High-Temperature Oxidation Behavior of Filled Skutterudites YbyCo4Sb12
High-Temperature Oxidation Behavior of Filled Skutterudites YbyCo4Sb12
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DOI：
10.1007/s11664-012-2038-1
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发表时间：
2012-04
影响因子：
2.1
通讯作者：
Xugui Xia;P. Qiu;Xun Shi;Xiaoya Li;Xiangyang Huang;Lidong Chen
中科院分区：
文献类型：
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作者：
Xugui Xia;P. Qiu;Xun Shi;Xiaoya Li;Xiangyang Huang;Lidong Chen
研究了填充方钴矿YbyCo4Sb12的氧化行为。YbyCo_4Sb_（12）的氧化过程分为两个阶段。在第一阶段中，由于高温下氧与方钴矿之间的反应，在表面上逐渐形成致密的氧化物层。在第二阶段，由于氧化层与方钴矿基体之间的热膨胀系数不匹配，氧化层中产生微裂纹，为外部氧和内部Sb提供了传输通道，加速了氧化过程。整个氧化过程可以通过致密层形成→应力释放→微裂纹形成→自修复→致密层形成的重复循环来描述。采用多升温速率热重法测得的填充方钴矿的氧化活化能低于未填充CoSb 3的氧化活化能。此外，还发现，随着Yb填充分数的增加，氧化激活能单调下降。我们的研究结果表明，防止氧化是必要的应用填充方钴矿。
The oxidation behavior of filled skutterudites YbyCo4Sb12was investigated. The overall oxidation of YbyCo4Sb12consists of two stages. In the first stage, densified oxide layers form on the surface gradually due to the reaction between oxygen and skutterudite at high temperature. In the second stage, microcracks evolve in the oxide layers because of mismatch of coefficient of thermal expansion between the oxide layer and skutterudite matrix, which accelerates the oxidation by providing transport paths for both outside oxygen and inside Sb. The overall oxidation process can be described through the repetitive cycle: dense layer formation → stress release → microcrack formation → self-repair → dense layer formation. The oxidation activation energy of filled skutterudites determined using thermogravimetry method with multi-heating rates is lower than that of unfilled CoSb3. Moreover, it was found that, with increasing Yb filling fraction, the oxidation activation energy decreases monotonically. Our results suggest that protection against oxidation is necessary for application of filled skutterudites.