Effect of foam properties on radiative properties of open-cell silicon carbide foams

Low density and small-cell size foams can be used in thermal protection and/or thermal insulation systems. At high temperature (>1000K) thermal radiation may be important or dominate heat transfer in the foam; however, studies based on more detailed thermal radiation analysis are limited due to the lack of detailed information on radiative properties of foams. Of particular interest of this study is to understand how the properties of foam material such as its density and mean cell size affect the radiative properties of silicon carbide (SiC) foams. In this paper, the dimensionless strut diameter is considered as an important parameter of foams, and the radiative properties of foams are analyzed using the Mie scattering theory. Also, the spectral extinction coefficients of SiC foams are measured experimentally in the laboratory at room temperature. The mean radiative properties are calculated at 1000 K and compared with theoretical calculations, and the data are found to agree well with the predictions. The attenuation/extinction behavior of SiC foams can be characterized by the approach presented in this study. The results should be useful for applications of foams at high temperature.

► Radiative transfer in low density high PPI (pores per inch) silicon-carbide (SiC) foams has been investigated. ► Mean scattering albedo for low density SiC foams is found to be about 0.6 at 1000 K. ► Mean asymmetry factor for low density SiC foams is found to be about 0.53 at 1000 K. ► Mean extinction coefficient increases with SiC foam density and PPI. ► Experimental data agree well with the model predictions.