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Emissivity Table for Metals
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These values are approximate and may vary depending on the actual surface of material and conditions.
| Material | Emissivity | | 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 | 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. 4. For semi-transparent materials such as plastic film and glass, assure that the background is uniform and lower in temperature than the object. 5. Hold instrument perpendicular to surface whenever emissivity is less than 0.9. In all cases, do not exceed angles more than 30 degrees from incidence. 6. For 1M and 2M models, avoid measurements in high ambient light conditions. 7. For Raytek MT, ST, or MX, use the 8-14 micron column.
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