Abstract
In this paper, an experimental measurement technique of the effective emissivity of powders is presented for a given spectral field, using the reflectance hemisphere method. This technique consists of heating a powder filled into a Teflon (r) cell, through a thin copper layer. The apparent temperature of the powder surface is then measured by an infrared camera, either directly or through an orifice arranged into the hemisphere. The effective emissivity is identified by comparing the flux emitted by the powder surface and that emitted by a specular hemisphere taken as a reference blackbody, for the same temperature and the same spectral wavelength field. The results are presented for a metallic and an insulating powder, and validated with literature values. The effective emissivities of powder mixtures are also presented in this paper.