10
Aluminum oxide at 260
℃
0.6
Aluminum oxide at 800
℃
0.3
Aluminum Alloys various
0.1 to 0.25
Brass
Brass (polished)
0.1*
Brass (roughened surface)
0.2
Brass (oxidized)
0.6
Copper
Copper (polished)
0.05*
Copper plate (oxidized)
0.8
Molten copper
0.15
Lead
Lead (pure)
0.1*
Lead (oxidized at 25
℃
)
0.3
Lead (oxidized , reated to 200
℃
)
0.6
Nickel and its alloys
Nickel (pure)
0.1*
Nickel plate (oxidized)
0.4 to 0.5
Nichrome 0.7
Nichrome (oxidized)
0.95
Emissivity Values; Non-metals
Refractory & Building materials
Red brick (rough)
0.75 to 0.9
Fire clay
0.75
Asbestos 0.95
Concrete 0.7
Marble 0.9
Carborundum 0.85
Plaster 0.9
Alumina (fine grain)
0.25
Alumina (coarse grain)
0.45
Silica (fine grain)
0.4
Silica (coarse grain)
0.55
Zirconium silicate up to 500
℃
0.85