Zirconium Carbide Oxidation: Maltese Cross Formation and Interface Characterization
Zirconium Carbide Oxidation: Maltese Cross Formation and Interface Characterization
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DOI：
10.1007/s11085-016-9672-6
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发表时间：
2017-10
影响因子：
2.2
通讯作者：
C. Gasparrini;R. Podor;D. Horlait;R. Chater;William E Lee
中科院分区：
文献类型：
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作者：
C. Gasparrini;R. Podor;D. Horlait;R. Chater;William E Lee
使用原位技术：HT-ESEM 研究了致密热压 ZrC 样品在 1073 至 1473 K 范围内的氧化情况。在氧化过程中对长方体样品的表面、边缘和角落进行监测，以了解裂纹形成和扩展对氧化物马耳他十字形状发展的影响。氧化机制包括三个步骤：(1) 样品边缘分层，(2) 在拐角处形成裂纹，(3) 裂纹向内核扩展并形成平行于界面的微裂纹，从而增加可接触的表面积，随后体积急剧膨胀。发现微裂纹图案是重复的，就像发生了界面的循环脱粘一样。通过 TEM 和 HRTEM 对界面进行表征，发现 ZrC 和 ZrO2 之间的界面由 2 µm 厚的无定形碳基体组成，其中嵌入了 ZrO2 纳米晶体。
Oxidation of dense hot-pressed ZrC specimens from 1073 to 1473 K was investigated using an in situ technique: HT-ESEM. Cuboid specimens were monitored on the surface and on edges and corners during oxidation in order to understand the influence of crack formation and propagation on the Maltese cross shape development of the oxide. The oxidation mechanism comprised three steps: (1) delamination of sample edges, (2) crack formation at corners and (3) crack propagation towards the inner core and formation of microcracks parallel to the interface that increase the accessible surface area followed by a drastic volume expansion. The microcrack pattern is found to be repetitive as if a cyclic debonding of the interface occurred. Characterization of the interface by TEM and HRTEM revealed the interface between ZrC and ZrO2to comprise a 2 µm thick amorphous carbon matrix with ZrO2nanocrystals embedded in it.