Oxidation of ZrB2 powder in the temperature range of 650–800 °C
Oxidation of ZrB2 powder in the temperature range of 650–800 °C
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DOI：
10.1016/j.jallcom.2008.04.006
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发表时间：
2009-03
影响因子：
6.2
通讯作者：
Weiming Guo;Guo‐Jun Zhang;Y. Kan;Pei-ling Wang
中科院分区：
文献类型：
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作者：
Weiming Guo;Guo‐Jun Zhang;Y. Kan;Pei-ling Wang
采用热重分析法（TGA）在650-800°C的流动空气中对ZrB 2粉末进行了等温氧化。采用X射线衍射（XRD）和扫描电子显微镜（SEM）分别研究了ZrB 2粉末在700°C下氧化不同时间后的物相特征和形貌的演变。多重律模型对热重曲线的拟合表明，ZrB 2粉末在空气中的氧化遵循准线性动力学，并根据拟合结果得到了ZrB 2粉末的氧化机理。在700°C下，ZrB 2粉末与氧的反应产物为亚稳的四元ZrO 2，随着氧化，四元相转变为单斜相。ZrB 2粉末的氧化与表面微裂纹的形成有关，这归因于ZrB 2氧化为四方相ZrO 2和四方相到单斜相ZrO 2的相变导致的体积膨胀。在氧化的最后阶段，每个ZrB 2颗粒破碎成碎片。
The isothermal oxidation of ZrB2powder was carried out in the range of 650–800°C in a flowing air using thermogravimetric analysis (TGA). The evolution of the phase characterization and morphology of ZrB2powder oxidized at 700°C for varying durations was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The excellent fit of TG curves by multiple-law model suggests that the oxidation of ZrB2powder in air follows para-linear kinetics, and based on the fitted results, oxidation mechanisms can also be obtained. The reaction product of ZrB2powder with oxygen is metastable tetragonal ZrO2at 700°C, and the tetragonal phase transforms to the monoclinic phase with oxidation. The oxidation of ZrB2powder is associated with surface microcrack formation, which is attributed to volume expansion resulting from oxidation of ZrB2to tetragonal ZrO2and tetragonal-to-monoclinic phase transformation of ZrO2. In the last stage of oxidation, each ZrB2particle breaks into fragments.