Spectral emissivity, total emissivity, and thermal conductivity of molybdenum, tantalum, and tungsten above 2300°k

Robert D. Allen, Louis F. Glasier Jr., Paul L. Jordan

The emissivities and thermal conductivities of high purity arc melted molybdenum and tantalum and powder metallurgy tantalum and tungsten were measured between 2300°K and their respective melting points. A method is presented for the determination of spectral and total emissivities from the determination of brightness temperature at the center of an electrically heated rod as a function of heat flow rate. The method does not depend on the experimental achievement of blackbody conditions. Spectral emissivities were also determined by measurement of brightness temperatures at the respective melting points. Thermal conductivities of electrically heated rods were determined by the Jain and Krishnan longitudinal heat flow method. The spectral emissivities of tantalum and tungsten decrease linearly with increase in temperature. The spectral emissivity of molybdenum is constant. The total emissivities of molybdenum, tantalum, and tungsten increase with increasing temperature. For any of the metals the spectral and total emissivities are closest to each other at the melting point. The melting point of tantalum is significantly lowered by small increase in impurity content. The thermal conductivities of molybdenum, tantalum, and tungsten decrease linearly with increasing temperature. The ranges of spectral emissivity, total emissivity, and thermal conductivity above 2300°K are as follows: T K cal. cm-1sec.-1K-1 Molybdenum 0.30 0.271-0.285 0.34-0.32 Tantalum 0.361-0.350 0.288-0.324 0.15-0.11 Tungsten 0.37-0.36 0.268-0.352 0.38-0.30 © 1960 The American Institute of Physics.

DOI badge Download BibTeX How to cite Download dataset

Materials
Curve 1
Temperature Range, K: 2300-2900 Composition (weight percent), Specifications and Remarks: 0.18 Fe, 0.073 Si, 0.04 C, 0.036 Mn, 0.005 O2, 0. 01 others, Mo balance; cast under inert gas; hot rolled; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon.
Curve 1
Wavelength μ: 0.65 Temperature Range, K: 2300-3270 Geometry θ': ~0° Composition (weight percent), Specifications and Remarks: 0.0035 Nb, 0.0032 O2, 0.0028 Fe, 0.0016 C, <0.0010 N2, 0.0175 others, Ta balance; cast in vacuum in water-cooled copper mold using consumable electrode, cold rolled, swaged and cold drawn; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tantalum No. 2].
Curve 2
Wavelength μ: 0.65 Temperature Range, K: 2560-2700 Geometry θ': ~0° Composition (weight percent), Specifications and Remarks: <0.02 Si, 0.005 Fe, 0.003 Mo, 0.0008 C, 0.052 others, Ta balance; pressed and sintered metal powder; hot and cold rolled; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tantalum No. 1].
Curve 1
Temperature Range, K: 2300-3100 Composition (weight percent), Specifications and Remarks: <0.02 Si, 0.005 Fe, 0.003 Mo, 0.0008 C, 0.052 others, Ta balance; pressed and sintered metal powder; hot and cold rolled; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tantalum No. 1].
Curve 2
Temperature Range, K: 2300-3200 Composition (weight percent), Specifications and Remarks: 0.0035 Nb, 0.0032 O2, 0.0028 Fe, 0.0016 C, <0.0010 N2, 0.0175 others, Ta balance; cast, in vacuum, in water-cooled copper mold using consumable electrode, cold rolled, swaged, and cold drawn; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tantalum No. 2].
Curve 1
Wavelength μ: 0.65 Temperature Range, K: 2300-3100 Geometry θ': ~0° Composition (weight percent), Specifications and Remarks: 0.04 Mo, 0.006 O2, 0.005 Ni, 0.005 Ti, 0.004 Fe, 0.027 others, W balance; pressed and sintered metal powder; hot worked; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tungsten No. 1].
Curve 2
Wavelength μ: 0.65 Temperature Range, K: 3680 Geometry θ': ~0° Composition (weight percent), Specifications and Remarks: 0.04 Mo, 0.002 Cu, 0.008 others, 99.95 W; pressed and sintered metal powder; hot worked; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tungsten No. 2].
Curve 1
Temperature Range, K: 2300-3400 Composition (weight percent), Specifications and Remarks: 0.04 Mo, 0.002 Cu, 0.008 others, 99.95 W; pressed and sintered metal powder; hot-worked; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tungsten No. 2].
Curve 2
Temperature Range, K: 2300-3400 Composition (weight percent), Specifications and Remarks: 0.04 Mo, 0.006 O2, 0.005 Ni, 0.005 Ti, 0.004 Fe, 0.027 others, W balance; pressed and sintered metal powder; hot-worked; successively polished with No. 1-, 0-, 00-, 000-, and 0000-abrasive papers; measured in argon (>760 mm Hg); [Author's designation: Tungsten No. 1].