TOTAL NORMAL AND SPECTRAL EMITTANCE OF REFRACTORY MATERIALS FOR HIGH-TEMPERATURE OVENS

A measurement device based on the radiation comparison technique is de scribed. It enables us to measure the directional total and spectral e mittance between 400-degrees-C and 1200-degrees-C in the wavelength ra nge 0.5 mum to 8 mum and at angles of up to 72-degrees against the nor mal to the surface. Measurements with different types of silica showed that the spectral emittance can be remarkably increased, especially a t wavelengths below 5 mum, by adding small amounts of silicon carbide. This is important for the improvement in the efficiency of the heatin g at different types of furnaces.