MEASUREMENTS OF THERMAL CONDUCTIVITY AND OPTICAL PROPERTIES OF POROUS PARTIALLY STABILIZED ZIRCONIA

Abstract

Experimental measurements of the high-temperature (300 < T < 800 K) thermal conductivity of highly porous (porosity greater than 80%), partially stabilized zirconia (PSZ) were performed. A method of simultaneously inverting conductivity and extinction coefficient from the experimental data is presented. The effect of natural convection within the porous plates with heating from below was found to be negligible. The thermal conductivity integral (TCI) method was incorporated into the inversion of conductivity and radiative properties from the diffusion approximation of the combined radiation and conduction heat flux measurement. The measured conductivity decreased slightly as the pore size of the PSZ increased. The extinction coefficient decreased with increased pore size, and for pore size greater than 0.6 mm the trend had good agreement with the geometric optics limit prediction.