Optical Properties of Domestic Reticulated Vitreous Carbon and Its Base

Abstract

The results of the experimental studies and mathematical modeling of some optical properties of vitreous carbon and reticulated vitreous carbon based materials produced by the technology developed in our country were presented. The study was oriented to the thermal application of materials, so increased attention was focused in this study on the estimation of spectral characteristics influencing the radiation heat transfer in a reticulated structure. Some dense specimens identical to vitreous carbon used as a basis for highly porous cellular carbon materials in their physical properties were preliminarily created. Using the experimentally measured hemispherical reflectance of the surface of specimens under normal illumination, the spectra of the optical constants (refractive and absorption indices) of vitreous carbon and a number of their derivative characteristics were determined by the Kramers–Kronig relations. Some simple approximating relationships convenient for engineering applications were given for them in this paper. The obtained spectral data were incorporated into the earlier developed optical statistical simulation model of ultraporous reticulated materials, which is based on strict electromagnetic theory and provides the possibility to take into account both the specific features of their microstructure and the physical processes occurring in similar systems on different spatial and temporal scales. For reticulated vitreous carbon with wide prospects of application as a constructional and heat-shield material in the aerospace industry, examples of calculating the spectral-kinetic radiation transfer coefficients, the scattering indicatrix variants, and the thermal dependences of the radiation heat conductivity were given. Some additional capabilities of the model were demonstrated.