Emissivity Values for Common Materials & Non-Metals - ircon.com
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Home > IR Education > Emissivity Values - Metals

Emissivity Values for Metals

Emissivity is the measure of an object's ability to emit infrared energy. Emitted energy indicates the temperature of the object. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic, painted, or oxidized surfaces have emissivity values close to 0.95. The majority of Ircon sensors have an adjustable emissivity feature to ensure accuracy when measuring other materials, such as shiny metals.

Please note, these values are to be used as a guide only, as emissivity changes depending on the actual material surface and conditions.

Material Emissivity Values
1.0µm 1.6µm 8-14µm
Aluminum
  Unoxidized 0.1-0.2 0.02-0.2 n.r.
  Oxidized 0.4 0.4 0.2-0.4
Alloy A3003
  Oxidized n.r. 0.4 0.3
  Roughened 0.2-0.8 0.2-0.6 0.1-0.3
  Polished 0.1-0.2 0.02-0.1 n.r.
Brass
  Polished 0.8-0.95 0.01-0.05 n.r.
  Burnished n.r. n.r. 0.3
  Oxidized 0.6 0.6 0.5
Chromium 0.4 0.4 n.r.
Copper
  Polished n.r. 0.03 n.r.
  Roughened n.r. 0.05-0.2 n.r.
  Oxidized 0.2-0.8 0.2-0.9 0.4-0.8
Electrical Terminal Blocks n.r. n.r. 0.6
Gold 0.3 0.01-0.1 n.r.
Haynes
  Alloy 0.5-0.9 0.6-0.9 0.3-0.8
Inconel
  Oxidized 0.4-0.9 0.6-0.9 0.7-.95
  Sandblasted 0.3-0.4 0.3-0.6 0.3-0.6
  Electoropolished 0.2-0.5 0.25 0.15
Iron
  Oxidized 0.4-0.8 0.5-0.9 0.5-0.9
  Unoxidized 0.35 0.1-0.3 n.r.
  Rusted n.r. 0.6-0.9 0.5-0.7
  Molten 0.35 0.4-0.6 n.r.
Iron, Cast
  Oxidized 0.7-0.9 0.7-0.9 0.6-0.95
  Unoxidized 0.35 0.3 0.2
  Molten .035 0.3-0.4 0.2-0.3
Iron, Wrought
  Dull 0.9 0.9 0.9
Lead
  Polished 0.35 0.05-0.2 n.r.
  Rough 0.65 0.6 0.4
  Oxidized n.r. 0.3-0.7 0.2-0.6
Magnesium 0.3-0.8 0.05-0.3 n.r.
Mercury n.r. 0.05-0.15 n.r.
Molybdenum
  Oxidized 0.5-0.9 0.4-0.9 0.2-0.6
  Unoxidized 0.25-0.35 0.1-0.35
Nickel
  Oxidized 0.8-0.9 0.4-0.7 0.2-0.5
  Electrolytic 0.2-0.04 0.1-0.3 n.r.
Platinum
  Black n.r. 0.95 0.9
  Silver n.r. 0.02 .n.r
Steel
  Cold-Rolled 0.8-0.9 0.8-0.9 0.7-0.9
  Ground Sheet n.r. n.r. 0.4-0.6
  Polished Sheet 0.35 0.25 0.1
  Molten 0.35 0.25-0.4 n.r.
  Oxidized 0.8-0.9 0.8-0.9 0.7-0.9
  Stainless 0.35 0.2-0.9 0.1-0.8
Tin (Unoxidized) 0.25 0.1-0.3 n.r.
Titanium
  Polished 0.5-0.75 0.3-0.5 n.r.
  Oxidized n.r. 0.6-0.8 0.5-0.6
Tungsten (Wolfram) n.r. 0.1-0.6 n.r.
  Polished 0.35-0.4 0.1-0.3 n.r.
Zinc
  Oxidized 0.6 0.15 0.1
  Polished 0.5 0.05 n.r.

n.r.=not recommended

To optimize surface temperature measurement accuracy:
1. Determine the object emissivity for the spectral range of the instrument to
be used for the measurement.
2. Avoid reflections by shielding object from surrounding high temperature sources.
3. For higher temperature objects, use shorter wavelength instruments, whenever possible.

 
 
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