Experimental study on the oxidation of MgB2 in air at high temperature
Experimental study on the oxidation of MgB2 in air at high temperature
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DOI：
10.1088/0953-2048/16/5/306
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发表时间：
2003-03
影响因子：
3.6
通讯作者：
Delin Yang;Hongwei Sun;Hongxia Lu;Yiqun Guo;Xinjian Li;Xing Hu
中科院分区：
文献类型：
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作者：
Delin Yang;Hongwei Sun;Hongxia Lu;Yiqun Guo;Xinjian Li;Xing Hu
采用热重分析、X射线衍射和扫描电镜结合能谱研究了MgB 2在室温至1000 °C空气条件下的氧化过程。实验表明，在400 ℃左右开始出现明显的氧化过程，当温度超过700 ℃时，氧化过程变得非常强烈。X射线衍射表明，在高温下长时间氧化后，MgB 2中的大部分镁变成MgO。显微组织和成分分析表明，MgB 2的氧化是一个复杂的过程，伴随着硼和镁的蒸发和MgO的形成。在氧化过程中，由于蒸发的镁与氧的反应，也出现了直径在纳米级的长MgO晶须，主要在晶粒表面。采用基于Arrhenius方程的Freeman-Carroll方法估算了MgB 2的氧化活化能。结果表明，在强氧化温度范围内，活化能约为70-90 kJ mol-1。
Oxidation of MgB2 under air conditions of room temperature to 1000 °C was studied by thermogravimetry, x-ray diffraction and scanning electron microscopy equipped with energy dispersion spectrum. The experiment shows that the obvious oxidation process begins at about 400 °C and becomes very strong when the temperature reaches beyond 700 °C. X-ray diffraction shows that after oxidation for a long time at high temperature, most of the magnesium in MgB2 becomes MgO. The analyses of the microstructure and components show that the oxidation of MgB2 is a very complex process accompanying the evaporation of boron and magnesium and the formation of MgO. Long MgO whiskers with diameters in the nanometre scale also appear, mostly on the grain surface, in the oxidation process due to the reaction of evaporated magnesium with oxygen. The oxidation activation energy of MgB2 is estimated by using the Freeman–Carroll method based on the Arrhenius equation. It is shown that in the range of strong oxidation temperature the activation energy is about 70–90 kJ mol−1.