Processing of Foturan® glass ceramic substrates for micro-solid oxide fuel cells

The microfabrication of Foturan® glass ceramic as a potential substrate material for micro-solid oxide fuel cells (micro-SOFC) was investigated. Foturan® was etched in 10% aqueous hydrofluoric (HF) acid solution at 25 °C with a linear rate of 22 ± 1.7 μm/min to create structures with an aspect ratio of 1:1 in 500 μm-thick Foturan® substrates for micro-SOFCs. The concentration of the HF etchant was found to influence the etching rate, whereas the UV-exposure time creating nuclei in the glass for subsequent crystallization of the amorphous Foturan® material had no significant influence on the etching rates. The surface roughness of the crystallized Foturan® was determined by the crystallite size in the order of 10-15 μm. Free-standing micro-SOFC membranes consisting of a thin film Pt cathode, an yttria-stabilized-zirconia electrolyte and a Pt anode were released by HF etching of the Foturan® substrate. An open-circuit voltage of 0.57 V and a maximum power density of 209 mW/cm2 at 550 °C were achieved.