The Thermal Emissivity of Some Materials Used in Thermionic Valve Manufacture

C. M. Cade

The laws governing thermal radiation are briefly-reviewed and methods of measuring emissivity are described. The apparatus used by the author is described and an account of possible sources of error is given. Results of other workers are quoted wherever available, and the thermal emissivity over the useful working temperature range is given for the following materials. Metals Alloys Other Surfaces Iron Nichrome BaO-SrO on Nickel Molybdenum Nimonic Carbonized Nickel Nickel Moly-Tungsten Titania on Nickel Tantalum Titania on Iron Tungsten Aluminized Iron Gold Titanium Hydride on Molybdenum Silver Platinum Zirconium Preparations on Ni, Mo and Fe. Alumina Carbon Copyright © 1961—THE INSTITUTE OF RADIO ENGINEERS, INC.

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Materials
Curve 1
Temperature Range, K: 673-1073 Reported Error, %: ±2.5 Composition (weight percent), Specifications and Remarks: TiO₂ (8 mg cm⁻² area density); nickel substrate; 200-300 mesh titanium dioxide; sprayed; sintered at 1273 K in vacuum; measured in vacuum (< 5 x 10⁻⁵ mm Hg); data extracted from smooth curve.
Curve 2
Temperature Range, K: 673-1273 Reported Error, %: ±2.5 Composition (weight percent), Specifications and Remarks: TiO₂ (8 mg cm⁻² area density); soft iron substrate; sprayed; sintered at 1373 K in vacuum; measured in vacuum (< 5 x 10⁻⁵ mm Hg); data extracted from smooth curve.
Curve 1
Temperature Range, K: 773-1473 Reported Error, %: ±2.5 Composition (weight percent), Specifications and Remarks: Titanium hydride in necoloidine (200-300 mesh) binder (6 x 10⁻³ gm cm⁻²) on molybdenum ribbon substrate; sintered at 1573 K in vacuum; measured in vacuum (<5 x 10⁻⁵ mm Hg); data extracted from smooth curve.
Curve 1
Temperature Range, K: 873-1673 Reported Error, %: ±2.5 Composition (weight percent), Specifications and Remarks: 88.5 zirconium metal powder and 11.5 finely powdered graphite suspended in necoloidine binder molybdenum substrate; sprayed to a density of 7.5 mg cm⁻²; sintered at 1773 K; measured in vacuum (<5 x 10⁻⁵ mm Hg); data extracted from smooth curve.
Curve 1
Temperature Range, K: 873-1473 Reported Error, %: ±2.5 Composition (weight percent), Specifications and Remarks: 75 zirconium hydride and 25 zirconia suspended in necoloidine binder on molybdenum substrate; sprayed to a density of 7.5 mg cm⁻²; measured in vacuum (<5 x 10⁻⁵ mm Hg); data extracted from smooth curve.
Curve 2
Temperature Range, K: 873-1273 Reported Error, %: ±2.5 Composition (weight percent), Specifications and Remarks: 85 zirconium hydride and 15 ferric oxide suspended in necoloidine binder on iron substrate; sprayed to a density of 7.5 mg cm⁻²; sintered at 1073 K; measured in vacuum (<5 x 10⁻⁵ mm Hg); data extracted from smooth curve.