Influence of the Interfacial Properties on the Microstructural Development and Properties of Silicon Nitride Ceramics
Influence of the Interfacial Properties on the Microstructural Development and Properties of Silicon Nitride Ceramics
复制标题
界面性质对氮化硅陶瓷微观结构发展和性能的影响
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
R. M. Cannon
中科院分区：
文献类型：
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作者：
Michael J. Hoffmann;H. Gu;R. M. Cannon
研究了M-Si-Al-O-N(M=Yb，Gd，ND，La，Y)和M-Si-Mg-O-N(M=Lu，Sm，La，Sc，Y)两个过饱和氮氧化物玻璃系统中烧结助剂体系对氮化硅晶体生长各向异性的影响。这种玻璃含有较低的颗粒体积分数，为研究颗粒生长提供了无碰撞的可能性。两种体系的长径比均随稀土元素阳离子半径的增大而增大。从离子半径来看，Sc基玻璃和Y基玻璃的长宽比都比预期的要高。大块玻璃和凝聚颗粒之间的晶界膜的分析透射电子显微镜揭示了化学成分的不同。与体相成分相比，较大的稀土阳离子在薄膜中富集，较小的稀土阳离子则被亏损。较大阳离子的富集层可以看作是一层吸附层，它减缓了棱柱面的生长速度。具有较小阳离子(Yb，Gd)的玻璃系统显示出棱镜面的显著生长，并在颗粒的外部区域形成Sialon。决定断裂韧性的界面强度随阳离子半径的减小而增大，但这种影响主要归因于Sialon的形成，而不是阳离子本身。
The influence of the sintering additive system on the grain growth anisotropy of silicon nitride has been studied in the two supersaturated oxynitride glass systems M-Si-Al-O-N (where M = Yb, Gd, Nd, La, and Y) and M-Si-Mg-O-N (where M = Lu, Sm, La, Sc and Y). The glasses contained a low volume fraction of grains and offer the possibility to study grain growth without impingement. Both systems show an increase of the aspect ratio with an increasing cation radius of the rare earth elements. The aspect ratios for the Sc- and Y-based glasses are higher than expected from the ionic radius. Analytical transmission electron microscopy of the bulk glass and grain boundary film between flocculated particles reveals a difference in chemical composition. The larger rare earth cations are enriched in the film and the smaller ones are depleted compared to the bulk composition. The enrichment of the larger cations can be considered as an adsorption layer which reduces the growth rate of the prism planes. Glass systems with smaller cations (Yb, Gd) reveal a pronounced growth of the prism planes and sialon is formed in the outer region of the grains. The interfacial strength which determines the fracture toughness increases with a decreasing cation radius, but the effect is mainly attributed to the sialon formation rather than by the cation itself.