Thermal radiation of opaque materials; Rayonnement thermique des materiaux opaques

This article treats only of opaque materials, i.e. materials that are thick enough to avoid the transmission of any part of the incident radiation. This thickness depends on the wavelength considered, on the type of material and on its surface properties: 1 - basic law of thermal radiation: Planck law, blackbody (definition of luminance); 2 - radiative characteristics of opaque materials: relations between radiative characteristics, definition of an opaque body, emissivity of metals and dielectric materials, influence of the surface properties; 3 - radiant heat transfers between opaque materials: notion of form factor, radiative exchanges between black surfaces, radiative exchanges between grey and diffuse surfaces, radiative exchanges between grey and partially specular surfaces, radiative exchanges between non-grey surfaces, surfaces with non-ideal directional properties; 4 - conclusion. (J.S.)