Measurement of infrared absorption of some oxides in connection with the radiative transfer in porous and fibrous materials
It is shown in the case of Al/sub 2/O/sub 3/ and MgO that the analysis of absorption data as a function of temperature gives the possibility of decomposing the lattice absorption coefficient in its different multiphonon contributions. Measurements performed on TiO/sub 2/ and ZrO/sub 2/ also are reported; it is observed that electronic effects considerably enhance the absorption level at high temperatures. From diffuse reflection measurements on a scattering sample, the ratio of absorption and scattering can be obtained. So experimental data can be used to calculate the radiant flux. Several models have been proposed, based on isotropic and anisotropic approximations. They involve the absorption coefficient sigma/sub a/, the scattering coefficient sigma/sub s/, the backscattered fraction factor b, and a phase function parameter a/sub 1/. Due to the approximations on which the models are based, the calculated values of the radiant heat flux show large differences (as large as 30%), whatever the accuracy of the values of optical parameters which are used. It appears worthy to use the experimental data on sigma/sub a/ and sigma/sub s/, which can be obtained from transmission and diffuse reflection measurements.
- Research Organization:
- Universite d'Orleans, France
- OSTI ID:
- 6878028
- Journal Information:
- Int. J. Thermophys.; (United States), Vol. 8:1
- Country of Publication:
- United States
- Language:
- English
Similar Records
Boundary conditions for the diffusion equation in radiative transfer
Novel discrete ordinates radiative modeling in reticulated porous ceramics
Related Subjects
ALUMINIUM OXIDES
ABSORPTIVITY
INFRARED SPECTRA
MAGNESIUM OXIDES
TITANIUM OXIDES
ZIRCONIUM OXIDES
ABSORPTION
DIELECTRIC PROPERTIES
FOURIER TRANSFORM SPECTROMETERS
HEAT FLUX
INFRARED RADIATION
INFRARED SPECTROMETERS
LATTICE VIBRATIONS
PHONONS
RADIANT HEAT TRANSFER
SCATTERING
TEMPERATURE DEPENDENCE
THERMAL INSULATION
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ENERGY TRANSFER
HEAT TRANSFER
MAGNESIUM COMPOUNDS
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
QUASI PARTICLES
RADIATIONS
SPECTRA
SPECTROMETERS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies