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1017. Ion-molecule interaction in the cathode region of a glow discharge
Classified
abstracts
1009-1019
37 : 33 : 41 1009. Zone refining tungsten sheet bars in an electron beam furnace. (USA) This paper describes the preparation, treatment, and properties of purified tungsten processed from the cemented alloy W-4 per cent (7Ni : 3Fe). The raw materials were compacted and then sintered in dry hydrogen at 2800°F for 2 hours to form a cemented alloy blank, which was then heated in air to 750°F and rolled to achieve a reduction of 45-60 per cent to produce sheet bar. Zone refining of the alloy sheet bar was performed in a suitably modified electron beam furnace. Prior to initiation of zone sweeping, the furnace chamber was pumped down to lo-’ torr. By raising the sheet bar at a predetermined rate, the hot zone was made to travel along the length of the bar, sweeping out the nickel and iron to leave purified tungsten. After preheating in hydrogen, the zone-refined sheet bar was then rolled. Illustrations are presented showing the microstructures of the products under various conditions of processing. S V Arnold and N M Parikh, Tram Vat Metal1 Conjkrence, 1964,
tection given against harmful reactions during fabrication processes. The work described here was performed under vacuum in a horizontal induction heating furnace with a moveable hearth, with the aid of a 2-high, 4 in. strip mill with oscillating mill entry and exit tables, all the items being enclosed in a 600-litre vacuum chamber. The investigations relating to refractory alloys covered rolling temperatures ranging from 1500°F to 3000”F, reductions of 20 per cent to 80 per cent, heating times of 10 to 60 min, and vacuum chamber pressures of 1O-4 to 10-l torr. At 10-l torr some deterioration of desirable properties occurred, but the samples could be successfully treated in an environment of 1 x lo-* to 5 x 1O-4 torr pressure of air. Further work is described which evaluates the degree of protection afforded by an argon atmosphere. The results indicate that, under conditions of hot working, an argon atmosphere with less than 2 ppm oxygen and less than 10 ppm water content is as protective against contamination of refractory metals as vacua of 5 x 1O-4 torr pressure of air or less. J Bonchak and W J McElhaney, Trans Vat Metall Conference, 1964,
Amer
Amer
Vat Sot, Boston,
Mass,
1010. Some recent improvements
(1965) .pp 159-174. 37 : 33 (USA)
in electron beam systems.
This paper indicates some refinements in electron beam gun systems which have been made for the purpose of increasing the convenience and stability of operation taking into account ease of maintenance. The items described include a bolt-cathode welding gun capable of beam powers of 6 kW, designed for electron beam welding at high current density, which uses an indirectly-heated tungsten rod cathode called the “bolt”, the flat polished end of the bolt forming the source of the electron beam. This design allows better control of dimensional tolerances and has a high emission density compared with wire filaments. An optical viewing system is incorporated. For electron beam melting at beam powers in the range of 20 kW to 200 kW, particulars are given of a gun design that employs a 12 mm diameter tantalum disc cathode heated by electron bombardment on its back face. Explanatory diagrams illustrate the operation of both types of gun and particulars are given of their performance characteristics. 0 Winkler and G F Barber, Tram Vat Metal1 Conference, 1964, Amer
Vat Sot, Boston,
Mass,
(1965) .pp 145-158. 37
1011. Levitation
melting of beryllium and aluminium.
This report describes a method for levitation melting of 70-120 g charges of aluminium in air, and 60-80 g charges of beryllium in an evacuated vessel at a pressure of 5 x 1O-5 torr. Melts were cast into 1 in. and 18 in. diameter rods without contamination. The limitations of the technique are discussed. (Authors) 1964, 37
: 56
(USA) 1012. The electromagnetic levitation of metals. A variety of subjects connected with the electromagnetic levitation of metals is considered. A complete theoretical description of the phenomenon is given, leading to the basic equations for the lifting force and power input for a metal sphere levitated in an inhomogeneous sinusoidally alternating magnetic field. The suspended metal is controlled either by operating at low frequencies and supplying additional heat, or by operating at high frequencies and employing high thermal conductivity gases, such as hydrogen and helium, to cool the metal. Values relating to the levitation of more than 50 different metals at 0 “C and at their respective melting points are given. Refractory, semiconducting, or dielectric materials can be levitated. Although the use of the technique with large commercial quantities of liquid metals appears discouraging, the levitation of long rods or plane sheets appears feasible. Methods of improving the performance of commercial levitation equipment are discussed. Certain metals, because of their high density and electrical resistivity, are very difficult to levitation melt in a vacuum for considerable periods of time. (Author : abridged) P R Rony, Trans Vat Metal1 Conference, Boston, Mass, (1965) .pp 55-135.
1964,
Amer
Vat 37
1013. Vacuum and inert atmosphere
processing of refractory
1014. Vacuum (USA)
Mass,
(1965) ,pp 34-54.
casting operations
using a plasma
resistance
37 : 41 furnace.
The plasma resistance furnace is basically a carbon arc furnace operating in an argon atmosphere. Above 2800°F the argon gas becomes conducting, causing heat to be generated by the electrical resistance of the argon plasma rather than by the conventional electric arc. The furnace is enclosed in a steel case with a door at the top for inserting moulds. Before casting, the door is closed to effect a vacuum-tight seal and the container is then pumped down to a pressure of approximately 0.5 torr by means of a mechanical pump. The moulds are a ceramic composition and are held in place by pneumatic clamps. The molten metal is cast into the mould by rotating the furnace on its support trunnions. Although the plasma resistance furnace was developed and used initially for making precision stainless steel and superalloy castings, a wide variety of alloys including alloy steels, cast irons, nickel base alloys and cobalt base (Author : abridged) alloys have been melted and cast. D P Duff, Trans Vat Metall Conference, Boston, Mass, (1965) ,pp 213-221.
1964,
Amer
Vat
Sot,
: 41
(USA)
R F Bunshah and R S Juntz, Trans Vat Metal1 Conference, Amer Vat Sot, Boston, Mass, (1965) .pp 136-144.
Vat Sot, Boston,
Sot,
: 41
metals.
(USA) While high-vacuum and high-purity atmospheres are frequently employed in melting, welding and the heat treatment of refractory metals to avoid deleterious contamination, there is often little pro-
37 1015. Three-phase vacuum melting turns out huge ingots. Anon, Iron Age, I96 (10). Sept 1965.56-57.
(USA) 37
(USA) 1016. Plasma electron beam unveiled. R RIrving, Iron .4ge, 196 (12)) Sept 1965,98-99.
38. Distillation, analysis
organic chemistry,
isotopic
A technique for determination of thermodynamic metal systems. See abstract number 949.
IV. Materials and techniques technology
gas 38 : 37 : 17
activities
in liquid-
used in vacuum
40. Gases and vapours
40 : 16
An analysis of physical adsorption isotherms in ultra-high range. See abstract number 948.
vacuum
40 1017. Ion-molecule
interaction
in the cathode
region of a glow dis-
charge. (USA) MM Shahin, J Chem Phys, 43 (5)) Sept 1965.1798-1805. 40 1018. Photoionization and absorption cross-sections and Buorescence of CF,. (USA) G R Cook and B K Clung, J Chem Phys, 43 (5), Sept 1965,17941797. 40 1019. Measurements of the molecular absorption cross-sections and the photoionization of sodium vapour between 1600 and 3700 A. (USA) R D Hudson, J Chem Phys, 43 (5), Sept 1965,1790-1793. 615
abstracts
1009-1019
37 : 33 : 41 1009. Zone refining tungsten sheet bars in an electron beam furnace. (USA) This paper describes the preparation, treatment, and properties of purified tungsten processed from the cemented alloy W-4 per cent (7Ni : 3Fe). The raw materials were compacted and then sintered in dry hydrogen at 2800°F for 2 hours to form a cemented alloy blank, which was then heated in air to 750°F and rolled to achieve a reduction of 45-60 per cent to produce sheet bar. Zone refining of the alloy sheet bar was performed in a suitably modified electron beam furnace. Prior to initiation of zone sweeping, the furnace chamber was pumped down to lo-’ torr. By raising the sheet bar at a predetermined rate, the hot zone was made to travel along the length of the bar, sweeping out the nickel and iron to leave purified tungsten. After preheating in hydrogen, the zone-refined sheet bar was then rolled. Illustrations are presented showing the microstructures of the products under various conditions of processing. S V Arnold and N M Parikh, Tram Vat Metal1 Conjkrence, 1964,
tection given against harmful reactions during fabrication processes. The work described here was performed under vacuum in a horizontal induction heating furnace with a moveable hearth, with the aid of a 2-high, 4 in. strip mill with oscillating mill entry and exit tables, all the items being enclosed in a 600-litre vacuum chamber. The investigations relating to refractory alloys covered rolling temperatures ranging from 1500°F to 3000”F, reductions of 20 per cent to 80 per cent, heating times of 10 to 60 min, and vacuum chamber pressures of 1O-4 to 10-l torr. At 10-l torr some deterioration of desirable properties occurred, but the samples could be successfully treated in an environment of 1 x lo-* to 5 x 1O-4 torr pressure of air. Further work is described which evaluates the degree of protection afforded by an argon atmosphere. The results indicate that, under conditions of hot working, an argon atmosphere with less than 2 ppm oxygen and less than 10 ppm water content is as protective against contamination of refractory metals as vacua of 5 x 1O-4 torr pressure of air or less. J Bonchak and W J McElhaney, Trans Vat Metall Conference, 1964,
Amer
Amer
Vat Sot, Boston,
Mass,
1010. Some recent improvements
(1965) .pp 159-174. 37 : 33 (USA)
in electron beam systems.
This paper indicates some refinements in electron beam gun systems which have been made for the purpose of increasing the convenience and stability of operation taking into account ease of maintenance. The items described include a bolt-cathode welding gun capable of beam powers of 6 kW, designed for electron beam welding at high current density, which uses an indirectly-heated tungsten rod cathode called the “bolt”, the flat polished end of the bolt forming the source of the electron beam. This design allows better control of dimensional tolerances and has a high emission density compared with wire filaments. An optical viewing system is incorporated. For electron beam melting at beam powers in the range of 20 kW to 200 kW, particulars are given of a gun design that employs a 12 mm diameter tantalum disc cathode heated by electron bombardment on its back face. Explanatory diagrams illustrate the operation of both types of gun and particulars are given of their performance characteristics. 0 Winkler and G F Barber, Tram Vat Metal1 Conference, 1964, Amer
Vat Sot, Boston,
Mass,
(1965) .pp 145-158. 37
1011. Levitation
melting of beryllium and aluminium.
This report describes a method for levitation melting of 70-120 g charges of aluminium in air, and 60-80 g charges of beryllium in an evacuated vessel at a pressure of 5 x 1O-5 torr. Melts were cast into 1 in. and 18 in. diameter rods without contamination. The limitations of the technique are discussed. (Authors) 1964, 37
: 56
(USA) 1012. The electromagnetic levitation of metals. A variety of subjects connected with the electromagnetic levitation of metals is considered. A complete theoretical description of the phenomenon is given, leading to the basic equations for the lifting force and power input for a metal sphere levitated in an inhomogeneous sinusoidally alternating magnetic field. The suspended metal is controlled either by operating at low frequencies and supplying additional heat, or by operating at high frequencies and employing high thermal conductivity gases, such as hydrogen and helium, to cool the metal. Values relating to the levitation of more than 50 different metals at 0 “C and at their respective melting points are given. Refractory, semiconducting, or dielectric materials can be levitated. Although the use of the technique with large commercial quantities of liquid metals appears discouraging, the levitation of long rods or plane sheets appears feasible. Methods of improving the performance of commercial levitation equipment are discussed. Certain metals, because of their high density and electrical resistivity, are very difficult to levitation melt in a vacuum for considerable periods of time. (Author : abridged) P R Rony, Trans Vat Metal1 Conference, Boston, Mass, (1965) .pp 55-135.
1964,
Amer
Vat 37
1013. Vacuum and inert atmosphere
processing of refractory
1014. Vacuum (USA)
Mass,
(1965) ,pp 34-54.
casting operations
using a plasma
resistance
37 : 41 furnace.
The plasma resistance furnace is basically a carbon arc furnace operating in an argon atmosphere. Above 2800°F the argon gas becomes conducting, causing heat to be generated by the electrical resistance of the argon plasma rather than by the conventional electric arc. The furnace is enclosed in a steel case with a door at the top for inserting moulds. Before casting, the door is closed to effect a vacuum-tight seal and the container is then pumped down to a pressure of approximately 0.5 torr by means of a mechanical pump. The moulds are a ceramic composition and are held in place by pneumatic clamps. The molten metal is cast into the mould by rotating the furnace on its support trunnions. Although the plasma resistance furnace was developed and used initially for making precision stainless steel and superalloy castings, a wide variety of alloys including alloy steels, cast irons, nickel base alloys and cobalt base (Author : abridged) alloys have been melted and cast. D P Duff, Trans Vat Metall Conference, Boston, Mass, (1965) ,pp 213-221.
1964,
Amer
Vat
Sot,
: 41
(USA)
R F Bunshah and R S Juntz, Trans Vat Metal1 Conference, Amer Vat Sot, Boston, Mass, (1965) .pp 136-144.
Vat Sot, Boston,
Sot,
: 41
metals.
(USA) While high-vacuum and high-purity atmospheres are frequently employed in melting, welding and the heat treatment of refractory metals to avoid deleterious contamination, there is often little pro-
37 1015. Three-phase vacuum melting turns out huge ingots. Anon, Iron Age, I96 (10). Sept 1965.56-57.
(USA) 37
(USA) 1016. Plasma electron beam unveiled. R RIrving, Iron .4ge, 196 (12)) Sept 1965,98-99.
38. Distillation, analysis
organic chemistry,
isotopic
A technique for determination of thermodynamic metal systems. See abstract number 949.
IV. Materials and techniques technology
gas 38 : 37 : 17
activities
in liquid-
used in vacuum
40. Gases and vapours
40 : 16
An analysis of physical adsorption isotherms in ultra-high range. See abstract number 948.
vacuum
40 1017. Ion-molecule
interaction
in the cathode
region of a glow dis-
charge. (USA) MM Shahin, J Chem Phys, 43 (5)) Sept 1965.1798-1805. 40 1018. Photoionization and absorption cross-sections and Buorescence of CF,. (USA) G R Cook and B K Clung, J Chem Phys, 43 (5), Sept 1965,17941797. 40 1019. Measurements of the molecular absorption cross-sections and the photoionization of sodium vapour between 1600 and 3700 A. (USA) R D Hudson, J Chem Phys, 43 (5), Sept 1965,1790-1793. 615