Thermal physical (thermal diffusivity and conductivity) and optical (attenuation, absorption and scattering) properties of alumina fiber insulation materials were measured. The measurements of apparent thermophysical properties are based on the method of heating of plate specimens at a constant rate. The determination of the conductive and the radiative components of apparent properties is based on the combined radiative-conductive heat transfer theory (RCHT) and the measurement of optical properties.
The significant influence of the heat radiation component on the apparent thermal physical properties is demonstrated. Other heat transfer mechanisms that affect the apparent thermal conductivity are also analyzed. Limitations of standard methods for measurement of apparent thermal physical properties of semitransparent fiber materials, including anisotropic materials, are discussed.