Preparation of a Porous Cermet SOFC Anode Substrate by Gelcasting of NiO-YSZ Powders

A porous NiO–YSZ substrate for anode‐supported solid oxide fuel cells has been prepared by gelcasting of NiO–YSZ powders using urea–formaldehyde monomers, followed by humidity‐controlled drying, binder removal, and sintering of the gelled bodies. The gelled bodies had sufficient strength to remove even 2‐mm‐thick samples from the mold immediately after gelation. A gelcast NiO–YSZ sample sintered at 1450°C for 2 h showed an open porosity of ∼53 vol%, and the porosity increased to ∼58% upon reduction with hydrogen. Pore sizes measured on the scanning electron microscopy photomicrograph of NiO–YSZ and Ni–YSZ cermet substrates are in the range of 2–5 μm. Urea–formaldehyde polymer, present in a high amount (∼13 wt%) in the gelcast body, acts as a template for pores.