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374. Thermal conductivity of nitrogen-carbon dioxide mixtures
Abstracts
312
Materials 40.
and Techniques
used in Vacuum
Gases and Vapours 40
373. Separation of Gas Mixtures in a Supersonic Jet. In 1954, E. W. Becker and co-workers in Marburg, Germany, discovered that large composition gradients existed in the supersonic jet generated by expanding a gas mixture through a Lava1 nozzle. Further experimental observations of this effect are presented for the mixtures A-N,, 0,-N,, and N,-C,HI, showing characteristics of the phenomenon not previously reported. A quantitative theory based on free-molecule kinetics is suggested, and gives reasonable agreement with the experimental results in several respects. (Author) P. C. Waterman and S. Alexander Stern, J. Chem. Phys., 31, 405-419, Aug. 1959. 40 374. Thermal Conductivity of Nitrogen-Carbon Dioxide Mixtures. Note by Richard S. Brokaw, J. Chem. Phys., 31, 571-572, Aug. 1959. 40 375. Adsorption of Nitrogen on Tungsten at very low Pressures. Italy. Adsorption measurements of nitrogen on a thin tungsten ribbon in the pressure range of 1O-8-2~ lo-’ Torr, and at temperatures lying between 90 and 481”K, have been performed by using a new technique. The amount of adsorbed nitrogen is practically independent of the pressure in the range investigated. The adsorption rate is proportional to the pressure. At room temperature a fraction of the surface is covered by an irreversible film. At 90 “K, beside the above film, two other types of adsorption were found: the first irreversible at 481”K, and the second reversible below 160 “K. The sticking probability is independent of the pressure and almost constant until a high coverage is reached. Its value at low degrees of coverage (about 0.03) is rather lower than the values found by other authors, which however show quite large differences with each other. Some possible sources of such a scattering of data are analysed and discussed. G. Saini, F. Ricca, and A. Nasini, La ricerca scientifca, Anno 29 “, No. 7, Luglio 1959. 40 : 14 : 16 : 30 The Diffusion of Impurities into Evaporating Silicon. See Abstr. 349. 40 : 27 : 37 : 47 Materials and Processes of Electron Devices. See Abstr. 356.
41.
31-3-317
components : vacuum system, power supply, anode support, and traversing cathode. Included is a brief r&urn& on the theory of refining by this technique. Spectrographic analyses along the length of a purified tungsten rod indicate that molybdenum may not be removed by zone refining, but rather by volatilization. Further, X-ray diffraction studies show that tungsten rods purified in this manner are single crystals and these crystals as grown from the melt do not exhibit preferential growth. It is demonstrated, by bending one of the single crystals, that the purified tungsten rods have relatively high ductility. (Author) R. G. Carlson, J. Electrochem.
42.
Material
VL %A1203
Sapphire (single crystal) Alumina A Alumina Alumina Alumina Alumina
B C D E
100 99 97 96 94 85
Properties
30x 42x 28 x 30x 19x 20 x
104
104 104 104 104 104
6.5 x 3.4 x 2.7 x 2.6 x 1.5 x 1.8 x
104 104 104 104 104 104
I.
TABLE
Glass and Ceramics
Properties
Dielectric loss Resistivity at 500°C Tensile strength Flexural strength Compressive strength
1
and structure properties
.4W3
/ ~ Steatite 1
2 x 10-S
1000x10-5
50x10-5
~
1 x 1011 65,000 115,000
:
50,000
) Alumina ceramic 50x10-5
1x 10’0
1x10-c 5,000 8,000
300,000
on physical measured at
of Ceramic Materials Glass or porcelain
Single crystal
10,000 18,000
I x 10’0 ~ 25,000 50,000
i 65,000 I
200,000
Graphs are,given for the variation of dielectric constant and loss tangent with temperature (25-500 “C) and frequency (1 Kc10 KMc) for low-loss steatite. w. H. K. M. D. Rigterink,
of High
Mechanical (_,L___--, Compressive Tensile strength strength (lblin.2, 25 “C) ~ (lb/in.2, 25 “C)
Jan. 1959.
106,49-53,
demonstrate the effect of composition and mechanical properties (dielectric I MC) :
41 376. Tungsten Zone Melting by Electron Bombardment. United States. An apparatus for refining tungsten in vacuum by the floating zone method is described. It consists of four
Some
Sot.,
42 377. Ceramic Electrical Insulating Materials. United States. A review is presented of the relative merits of various ceramic insulating materials, particularly electrical porcelain, steatite, and alumina, which is illustrated by a series of microphotographs taken both by optical and electron microscopes. These photographs strikingly illustrate the difference in microstructure, the presence or absence of a glassy phase, and of voids. The following tables, taken from the author’s paper,
Metals and Alloys
TABLE II.
Technology
Alumina
Ceramic
J. Amer.
Ceram.
Sot.,
41, 501-506,
Materials
Thermal
Electrical Dielectric constant (1 mc., 25 “C) 10.3 10.0 9.5 9.0 9.2 8.2
Nov.
Dissipation factor (I mc., 25 “C) _ ___ __o.oooo4 0.0001 0.0001 0.0003 0.0004 0.0009
Coefficient of linear expansion (25 ’ to 700 “C) 8.5 8.0 9.0 9.0 7.3 7.9
x x x x x x
104 104 10-6 lo-6 lo” 10-e
Softening temperature (“C) 2040 2 1600 >1600 >1600 >1600 1400
1958.
312
Materials 40.
and Techniques
used in Vacuum
Gases and Vapours 40
373. Separation of Gas Mixtures in a Supersonic Jet. In 1954, E. W. Becker and co-workers in Marburg, Germany, discovered that large composition gradients existed in the supersonic jet generated by expanding a gas mixture through a Lava1 nozzle. Further experimental observations of this effect are presented for the mixtures A-N,, 0,-N,, and N,-C,HI, showing characteristics of the phenomenon not previously reported. A quantitative theory based on free-molecule kinetics is suggested, and gives reasonable agreement with the experimental results in several respects. (Author) P. C. Waterman and S. Alexander Stern, J. Chem. Phys., 31, 405-419, Aug. 1959. 40 374. Thermal Conductivity of Nitrogen-Carbon Dioxide Mixtures. Note by Richard S. Brokaw, J. Chem. Phys., 31, 571-572, Aug. 1959. 40 375. Adsorption of Nitrogen on Tungsten at very low Pressures. Italy. Adsorption measurements of nitrogen on a thin tungsten ribbon in the pressure range of 1O-8-2~ lo-’ Torr, and at temperatures lying between 90 and 481”K, have been performed by using a new technique. The amount of adsorbed nitrogen is practically independent of the pressure in the range investigated. The adsorption rate is proportional to the pressure. At room temperature a fraction of the surface is covered by an irreversible film. At 90 “K, beside the above film, two other types of adsorption were found: the first irreversible at 481”K, and the second reversible below 160 “K. The sticking probability is independent of the pressure and almost constant until a high coverage is reached. Its value at low degrees of coverage (about 0.03) is rather lower than the values found by other authors, which however show quite large differences with each other. Some possible sources of such a scattering of data are analysed and discussed. G. Saini, F. Ricca, and A. Nasini, La ricerca scientifca, Anno 29 “, No. 7, Luglio 1959. 40 : 14 : 16 : 30 The Diffusion of Impurities into Evaporating Silicon. See Abstr. 349. 40 : 27 : 37 : 47 Materials and Processes of Electron Devices. See Abstr. 356.
41.
31-3-317
components : vacuum system, power supply, anode support, and traversing cathode. Included is a brief r&urn& on the theory of refining by this technique. Spectrographic analyses along the length of a purified tungsten rod indicate that molybdenum may not be removed by zone refining, but rather by volatilization. Further, X-ray diffraction studies show that tungsten rods purified in this manner are single crystals and these crystals as grown from the melt do not exhibit preferential growth. It is demonstrated, by bending one of the single crystals, that the purified tungsten rods have relatively high ductility. (Author) R. G. Carlson, J. Electrochem.
42.
Material
VL %A1203
Sapphire (single crystal) Alumina A Alumina Alumina Alumina Alumina
B C D E
100 99 97 96 94 85
Properties
30x 42x 28 x 30x 19x 20 x
104
104 104 104 104 104
6.5 x 3.4 x 2.7 x 2.6 x 1.5 x 1.8 x
104 104 104 104 104 104
I.
TABLE
Glass and Ceramics
Properties
Dielectric loss Resistivity at 500°C Tensile strength Flexural strength Compressive strength
1
and structure properties
.4W3
/ ~ Steatite 1
2 x 10-S
1000x10-5
50x10-5
~
1 x 1011 65,000 115,000
:
50,000
) Alumina ceramic 50x10-5
1x 10’0
1x10-c 5,000 8,000
300,000
on physical measured at
of Ceramic Materials Glass or porcelain
Single crystal
10,000 18,000
I x 10’0 ~ 25,000 50,000
i 65,000 I
200,000
Graphs are,given for the variation of dielectric constant and loss tangent with temperature (25-500 “C) and frequency (1 Kc10 KMc) for low-loss steatite. w. H. K. M. D. Rigterink,
of High
Mechanical (_,L___--, Compressive Tensile strength strength (lblin.2, 25 “C) ~ (lb/in.2, 25 “C)
Jan. 1959.
106,49-53,
demonstrate the effect of composition and mechanical properties (dielectric I MC) :
41 376. Tungsten Zone Melting by Electron Bombardment. United States. An apparatus for refining tungsten in vacuum by the floating zone method is described. It consists of four
Some
Sot.,
42 377. Ceramic Electrical Insulating Materials. United States. A review is presented of the relative merits of various ceramic insulating materials, particularly electrical porcelain, steatite, and alumina, which is illustrated by a series of microphotographs taken both by optical and electron microscopes. These photographs strikingly illustrate the difference in microstructure, the presence or absence of a glassy phase, and of voids. The following tables, taken from the author’s paper,
Metals and Alloys
TABLE II.
Technology
Alumina
Ceramic
J. Amer.
Ceram.
Sot.,
41, 501-506,
Materials
Thermal
Electrical Dielectric constant (1 mc., 25 “C) 10.3 10.0 9.5 9.0 9.2 8.2
Nov.
Dissipation factor (I mc., 25 “C) _ ___ __o.oooo4 0.0001 0.0001 0.0003 0.0004 0.0009
Coefficient of linear expansion (25 ’ to 700 “C) 8.5 8.0 9.0 9.0 7.3 7.9
x x x x x x
104 104 10-6 lo-6 lo” 10-e
Softening temperature (“C) 2040 2 1600 >1600 >1600 >1600 1400
1958.