Ni–YSZ cermet micro-tubes with textured surface

Tubular Ni–YSZ porous cermets, with the external surface textured in the form of submicron size alternating YSZ and porous Ni lamellae aligned perpendicular to the tube surface have been fabricated. The surface of the ceramic tubes of eutectic composition was directionally solidified in the radial direction using the laser zone melting procedure where the power of the laser was adjusted to melt a thin surface layer. The melt solidified in the very high thermal growth radial gradient produced by radiation losses and convention cooling. A crack free layer with typical eutectic lamellar microstructure, with domains aligned perpendicular to the tube surface, was produced along the external surface of the tubes. The porous cermet tubes were prepared by thermo-chemical reduction of the NiO phase in the previously textured binary NiO–YSZ eutectic precursors. After reduction, porous Ni leaves of about 100 nm lateral dimension were confined between the YSZ lamellae in the textured layer. The influence of growth parameters over microstructure size and morphology is discussed.