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Creep deformation behavior during densification of ZrB 2 -SiBCN ceramics with ZrO 2 additive
Journal of Advanced Ceramics ( IF 18.6 ) Pub Date : 2020-06-19 , DOI: 10.1007/s40145-020-0393-6
Bo Feng , Zhenhang Wang , Yunhao Fan , Jinghua Gu , Yue Zhang

ZrB2-SiBCN ceramics with ZrO2 additive are hot-pressed under a constant applied pressure. The densification behavior of the composites is studied in a view of creep deformation by means of the Bernard-Granger and Guizard model. With determination of the stress exponent (n) and the apparent activation energy (Qd), the specific deformation mechanisms controlling densification are supposed. Within lower temperature ranges of 1300–1400 °C, the operative mechanism is considered to be grain boundary sliding accommodated by atom diffusion of the polymer-derived SiBCN (n = 1, Qd = 123±5 kJ/mol) and by viscous flow of the amorphous SiBCN (n = 2, Qd = 249±5 kJ/mol). At higher temperatures, the controlling mechanism transforms to lattice or intra-granular diffusion creep (n = 3–5) due to gradual consumption of the amorphous phase. It is suggested that diffusion of oxygen ions inside ZrO2 into the amorphous SiBCN decreases the viscosity, modifies the fluidity, and contributes to the grain boundary mobility.



中文翻译:

ZrO 2添加剂在ZrB 2 -SiBCN陶瓷致密化过程中的蠕变变形行为

具有ZrO 2添加剂的ZrB 2 -SiBCN陶瓷在恒定的施加压力下进行热压。借助蠕变变形,利用Bernard-Granger和Guizard模型研究了复合材料的致密化行为。通过确定应力指数(n)和表观活化能(Q d),推测出控制致密化的特定变形机制。在1300–1400°C的较低温度范围内,其作用机理被认为是由聚合物衍生的SiBCN的原子扩散(n = 1,Q d = 123±5 kJ / mol)和粘滞流动引起的晶界滑动。非晶SiBCN(n= 2,Q d = 249±5 kJ / mol)。在更高的温度下,由于非晶相的逐渐消耗,控制机制转变为晶格或晶内扩散蠕变(n = 3-5)。认为ZrO 2内部的氧离子向非晶态SiBCN的扩散降低了粘度,改变了流动性,并有助于晶界迁移率。

更新日期:2020-06-19
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