Transmittance characteristics of metal foams with single layer cellular structure

Simplified geometric model of open-cell aluminum metal foams is developed in this article. The transmittance of unit cell of metal foams with single layer cellular structure normally illuminated by linear polarized plane wave is obtained using Finite Integral Method. Based on Fresnel-Kirchhoff diffraction theory, influence of porosity, pore size, thickness and ligament structure on radiative properties of metal foams is analyzed. As the wavelength of incident electromagnetic wave approaches the pore size, scattering effect becomes significant and translucency of metal foams tends to emerge. Transmittance of metal foams of different porosity varies along similar trend. As the wavelength decreases further, influence of diffraction effect on transmittance of metal foams becomes dominant, and distribution of diffraction energy flow in pore structure can be approximately described using Fresnel-Kirchhoff diffraction theory. In the case of diffraction effect predominating in the energy transfer, influence of pore size on diffraction behavior is negligible for metal foams with the same porosity, while thickness, porosity and ligament structure place significant influence on transmittance of metal foams.