1024. Degassing chamber

Classified a b s t r a c t s 1017-1031 37 : 31 1017. Melting of nickel at reduced pressure to produce cathodes for electron tubes. (Poland). In an induction vacuum electric furnace three types of electrolytic Ni were melted, one of which was precalcined in an hydrogen atmosphere. The melts were obtained under a pressure of 160 tort He, 220 torr He with subsequent degassing at pressures of 0.I torr, 220-260 torr, and 10-3 torr. J Golonka, Prace Inst Hutn, 17, 1966, 263-270 (in Polish). 37 1018. The effect of alloying elements on oxygen and nitrogen contents of steel after vacuum-arc furnace remelting. (Poland) The Oe and Nz contents of various iron alloys, containing C, Si, Cr, Mn, AI and/or Ti were determined as a function of composition after vacuum-arc-remelting with either consumable or permanent W or graphite electrodes. H Zak, Prace lust Hutn, 18, 1966, 55-61 (in Polish). 37 1019. DH unit operation in a basic openhcarth shop. (Great Britain) A vacuum unit of the Dortmund-H6rder or vacuum lifter type installed in an openhearth shop is designed to treat a 400-ton heat of steel in 25 min. Because of its size the treatment chamber oscillates rather than the ladle. The vessel is supported in a moving gantry which positions the vacuum chamber either over the gas fired heater or over the ladle. The theory of vacuum treatment including carbon deoxidation, nucleation and removal of CO, and inclusion removal is reviewed. A J Parke ct al, J Metals, 17, 1966, 897-901. 37 1020. Induction melting for precision-investment casting. (Great Britain) The advantages of vacuum or air induction melting, for the production of investment castings, are extreme cleanliness and simple and precise control of the melt. The electromagnetic turbulence in a coreless furnace is discussed, and is shown to ensure dispersion of any added ingredient throughout the charge. Pouring methods are discussed and illustrated. E B Gosling, Foundry Trade J, 121, 1966, 453-457. 37 1021. Carbon/oxygen reaction in molten nickel and Ni-10 per cent chromium in a vacuum induction furnace. (China) The reaction was investigated at 1500-1540°C and 10-* torr pressure. Both the C and O2 contents were reduced to very low levels, either by deoxidation with carbon or decarburization with oxygen. T Chung-Ho et al, Acta Met Sinica, 9, 1966, 117-126. 37 1022. Steel degassing equipment. (Great Britain) For the degasification and casting under vacuum of molten steel by means of a vacuum siphon, having an inlet tube into which a carrier gas is introduced, and in which an outlet tube of the vacuum siphon opens into a vacuum chamber, the length of the inlet tube being not less than the head of molten metal. Advantageously, the carrier gas is introduced at two places into the inlet tube at different levels, and several ingot moulds or a continuous casting mould may be provided in the vacuum chamber. (Author) Heraeus GmbH, Brit Patent 1,053,345, Patent Abstr, 7 (4) part 7, 24th Jan 1967, 5. 37 1023. Metal degassing vacuum tank. (Great Britain) The tank is provided with a refractory lining surrounded by a gastight steel jacket. A layer of insulation and a system of conduits are disposed in the space between the jacket and the outer surface of the lining. The conduits are perforated tubes which extend between an upper ring conduit, provided with a connection for a vacuum pump, at the top of the tank, and a lower ring conduit surrounding a metal inlet and outlet aperture in the base of the tank, a closable drain being provided in the latter conduit for discharging condensed water. (Author) Dorthnnd-Horder Huttenunion A G, Brit Patent 1,053,571, Patent Abstr, 7 (5) part 7, 26th Jan 1967, 1. 37 1024. Degassing chamber. (Germany) The chamber for molten iron and steel has a pipe extending from the base to the metal in a ladle below. The melt is degassed in portions which are drawn by vacuum into the chamber and which return through the same pipe into the ladle. The portion of the melt to be

degassed is conveyed, together with a gas which flows into a column of metal in the pipe through a conduit with its outlet in this pipe, into the vacuum chamber where it is degassed. After degassing, the supply of gas to the pipe is cut off. (Author) Dortmund-Horder Huttenunion AG, German Patent 1,230,819, Patent Abstr, 7 (4) part 7, 26th Jan 1967. 1. 38. DISTILLATION, ORGANIC CHEMISTRY, ISOTOPIC GAS ANALYSIS 38 1025. Vacuum distillation and crystal growth of alkali balides. (USA) The basic parameters for obtaining good crystal quality by the Kyropoulous technique are summarized. An apparatus is described which allows vacuum distillation of the starting material followed by crystal growth without air admittance. F Rosenberger, Mat Res Bull, 1, 1966 55-73. 38 1026. Entrainment in the flash zone of a vacuum distillation column. (Yugoslavia) In a refining vacuum column, the lowest side fraction, known as the "6th oil" was dark. Entrainment was checked in the vacuum column using cobalt-60 oleate and was shown to contain asphalt ingredients. After the vacuum column was redesigned, no asphalt ingredients were found in the oil. J Silipetar, Nafta, 17, 1966, 157 (in Croat). 38 1027. Capacity of packed columns in vacuum distillation. (Great Britain) Factors which should be considered in determining the capacity of a packed distillation tower include the arrangements of different size packing material s cold reflux, column heat loss and pressure drop. F G Eichel, Chem Eng, 73, 1966, 197-204. 38 1028. Advances in the technology of molecular distillation. (Great Britain) The development of molecular distillation as a purification technique for high molecular weight organic mixtures is described. Results obtained with several materials are reviewed and it is concluded that the application of high vacuum to chemical processes has reached a halfway stage. The general development of the method from the present laboratory and pilot plant stage to the industrial scale awaits the availability of detailed information on the relevant flow criteria and vapour pressure data. R K Lohwater, Vacuum, 17 (1), January 1967, 1-4.

IV. Materials and techniques used in vacuum technology 40. GASES AND VAPOURS 4O 1029. Theory of the dissociative recombination and associative ionization of hydrogen. (USA) A brief survey is given of experimental information available on dissociative recombination and the inverse process of associative ionization. The mechanisms of the reactions are described in terms of adiabatic potential-energy curves of the ion and of the quasi-molecule formed from the union of ion and electron. Because of the paucity of experimental information, emphasis is placed on hydrogen. A mathematical theory is constructed, based on a Coulomb-Born description of the scattering of ion and electron and on adiabatic treatment of atom-atom collisions. S E Nielsen and J S Dahler, J Chem Phys, 45 (ll), 1st Dec 1966, 4051-4076. 40 1030. Chemionization in N and O mixtures. (USA) The rate of chemionization in mixtures of atomic oxygen and nitrogen was measured. Chemical processes leading to ionization are discussed. R A Young and G St John, J Chem Phys, 45 (11), 1st Dec 1966, 4156-4157. 40 1031. Isotope effects on metastable transitions: C3 Hs D8 and C3. (USA) The mass spectra of propane and perdeuterated propane were studied in a sector mass spectrometer: The relative abundances of

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