Approximate models of radiation scattering in hollow-microsphere ceramics

Theoretical models are suggested, which explain the strong scattering of visible and infrared radiation in hollow-microsphere ceramics and are based on the assumption of predominant scattering of radiation in the contact zones of neighboring microspheres. The approximation of the results of calculations by the Mie theory is used in one of the models to estimate the transport coefficient of attenuation; the other model, which produces approximately the same results, involves the use of solution for radiation scattering by random-oriented plates. The validity of the suggested theoretical description and derived approximate formulas is confirmed by comparing the calculated values of the spectral coefficient of radiation diffusion to the experimental data for two types of heat-insulating ceramics made of hollow spherical particles of alumina.