Infrared emission spectrum of silicon carbide heating elements

A method for determining the spectral emittance of a silicon carbide heating element (Globar) was devised and d ata were obtained over the wavelength range 1.25 to 15.25 J.I. for four different temperatures. The spectral emittance at a ll four temperat ures, 482, 649, 816, and 982 C (900, 1,200, 1,500, and 1,800 F ), was found to be approximately constant except for a gradual rise in emittan ce from 1.25 to about 4 J.I. and two minimums in the curves at longer wavelengths. The fi rst of these minimums, wh ich occurred at about 9 J.I., was ascribed to minor a mounts of Si02 present on t he surface of the silicon carbide heating element, whereas the second at about 12.5 J.I. corresponds to one of the strong Raman lines for SiC.