氧化铝晶片互锁结构/Al2O3-SiO2气凝胶复合材料的微观结构调控及回弹/隔热性能

The requiring properties of the high-temperature insulating/sealing material are lightweight, low thermal conductivity, high mechanical strength and excellent resilience performance. Porous materials constructed by the alumina platelets are promising candidates for high-temperature insulating/sealing application. The core research point of this kind of material is how to improving the structural stability. Focusing on this problem, we have done some research on changing the connecting form between the alumina platelets. In our former work, alumina platelets inter-locked structural material was prepared by the TBA(tert-butyl alcohol)-based gel-casting method. In this material, the alumina platelets are intersected with each other, which is different from the point-connecting in other former reports, resulting in more stable structure. The intersecting area between the alumina platelets acts as supporting node in the material, and the supporting action co-works with the super toughness of the alumina platelets leads to excellent compression-resilience performance. It should be noticed that, the mechanical properties of the material could be directly affected by the alumina platelets’ microstructure feature, however, there is nearly reports focusing on this research point. Besides, it is deemed that the thermal insulating property of the material needs to be modified. Therefore, in this project, we try to tailoring and optimizing the mechanical strength and resilience performance of the alumina platelets inter-locked structure material through controlling the alumina platelets’ microstructure feature by changing the additives’ type and adding amount. Moreover, Al2O3-SiO2 aerogel will be introduced in to heighten the thermal-insulating property of the material. Researches will be done on tailoring the composite’s resilience/insulating properties through controlling its microstructure and on finding the adjustment mechanism between the microstructure feature and the properties of the material. The work in this project is hoped to provide important reference to the research of this kind of high-temperature insulating/sealing material.

高温隔热密封材料的性能要求包括：轻质、低导热率、较高强度及良好回弹特性等。以氧化铝晶片为微观结构组元的多孔材料是较为理想的高温隔热密封材料，对此类材料结构稳定性的提升是核心研究问题。针对该问题，申请人在前期工作中，从优化晶片间连接形式的角度出发，以叔丁醇凝胶注模成型法制备了氧化铝晶片互锁结构材料。该材料中晶片相互交叉连接，区别于以往报道中晶片间的点接触连接形式，因而材料结构更稳定。晶片连接处作为支撑节点，与晶片自身超高韧性结合，使材料获得良好回弹特性。其中，晶片结构特性直接影响材料机械性能，而现有报道中尚缺乏相关研究；另外，该材料隔热性能有待提高。因此，本项目拟通过调节添加剂种类和用量来调控氧化铝晶片结构特性，从而对材料强度及回弹特性进行调控和优化；同时，填充Al2O3-SiO2气凝胶以提高材料隔热性能，考察该复合材料微观结构调控对回弹/隔热性能的调节机制，以期为此类材料研究提供重要参考。

氧化铝多孔陶瓷材料在高温结构陶瓷领域的研究和应用较为广泛。氧化铝晶片互锁结构材料是氧化铝多孔陶瓷材料中的一种，该材料是以刚玉相（α-Al2O3相）氧化铝晶片作为微观结构单元，通过晶片之间相互交叉连接构成的具有各向同性连通孔结构的多孔陶瓷材料。氧化铝晶片是氧化铝晶粒通过发生异向生长形成的片状晶粒，其本身具有优异的断裂韧性，因而以氧化铝晶片构成的互锁结构材料具有较好的力学性能，同时氧化铝晶片所具有的二维平面结构适宜为催化剂提供负载界面。但由于氧化铝晶片互锁结构材料整体的比表面积相对较低，因此就催化剂负载应用而言，该材料的催化剂负载能力有待进一步提高。本项目以氧化铝晶片互锁结构材料作为研究对象，研究过程中，首先对该材料的原料和制备工艺进行了选择和优化，选择环境友好型原料-拟薄水铝石作为主要铝源，同时采用工艺过程较为简便的干压成型法制备得到氧化铝晶片互锁结构材料，并对材料的物相转变过程和微观结构形成过程进行了研究。在此基础上，以氧化铝晶片互锁结构材料作为基体，向其中引入具有高孔隙率、高比表面积及良好耐温性能的Al2O3-SiO2复合气凝胶，制备得到具有适当的孔隙率（63.1%）、密度（1.29g/cm3）、比表面积（57.8m2/g）和压缩强度（~21MPa）的氧化铝晶片互锁结构/Al2O3-SiO2气凝胶复合材料，Al2O3-SiO2复合气凝胶的引入提升了材料的催化剂负载能力，该材料能够被用于高温反应中催化剂负载。另外，在研究过程中，以拓展氧化铝晶片互锁结构材料在光催化降解方面的应用为研究目的，采用以拟薄水铝石为主要铝源并以塑性成型法制备的氧化铝晶片互锁结构材料作为基体，向其中引入具有光催化降解性能的TiO2气凝胶，制备得到氧化铝晶片互锁结构/TiO2气凝胶复合材料，同时考察了该材料对于有机染料-罗丹明B的光催化降解性能和材料的可重复利用情况。希望本项目的研究工作能够为多孔陶瓷材料领域的相关研究提供具有一定意义的参考。