新型振荡压力烧结制备超高强度氮化硅基复合材料及机理研究

Aiming at increasing requirements for Si3N4 ceramics in mechanical performances such as strength, toughness and reliability, reinforcing phases and a novel oscillatory pressure sintering (OPS) will be adopted during sintering of Si3N4 ceramics. Compared with traditional static sintering, OPS with controllable pressure value and frequency during sintering could provide higher sintering driving force. In this project, the densification, grain growth, defect removal, strength and toughness of Si3N4 composite will be investigated by adding multi-additives such as Al2O3-Y2O3-La2O3 to Si3N4 with carbon nano-tubes and graphenes as reinforcing phases under OPS process. The influence of pressure value and frequency on the mechanical properties will be investigated by adopting measuring-displacement system to obtain densification route combining the variation of grain size. The microstructure and phase transition during sintering will be analysized. Meanwhile, the toughening mechanism and oscillatory sintering mechanism of experimental system will be discussed. The project implementation could provide theoretical basis for preparing advanced Si3N4 composites with high density, fine grains, little defects and excellent strength.

本项目针对极端环境对氮化硅陶瓷材料强度、韧性和可靠性等方面要求越来越高，拟在氮化硅陶瓷材料烧结过程中添加增强相并采用新型振荡压力烧结技术。与传统的热压烧结等静态烧结技术相比，振荡压力烧结可施加振幅与频率可控的振荡压力，提供较高的烧结驱动力。本项目以氮化硅为研究对象，采用碳纳米管、石墨烯等为增强相，添加Al2O3-Y2O3-La2O3等复合烧结助剂，开展振荡压力烧结氮化硅基复合材料致密化进程、晶粒生长、缺陷消除、强韧化等方面的研究。采用实时位移检测系统测量粉体的致密化曲线，结合材料的晶粒尺寸变化，研究振荡压力振幅、频率等对氮化硅基复合材料力学性能的影响，分析微观结构以及烧结过程中物相的演变，并对实验体系的强韧化机理和振荡压力烧结机理进行探讨。本项目的实施，将为高致密度、细晶粒、低缺陷、强度韧性优异的氮化硅基复合材料的制备提供理论依据。

本项目针对极端环境对氮化硅陶瓷材料强度、韧性和可靠性等方面要求越来越高，拟在氮化硅陶瓷材料烧结过程中添加增强相并采用新型振荡压力烧结技术。与传统的热压烧结等静态烧结技术相比，振荡压力烧结可施加振幅与频率可控的振荡压力，提供较高的烧结驱动力。本项目以氮化硅为研究对象，采用碳纳米管、石墨烯等为增强相，添加MgO-Al2O3-Y2O3等复合烧结助剂，开展振荡压力烧结氮化硅基复合材料致密化进程、晶粒生长、缺陷消除、强韧化等方面的的研究。研究了烧结温度、恒定压力、振荡压力、保温时间等对氮化硅基复合材料力学性能的影响，分析微观结构以及物相的不同，并对实验体系的强韧化机理、高温稳定性和振荡压力烧结机理进行探讨。本项目的实施，将为高致密度、细晶粒、低缺陷、强度韧性优异的氮化硅基复合材料的制备提供理论依据。