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754. Notes on the technology of steel degassing
292
Classified Abstracts 752--761
37 : 39 752. Single crystal of molybdenum prepared from polycrystalline
tetrafluoroethylene up to 68 mole per cent were obtained.
rod. U.S.S.R.
Anon., Chem. Energy News, 41 (19), 13 May 1963, 40--43.
A thin polycrystalline rod of molybdenum is supported on flexible contacts and heated electrically in a vacuum of 5 × 10 -~ torr. Current input is regulated to produce a regular increase of temperature ranging from 90°C per hour to as much as 2000°C. It is claimed that single crystals are obtained in this manner which are fully equivalent to those obtained from melts in the usual manner. The new process has the additional advantage of realizing faster rates of growth and is being developed by the Baykova Institute of Metallurgy for commercial exploitation of molybdenum as a heat resisting metal, w.J.s. Anon., New Scientist, 18 (333), 4 April 1963, 30.
W . J. S.
37 : 53 756. Conversion of tetrafluoromethane into tetrafluoroethylene in a low pressure electric arc. U.S.A. Workers at the Massachusetts Institute of Technology have obtained a 64 per cent yield using a 25 kW arc and carbon electrodes. Reactant flow is 25 cc of tetrafluoromethane/sec and pressure is ~ 3 5 0 torr. w.J.s. Anon., Chem. & Engng News, 41 (16), 22 April 1963, 35. 37 757. Vacuum sintering of metal powder parts. (U.S.A.) A. J. Zino, et al., MetalProg., 33 (4), April 1963, 88-92.
37 : 28
753. Present and future possibilities of electronic bombardment. France. The author compares the relative advantages of electronic bombardment with those of other methods of concentrated heating, e.g. the electric arc. Cleanliness, accuracy and large power concentration are the chief qualities which render heating by means of an electron gun attractive. Special requirements for the beam when used for melting, welding or evaporation are discussed. A 40 kW melting furnace is described in detail, including control by servo-mechanisms. In view of the rapid developments in the field of electronics, further progress in electron beam furnaces is anticipated, w.J.s. J. Sommeria, Le Vide, 17 (I00), July/Aug. 1962, 307-311. 37 : 36 754. Notes on the technology of steel degassing. Germany. Two methods of steel degassing are in u s e - t h e one proposed first depends on passing a jet of molten steel into a vacuum chamber, the degassing taking place from the surface of the jet. In the second method, a charge of molten steel in a ladle is kept under vacuum condition for a period during which the " b o i l i n g " of the material ensures degassing. The second method is only feasible if vacuum pumps are available capable of handling efficiently 1 to 1.5 million m3/h at a suction pressure of 1 to 0.5 tort. The problem can be solved by the use of steam ejector pumps, the theory of which is described by the author. Some examples of practical installations are also given. It is stated that the cost of degassing by this method will be of the order of about 12 D M (£1) per ton of steel which is easily recuperated by higher quality and consistency of the final material. W. J, S.
W. Teuher, Le Vide, 11 (100), July/Aug. 1962, 360-368. 37 : 18 755, High intensity electric arc as a chemical reactor for CzF~
synthesis. U.S.A. The reactor, developed by members of the M.t.T., consists of four electrically insulated sections. The central cross-section is 3 in. diameter and serves as the reaction chamber which is electrically floating. The graphite anode has a motordriven feed and is centre-bored to allow the reactant gas (CF4) to flow directly into the centre of the plasma. A power input of 25 kW vaporises the anode at the rate of 10 gm/min, this forming the second reactant. To promote mixing, a magnetic field of 200 G is applied along the electrodes to produce rapid rotation of the arc. At a reactor pressure of 150 tort, yields of
37 : 18 : 40 758. Mass spectroscopy of ions in glow discharges.
vapor.
IV. Water
(U.S.A.)
P. F. Knewstuff and A. W. Tickner, J. Chem. Phys., 38 (2), 15 Jan. 1963, 464-469. 759. Mass spectrometry of ions in glow discharges.
37:40 V. Oxygen.
(U.S.A.) P. F. Knewstubb, P. H. Dawson and A. W. Tickner, J. Chem. Phys., 38 (4), 15 Feb. 1963, 1031-1032. 37 : 16
Ionization by charge transfer of adsorbed gases in mass spectrometers. See Abstr. No. 690.
38.
Distillation, Organic Chemistry, Isotopic Gas Analysis 38
760. Flash evaporator plants for sea-water conversion. Britain) Anon., Engineer, 213, 29 June 1962, 1151-1154. 39.
(Great
Miscellaneous Applications
39:16 761. Use of xenon adsorption for measurement of surface area. Great Britain. Measurements of surface area with xenon adsorption have the advantage that very low dead space corrections are obtained at liquid nitrogen temperature. Now that xenon of sufficient purity can be obtained commercially, the gas should find more extensive application. The author has carried out extensive adsorption measurements on various Ni powders using both krypton and xenon, the results being given in the usual B.E.T. plots. It appears from his results that the effective cross sectional area of the xenon molecule is of the order of 25-27A ~ and the area ratios X e / K r average 1.3. This indicates that the hitherto accepted value for the cross sectional area of the K r molecule (19.5 A s) may be slightly too low. w.J.s. W. A. Cannon, Nature, 197 (4871), 9 March 1963, 1000-I001. 39 : 37
Single crystal of molybdenum prepared from polyerystalline rod. See Abstr. No. 752.
Classified Abstracts 752--761
37 : 39 752. Single crystal of molybdenum prepared from polycrystalline
tetrafluoroethylene up to 68 mole per cent were obtained.
rod. U.S.S.R.
Anon., Chem. Energy News, 41 (19), 13 May 1963, 40--43.
A thin polycrystalline rod of molybdenum is supported on flexible contacts and heated electrically in a vacuum of 5 × 10 -~ torr. Current input is regulated to produce a regular increase of temperature ranging from 90°C per hour to as much as 2000°C. It is claimed that single crystals are obtained in this manner which are fully equivalent to those obtained from melts in the usual manner. The new process has the additional advantage of realizing faster rates of growth and is being developed by the Baykova Institute of Metallurgy for commercial exploitation of molybdenum as a heat resisting metal, w.J.s. Anon., New Scientist, 18 (333), 4 April 1963, 30.
W . J. S.
37 : 53 756. Conversion of tetrafluoromethane into tetrafluoroethylene in a low pressure electric arc. U.S.A. Workers at the Massachusetts Institute of Technology have obtained a 64 per cent yield using a 25 kW arc and carbon electrodes. Reactant flow is 25 cc of tetrafluoromethane/sec and pressure is ~ 3 5 0 torr. w.J.s. Anon., Chem. & Engng News, 41 (16), 22 April 1963, 35. 37 757. Vacuum sintering of metal powder parts. (U.S.A.) A. J. Zino, et al., MetalProg., 33 (4), April 1963, 88-92.
37 : 28
753. Present and future possibilities of electronic bombardment. France. The author compares the relative advantages of electronic bombardment with those of other methods of concentrated heating, e.g. the electric arc. Cleanliness, accuracy and large power concentration are the chief qualities which render heating by means of an electron gun attractive. Special requirements for the beam when used for melting, welding or evaporation are discussed. A 40 kW melting furnace is described in detail, including control by servo-mechanisms. In view of the rapid developments in the field of electronics, further progress in electron beam furnaces is anticipated, w.J.s. J. Sommeria, Le Vide, 17 (I00), July/Aug. 1962, 307-311. 37 : 36 754. Notes on the technology of steel degassing. Germany. Two methods of steel degassing are in u s e - t h e one proposed first depends on passing a jet of molten steel into a vacuum chamber, the degassing taking place from the surface of the jet. In the second method, a charge of molten steel in a ladle is kept under vacuum condition for a period during which the " b o i l i n g " of the material ensures degassing. The second method is only feasible if vacuum pumps are available capable of handling efficiently 1 to 1.5 million m3/h at a suction pressure of 1 to 0.5 tort. The problem can be solved by the use of steam ejector pumps, the theory of which is described by the author. Some examples of practical installations are also given. It is stated that the cost of degassing by this method will be of the order of about 12 D M (£1) per ton of steel which is easily recuperated by higher quality and consistency of the final material. W. J, S.
W. Teuher, Le Vide, 11 (100), July/Aug. 1962, 360-368. 37 : 18 755, High intensity electric arc as a chemical reactor for CzF~
synthesis. U.S.A. The reactor, developed by members of the M.t.T., consists of four electrically insulated sections. The central cross-section is 3 in. diameter and serves as the reaction chamber which is electrically floating. The graphite anode has a motordriven feed and is centre-bored to allow the reactant gas (CF4) to flow directly into the centre of the plasma. A power input of 25 kW vaporises the anode at the rate of 10 gm/min, this forming the second reactant. To promote mixing, a magnetic field of 200 G is applied along the electrodes to produce rapid rotation of the arc. At a reactor pressure of 150 tort, yields of
37 : 18 : 40 758. Mass spectroscopy of ions in glow discharges.
vapor.
IV. Water
(U.S.A.)
P. F. Knewstuff and A. W. Tickner, J. Chem. Phys., 38 (2), 15 Jan. 1963, 464-469. 759. Mass spectrometry of ions in glow discharges.
37:40 V. Oxygen.
(U.S.A.) P. F. Knewstubb, P. H. Dawson and A. W. Tickner, J. Chem. Phys., 38 (4), 15 Feb. 1963, 1031-1032. 37 : 16
Ionization by charge transfer of adsorbed gases in mass spectrometers. See Abstr. No. 690.
38.
Distillation, Organic Chemistry, Isotopic Gas Analysis 38
760. Flash evaporator plants for sea-water conversion. Britain) Anon., Engineer, 213, 29 June 1962, 1151-1154. 39.
(Great
Miscellaneous Applications
39:16 761. Use of xenon adsorption for measurement of surface area. Great Britain. Measurements of surface area with xenon adsorption have the advantage that very low dead space corrections are obtained at liquid nitrogen temperature. Now that xenon of sufficient purity can be obtained commercially, the gas should find more extensive application. The author has carried out extensive adsorption measurements on various Ni powders using both krypton and xenon, the results being given in the usual B.E.T. plots. It appears from his results that the effective cross sectional area of the xenon molecule is of the order of 25-27A ~ and the area ratios X e / K r average 1.3. This indicates that the hitherto accepted value for the cross sectional area of the K r molecule (19.5 A s) may be slightly too low. w.J.s. W. A. Cannon, Nature, 197 (4871), 9 March 1963, 1000-I001. 39 : 37
Single crystal of molybdenum prepared from polyerystalline rod. See Abstr. No. 752.