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.
