非晶Si3N4氧化晶化法制备Si2N2O透波陶瓷及其晶化-致密化耦合机制

项目名称： 非晶Si3N4氧化晶化法制备Si2N2O透波陶瓷及其晶化-致密化耦合机制

项目编号： No.51272206

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 王红洁

作者单位： 西安交通大学

项目金额： 80万元

中文摘要： 石英类材料和多孔氮化硅是针对高速飞行器天线罩/窗应用的两类主流高温透波材料，但存在吸潮、抗机械冲击及热冲击性能差等问题。近期研究发现Si2N2O是综合性能更优的高温透波候选材料。但Si2N2O高温易分解，难以制备高纯致密的Si2N2O陶瓷。本项目提出非晶氧化晶化法低温制备Si2N2O陶瓷的新思路，即以非晶Si3N4为原料，控制原料中氧含量、气氛中微氧分压，低温合成Si2N2O相；SPS超快烧结，动力学抑制其高温分解。无需添加烧结助剂即可低温实现致密化，有效避免材料高温性能衰减。该过程涉及Si3N4到Si2N2O、非晶到多晶的转变、元素的耦合扩散与原位反应等复杂变化，目前对其机理不清楚。本研究力图阐明影响非晶Si3N4结晶过程及晶型转变的主要因素、Si2N2O的合成反应及相演变机理、晶化与致密化过程耦合机制等关键科学问题，建立一种制备高纯Si2N2O陶瓷的新方法，获得性能更优的高温透波材料

中文关键词： 透波陶瓷；氧氮化硅；非晶纳米氮化硅；氧化；晶化

英文摘要： Quartz-based and porous silicon nitride material are two major categories of high-temperature wave-transparent materials for high speed aircraft radomes though the moisture absorption, poor mechanical impact and thermal shock resistance are their disadvantages. Recent studies show that Si2N2O is an promising candidate material for high-temperature wave-transparent application, for its better performance in general. However, it is difficult to produce fully dense Si2N2O ceramics because Si2N2O tends to decompose at the required sintering temperature. In this research, the novel process of preparation of Si2N2O ceramics by amorphous oxidation crystallization is proposed, that is, amorphous silicon nitride powder was used to synthesize Si2N2O phase at a low temperature by controlling oxygen in raw material and micro-oxygen pressure in sintering atmosphere, followed by SPS (spark plasma sintering) by which the decomposition of Si2N2O is inhibited at high temperature. The densification of Si2N2O ceramic can be achieved in low temperature without sintering additives and, therefore, the decrease of high-temperature properties can be prevented. Various and complex changes are involved in this process including Si3N4 to Si2N2O transformation, amorphous to polycrystalline formation, mass coupling diffusion and in situ re

英文关键词： wave transparent ceramic；Si2N2O；amorphous nano-Si3N4 powders；oxidation；crystallization