Controlled Porosity Materials: Before, During and After Sintering

9500282 Gerhardt拟议研究的目标是确定孔微结构和热处理之间的关系，以创建可控孔隙率材料。为完成这一任务，将开展以下工作：(1)制备平均孔径和多分散度均具有系统变化的微观结构的胶体二氧化硅/可溶性硅酸盐整体(S)。孔结构将通过化学处理中的修改来进行工程设计。(2)利用显微镜(光学显微镜和电子显微镜)和几种不同的测量技术相结合的方法，在烧结前充分表征前驱体材料的微观结构。(3)通过对等温烧结态和淬火态样品的孔径、形状和分布的测量，定量地表征了非原位显微组织的演变。利用NIST反应堆独特的小角中子散射炉，将烧结研究扩展到原位等温烧结和同时散射实验。(4)利用计算机模拟和模拟来帮助阐明导致所观察到的孔结构演化的微观结构机制。许多工程应用，如超级绝缘体、过滤器和传感器，都需要多孔材料。了解多孔材料在烧结过程中的孔结构演变对于制备和控制多孔材料的最终微观结构是至关重要的。本项目所研究的材料提供了一个值得注意的机会，可以定制绝缘目的的导热系数、传感设备的介电常数和多孔结构陶瓷的弹性模数。

9500282 Gerhardt The objective of the proposed research is to determine the relationship between pore microstructure and thermal treatment for the creation of controlled porosity materials. To accomplish that task the following activities will be carried out: (1) Fabricate colloidal silica/soluble silicate monoliths having systematically varied microstructures with respect to both average pore size(s) and polydispersity. The pore structure will be engineered by modifications in chemical processing. (2) Characterize the microstructure of the precursor materials fully before sintering using a combination of microscopy (optical, and electron microscopy), and several different measurement techniques. (3) Quantitatively characterize the evolution of the microstructure ex-situ by means of pore size, shape and distribution measurements on isothermally sintered and quenched samples. Extend the sintering studies to in-situ isothermal sintering and simultaneous scattering experiments by means of a unique small angle neutron scattering furnace at the NIST reactor. (4) Utilize computer simulation and modeling to help elucidate the microstructural mechanisms responsible for the observed pore structure evolution. %%% Numerous engineering applications such as superinsulators, filters, and sensors require porous materials. Understand- ing the pore structure evolution during sintering is essential for the fabrication and control of the final microstructure in porous materials. Materials such as those studied in this project offer a notable opportunity, to tailor thermal conductivity for insulating purposes, dielectric constant for sensing devices and elastic modulus for porous structural ceramics.