小时）下检查了其在空气中的热稳定性以及空气中热处理对表面的影响，这对于材料在高温下的使用具有实际重要性。在 300–1523 K 范围内空气中的热重分析和差热分析表明，块状的 Ba8Al15Si31 在高温空气中具有相对较好的热稳定性。 X射线衍射测量、扫描电子显微镜、能量色散X射线光谱和X射线光电子能谱表明，通过在空气中热处理，表面形成了一层薄薄的氧化物（可能是铝酸钡，BaAl2O4）。氧化层的厚度随着温度和加热时间的增加而增加。氧化物层的生长可以用扩散机制来很好地解释。氧化的活化能估计约为 201 kJ/mol，与硅的热氧化活化能相当。发现 Ba8Al15Si31 内部的化学成分对于空气中的热处理是稳定的。
A polycrystalline silicon-based clathrate of nominal composition Ba8Al15Si31was prepared by a combination of arc melting and spark plasma sintering. Its thermal stability in air and the effect on the surface of heat treatment in air, which are of practical importance for use of the material at elevated temperatures, were examined for different temperatures (873 K, 973 K, and 1073 K) and heating times (0–480 h). Thermogravimetry and differential thermal analysis in air in the range 300–1523 K indicated that Ba8Al15Si31in the bulk form had relatively good thermal stability in air at high temperatures. X-ray diffraction measurements, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy revealed that a thin layer of oxide (probably a barium aluminate, BaAl2O4) was formed on the surface by heat treatment in air. The thickness of the oxide layer increased with increasing temperature and heating time. Growth of the oxide layer can be explained well in terms of a diffusion mechanism. The activation energy for oxidation was estimated to be approximately 201 kJ/mol, which is comparable with that for thermal oxidation of silicon. The chemical composition of the interior of the Ba8Al15Si31was found to be stable to heat treatment in air.