98 



TABLES 78-84. 



-EMISSIVITTES OF A NUMBER OF MATERIALS 



TABLE 78.— NORMAL SPECTRAL EMISSIVITIES FOR SOME ELEMENTS 



AND ALLOYS 



The emissivity, spectral or total, of any non-blackbody shows the relation between the 

 intensity of its radiation and that of the blackbody when both are at the same temperature. 

 Spectral emissivities have been measured for a number of materials for different tempera- 

 tures and different wavelength intervals and are shown in Part 1. 



Part 1. — At temperatures generally above 1000 °K at 



Room temperature values are given in a few instances where they, along with values at 

 higher temperatures, form a connected series and where the values given for the higher 

 temperatures depend on those given for low temperatures. 



Emissivity 



s* 



Red Green Blue Remarks 



Temperature , A v , A , , A v 



Material °K X in ft c x X in n e x X in /it f x 



Carbon 1600 .66 .89 



2500 .66 .84 



Copper 1275 .66 .105 Solid 



1350 .66 .120 Solid 



1375 .66 .150 Liquid 



1450 .66 .140 Liquid 



1500 .66 .13 Liquid 



Iron 1000 .66 .27 Solid 



1480-1500 .65 .37 Solid and liquid 



Konal 1200 .665 .43 



Molybdenum .... 300 .665 .420 .467 .425 



1300 .665 .378 .467 .395 



2000 .665 .353 .467 .380 



2750 .665 .332 .467 .365 



Nickel 1200-1650 .665 .375 .535 .425 .460 .450 Solid 



Tantalum 300 .665 .493 .467 .565 



1400 .665 .442 .467 .505 



2100 .665 .415 .467 .460 



2800 .665 .390 .467 



84 Worthing, A. G., Temperature radiation emissivities and emittances, Temperature, Its Measure- 

 ment and Control, p. 1184, Reinhold Publishing Co., 1941. 



Part 2. — Emissivity of a number of metals at their melting point : 



(c\ expressed in percent) 



SMITHSONIAN PHYSICAL TABLES 



