Fabrication and characterization of ZrB2-SiC ceramic electrodes coated with a proton conducting, SiO2-rich glass layer

3.5 mu m thin layers of dense, crack-free, proton conducting. SiO2-rich glass have been developed on ZrB2-SiC ceramic composites, by thermal oxidation at 1400 degrees C for 30 min in air. A conductivity of 2 mS cm(-1) at 25 degrees C was found, as measured by AC impedance and steady-state voltammetry, and was estimated at ca. 2 x 10(-2) S cm(-1) at 80 degrees C. A striking behaviour of the oxidized ZrB2-SiC composites is also pointed out: underneath the glass layer, there is a porous layer rich in electronic conductive ZrB2, without well-defined interface between them, i.e., exhibiting a composition gradient in oxygen. In other words, protonic half-fuel cells could be fabricated under such conditions, for future use in hydrogen or direct alcohol fuel cells. (C) 2011 Elsevier Ltd. All rights reserved.