Properties of nanostructured oxide formed during oxidation of a zirconium wire by supercritical water

Synthesis of ZrO₂ during oxidation of a zirconium wire by supercritical water at P = 25 MPa and T = 500 or 525°C has been investigated. It is established that an inhomogeneous nanostructured ZrO₂ layer is formed as a result of oxidation. Rate of 〈Zr〉 oxidation, oxide porosity and morphology, and average size and structure of crystallites are determined. The thermal conductivity of the synthesized ZrO₂ layer in supercritical water and in nitrogen is determined by pulsed electric heating of a partially oxidized wire. The low values of thermal conductivity (about 0.2 W/(m K)) correspond to a layered structure of porous material, with layers orientated parallel to the oxidized-metal surface.