Structure-property relationships of hierarchically structured silica monoliths as a model system for innovative inorganic thermal insulating materials

分层结构二氧化硅整体的结构-性能关系作为创新无机隔热材料的模型系统

• 批准号: 461861936
• 负责人: Professor Dr.-Ing. Frank Dehn
• 金额: --
• 依托单位: Bayerisches Zentrum für Angewandte Energieforschung e.V. (ZAE Bayern)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/461861936?language=en
• 关键词: Structure; property; relationships; hierarchically; structured

Insulating buildings thermally is a key to reduce the energy consumption. In this regard, recent research is focusing on non-fibrous, amorphous SiO2-based insulating materials. The microstructure and therefore also the properties of these materials can be tailored by adjusting the synthesis parameters. However, there are two conflicting goals, as increasing porosity decreases thermal conductivity on the one hand, but also decreases mechanical resistance. Hierarchically structured silica monoliths showing bimodal porous structures have been already tailored to fulfill either one goal or the other, but tailoring materials with an optimized combination of both opposing parameters has not been done yet. For this task suitable model systems and systematic studies of the influence of porosity, pore size and their structural arrangement on thermal conductivity and mechanical resistance of these types of material are yet missing.The main goal of this project is therefore to systematically investigate for the first time the complex relationships between pore size, porosity, pore structure (monomodal or bimodal) and thermal conductivity as well as mechanical resistance of self-supporting SiO2-based monolithic materials with open-celled porous structure, to model these properties and finally to develop a synthetic route to implement the insights gained. For that to happen, different synthetic methods are used to produce three different silica model systems: (i) monoliths made of porous glass showing monomodal pore distribution, (ii) aerogels with systematically varied pore size and (iii) sol-gel monoliths with bimodal porosity. The experimental methods planned for characterization are for structural analysis mercury intrusion, micro-tomography (µXCT), small angle scattering (SAXS) and electron microscopy (SEM, FIB-SEM, STEM). The thermal transport properties are quantified by the hot wire method. The mechanical characteristics on different structural levels are determined by nanoindentation and nitrogen sorption with in-situ dilatometry, as well as by various mechanical testing. These experimental methods are designed to provide the input data for simulations using the finite-volume method to systematically investigate the relationship between structures and properties. Finally, the simulated structures with optimized tailored properties will be synthesized to validate the results of the simulations. For the first time experts in characterizing the porous structure, the thermal conductivity and the mechanical resistance as well as experts for the synthesis will join together within this synergetic collaboration to study the fundamental relationship between structure and properties of silica monoliths. The insights gained can be used to develop innovative tailored inorganic insulating materials and in addition can act as a starting point to characterize more complex porous construction materials such as concrete and bricks.

建筑物隔热是降低能耗的关键。在这方面，最近的研究集中在非纤维状、无定形SiO2基绝缘材料上。这些材料的微观结构和性能可以通过调整合成参数来定制。然而，存在两个相互冲突的目标，因为增加孔隙率一方面降低热导率，但也降低机械阻力。显示双峰多孔结构的分级结构的二氧化硅整料已经被定制以满足一个目标或另一个目标，但是还没有完成具有两个相反参数的优化组合的定制材料。对于这一任务，还缺少合适的模型系统和系统研究孔隙率、孔隙尺寸及其结构排列对这些类型材料的热导率和机械阻力的影响。因此，本项目的主要目标是首次系统地研究孔隙尺寸、孔隙率、孔隙尺寸及其结构排列之间的复杂关系。孔结构（单峰或双峰）和热导率以及具有开孔多孔结构的自支撑SiO2基整体材料的机械阻力，以模拟这些性能，并最终开发出一种合成路线来实现所获得的见解。为此，使用不同的合成方法来产生三种不同的二氧化硅模型系统：（i）由多孔玻璃制成的显示单峰孔分布的整料，（ii）具有系统变化的孔径的气凝胶和（iii）具有双峰孔隙率的溶胶-凝胶整料。计划用于表征的实验方法包括结构分析汞侵入、显微断层扫描（µXCT）、小角散射（SAXS）和电子显微镜（SEM、FIB-SEM、STEM）。热传输性能的量化热线法。不同结构水平上的机械特性通过纳米压痕和氮气吸附与原位硬度计以及各种机械测试来确定。这些实验方法的目的是提供输入数据的模拟使用有限体积法系统地调查结构和性能之间的关系。最后，将合成具有优化的定制特性的模拟结构以验证模拟结果。这是第一次，表征多孔结构，热导率和机械阻力的专家以及合成专家将在这种协同合作中联合起来，研究二氧化硅整料的结构和性能之间的基本关系。所获得的见解可用于开发创新的定制无机绝缘材料，此外还可作为表征混凝土和砖等更复杂多孔建筑材料的起点。