Fabrication and Characterization of Thin and Dense Electrolyte‐Coated Anode Tube Using Thermoplastic Coextrusion

Anode tubes coated with thin and dense electrolyte layers were fabricated by thermoplastic coextrusion, using a nickel oxide (NiO)–yttria-stabilized zirconia (YSZ) composite and YSZ as the anode and electrolyte materials, respectively. The initial feedrod with a diameter of 22 mm, comprised of three thermoplastic compounds (carbon black (core), NiO–YSZ (intermediate), and YSZ (shell)), was coextruded through various orifices having diameters of 0.5, 1, and 2 mm at 120°C, producing continuous filaments with remarkable size reductions, while preserving the cross section of the initial feedrod. After removing the binder and carbon black used as the core material, the samples were cofired at 1350°C for 3 h in air, producing ceramic tubes with small diameters, ranging from 0.4 to 1.8 mm, where the surfaces of porous NiO–YSZ layers were coated with thin and dense YSZ layers, ranging from 22 to 98 μm.