High-temperature oxidation behavior of high-purity α-, β-, and mixed silicon nitride ceramics
High-temperature oxidation behavior of high-purity α-, β-, and mixed silicon nitride ceramics
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DOI：
10.1111/j.1151-2916.2002.tb00101.x
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发表时间：
2004-12
影响因子：
3.9
通讯作者：
M. Backhaus-Ricoult;V. Guérin;A. Huntz;V. Urbanovich
中科院分区：
文献类型：
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作者：
M. Backhaus-Ricoult;V. Guérin;A. Huntz;V. Urbanovich
研究了无添加剂的α-、β-和混合氮化硅陶瓷的高温氧化行为、显微结构演变和氧化动力学。陶瓷的氧化速率取决于同素异形体的比例;富含α相的陶瓷具有最佳的抗氧化性。氧化动力学的变化直接关系到平均晶粒尺寸和玻璃分布在氧化皮。在Si 3 N4相在氧化前沿溶解之前，其氧含量并入Si 3 N4相中影响局部玻璃组合物，从而产生玻璃相内SiO2微晶的成核和生长速率以及最终的氧化皮微观结构，这取决于并入的氧含量。对于α-多晶型物，发现动态氧溶解度保持可忽略不计;因此，富氮玻璃在氧化前沿形成，这促进失透并产生具有小晶粒尺寸和薄晶间玻璃膜的规模。观察到β-Si 3 N4在氧化时形成富氧固溶体，其与氮氧化硅或富氧玻璃接触。后者的方石英成核缓慢，产生粗晶氧化皮，晶间玻璃膜厚。
High-temperature oxidation behavior, microstructural evolution, and oxidation kinetics of additive-free α-, β-, and mixed silicon nitride ceramics is investigated. The oxidation rate of the ceramics depends on the allotropic ratio; best oxidation resistance is achieved for ceramics rich in α-phase. Variations in the oxidation kinetics are directly related to average grain size and glass distribution in the oxidation scale. The oxygen contents incorporated into the Si3N4 phase before its dissolution at the oxidation front affects the local glass composition and thereby yields nucleation and growth rates of SiO2 crystallites within the glass phase and a final oxidation scale microstructure, which depend on the incorporated oxygen contents. For the α-polymorph, the dynamic oxygen solubility is found to remain negligible; therefore, a nitrogen-rich glass forms at the oxidation front, which promotes devitrification and yields a scale with small grain size and thin intergranular glass films. β-Si3N4 is observed to form oxygen-rich solid solutions on oxidation, which are in contact with silicon oxynitride or oxygen-rich glass. Nucleation of cristobalite in the latter is sluggish, yielding coarse-grained oxidation scales with thick intergranular glass film.