Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s −1 . Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 µm, shell thicknesses ranging from 10 to 50 µm and shell pore diameters ranging from 1 to 10 µm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core–shell multimaterial particles.

Polymer Derived Ceramic Seals for Application in SOFC

Polymer derived ceramic composites have been developed for SOFC seals. The formation and properties of the ceramic composite derived from a mixture with polysiloxane and filler were investigated. In the presence of filler materials such as ZrO2 and AlCo, the thermal properties of the ceramic composite could be controlled. The mixtures with polymethylsiloxane and fillers were prepared and their conversions to ceramic composites by annealing in N2 atmosphere were studied. The microcrystalline composites with filler embedded in a silicon-boron-oxycarbide glass matrix were formed. The thermal expansion behaviors were measured and discussed.