Near-infrared radiative properties of porous zirconia ceramics

Infrared radiative properties of zirconia ceramics of porosity about 16% are studied by means of the measurements of directional–hemispherical reflectance and transmittance in the wavelength range from 2.5 to 9 μm. The recently suggested modified two-flux approximation is examined as a simplified basis of the identification procedure. A comparison with the exact numerical solution confirms a good accuracy of this approach for identification of the absorption coefficient of ceramics. An analysis of the results for transport scattering coefficient showed that scattering is determined by isotropic pores with characteristic average radius about 1 μm. The corresponding approximate theoretical model of radiative properties of ceramics is suggested. The absorption coefficient of bulk zirconia in the semi-transparency range is obtained from the data for porous zirconia ceramics.