Microstructural Design of Si 3 N 4 Based Ceramics
Microstructural Design of Si 3 N 4 Based Ceramics
复制标题
Si 3 N 4 基陶瓷的微观结构设计
DOI：
10.1557/proc-287-3
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
G. Petzow
中科院分区：
文献类型：
--
作者：
M. Hoffmann;G. Petzow
基于只有初始粉末中的β-Si 3 N4颗粒生长的假设，讨论了控制细长Si 3 N4颗粒尺寸和长径比的参数。制备了富α和富β Si 3 N4的混合粉末，研究了其显微组织的变化.通过定量显微结构分析确定Si 3 N4晶粒的长度和纵横比的分布来分析所得的显微结构。随后，分析了烧结条件对晶粒长大的影响以及与力学性能的关系。粗晶材料在热冲击过程中的高威布尔模量和非灾难性失效归因于R曲线行为。最后，研究了烧结助剂对材料力学性能的影响。讨论了添加Yb 2 O3的Si 3 N4陶瓷中基体相和晶界相之间相关系的重要性。结果表明，要使Si 3 N4粉末中的第二相失透，并获得高结晶度，必须考虑粉末中的氧含量。减少添加剂的用量并不一定能改善性能，因为高温强度和蠕变数据会降低。
Parameters controlling the size and aspect ratio of elongated Si 3 N 4 grains are discussed, based on the assumption that only pre-existing β-Si 3 N 4 particles of the starting powder grow. Powder mixtures of α-rich and β-rich Si 3 N 4 were prepared In order to study the microstructural development. The resulting microstructures were analyzed by quantitative microstructural analysis determining the distribution of the length and aspect ratio of the Si 3 N 4 grains. Subsequently, the Influence of the sintering conditions on grain growth was analyzed In relation to mechanical properties. A high Weibull modulus and the non-catastrophic failure during thermal shock of coarse-grained materials Is attributed to an R-curve behaviour. Finally, the influence of sintering additives on the mechanical properties was studied. The Importance of phase relationships between the matrix and the grain boundary phase Is discussed for Si 3 N 4 with Yb 2 O 3 additives. It Is demonstrated that the oxygen content of Si 3 N 4 powder must been taken Into account In order to devitrify defined secondary phases and to achieve a high degree of crystallization. A reduction in the amount of additives does not necessarily Improve the properties as high temperature strength and creep data Indicate.