注凝成型原位自生氮化硅助剂熔融石英陶瓷致密化机理的研究

Starting with authigenic silicon-nitride sintering additives, through studying green body and sintering densification, the solution of fused silica ceramic's lower sintering compactness which prepared by gel-casting technology was explored in this project. Using reaction thermodynamics and dynamics, the sucrose pyrolysis and carbothermal reduction authigenic silicon-nitride additives reaction process were analyized. Meanwhile, the influence law of multivariate conditions on conversion of situ generation additives and powder microstructure in preparation process were also explored , and the accurate and controllable theoretical model of authigenic silicon-nitride additives was constructed. Through note cemented type technology theory, the relative physical chemical changes of quartz ceramic body's through the preparation process was revealed, and high densification mechanism of green body was clarified. Combined with fitting calculation of JMA equation, Arrhenius equation and Augis-Bennett equation, crystallization kinetics of sintering system was studied. Using Frenkel sintering formula, the mathematical mode of sintering activation energy of this system was constructed, and the densification mechanism under inhibition crystallization premise was explored. This project offered new thinking in injection setting molding Solar fused silica ceramic's high homogeneous densification , the research results had strong theoretical and practical value.

本项目拟从原位自生氮化硅烧结助剂，生坯与烧结致密化等方面入手，探讨解决注凝成型技术制备的石英陶瓷制品烧结致密性不高等问题。采用反应热力学与动力学等方法分析蔗糖热解与碳热还原氮化自生氮化硅助剂反应转变过程，探索制备过程中多因素条件对原位生成助剂转化率及粉体微观结构影响规律，构建自生氮化硅助剂精确可控理论模型；通过注凝成型技术理论，揭示石英陶瓷生坯整个制备过程相关的物理化学变化过程，明晰生坯高致密化机制；结合JMA方程、Arrhenius方程与Augis-Bennett方程拟合计算，研究该体系烧结的晶化动力学，利用Frenkel烧结公式，构建该体系烧结活化能的数学模型，进而探索在抑制析晶前提下致密化机理。本项目研究为解决注凝成型太阳能级熔融石英陶瓷高均质致密化关键问题提供新的思路，研究结果具有很强的理论应用与工程实用价值。

以解决注凝成型工艺成型熔融石英陶瓷制品的低密度性为出发点，围绕注凝成型、原位自生、微波烧结工艺进行研究，确定了最佳注凝成型的工艺条件。采用反应热力学与动力学等方法分析，探索原料制备过程中多因素条件对原位自生引入助剂的转化率及粉体微观结构影响规律，并探索各因素条件对坯体成型性能影响的规律，从而实现生坯高度致密化。结合粘度测试、Zeta电位测试、X射线衍射分析、X射线光电子能谱、红外光谱分析、电镜扫描、强度测试等表征及检测手段进行性能分析。制备的样品达到了预期对试样的要求目标，但将其致密化的研究投入到注凝成型大尺寸化市场的应用中，还有许多需要进一步研究和改进的地方。