Nanoscale and Energy Materials
Kathy Lu
In this presentation, two research topics will be covered. One is nanoparticle colloidal
dispersion and freeze casting. The other is solid oxide fuel cell seal.
Liquid processing has the most promise for nanostructured bulk material forming. Our
efforts have been focused on understanding and developing a water-based system to
create stable nanoparticle suspensions of high solids loading. With this, a new forming
process for nanostructured materials, freeze casting, has been studied with the objective
to bridge multiple length scales. This approach has the desired ability to maintain
dispersed state of high solids loading suspension with different aspect ratio species, such
as nanoparticles with a range of size distribution and nanoparticle-carbon nanotube
composites. The process can make complex, near-net shape, and fine features with high
green density. This talk will discuss the necessary conditions for producing high solids
loading nanoparticle suspensions, followed by analyzing the microstructure evolution of
nanoparticle suspension during freeze casting. We will also examine the characteristics of
the freeze cast green components and ability of forming fine features by such technique.
Glass and glass-ceramics are promising candidates for planner solid oxide
fuel/electrolyzer cell seals. However, thermophysical property match with other cell
components and thermal stability of the seals are challenging problems to overcome. Seal
can react with other cell components and present poor thermal stability, low thermal
expansion coefficient, and low glass transition temperature. We have found a SrO-La2O3Al2O3-B2O3 –SiO2 based glass system that offers the rare possibility of combining all the
desired properties of a solid oxide fuel cell seal. The compositions are composed of
mostly the existing species in other cell components. The new seal demonstrates long
term thermal stability, high thermal expansion coefficient, and high glass transition
temperature. In this presentation, the effect of the new glass compositions on
thermophysical properties, phase evolution, and thermal stability will be discussed.