- Email: [email protected]
1185. Analysis of gases by the vacuum fusion process
Classified
abstracts
1177-1190
metal. Two axial electron-optical systems comprising focusing, deflecting, and scanning elements with a correction for astigmatism ensure the production of a narrowizone of molten metal in all cases of practical interest. A specially-designed lanthanum hexaboride cathode is the main feature of the electron gun, ensuring long life and reliable operation. V K Popov and B A Popovich, Elektron Obrabot Metal, No 1, 1966, 8X-93 (in Russian). 37
: 33
1177. Electron-beam
apparatus for melting metals. (USSR) A 60 kW electron-beam system for melting titanium, niobium, molybdenum, zirconium, tantalum, and their alloys is described. The melting chamber is 900 mm in diameter and 850 mm long; a set of backing and diffusion pumps reduces the pressure in this chamber to 2 x 10-r’ torr. A nitrogen trap is provided to eliminate contamination from oil vapour. The reliability of the electron-optical system depends on the degree of vacuum in the electron gun, and special provision is made for keeping this constant at 2x 1O-5 torr. The vacuum of the system as a whole is partly governed by the gettering properties of the metals themselves. Lanthanum hexaboride is a suitable cathode material for the electron gun, but the cathode must be protected from drops of molten metals. Whereas oil pumps are suitable for tantalum and niobium, their long-term use is not recommended for molybdenum. V K Popov and E P Demin, Elektron Obrabot Metal, No 2, 1966, 77 (in Russian). 37 :40
in hydrogen. (USSR) A modified version of existing methods of analyzing hydrogen containing traces of other gases is described. Silicagel with a specific surface of 320 m2/g is used as adsorbent for the impurities, and analysis is effected by means of a mass-spectrometer giving the whole spectrum of gaseous impurities simultaneously. The gas samples are selected from the hydrogen stream by means of a special vacuumpump system furnished with liquid-nitrogen traps. The period for which the silicagel has to remain in contact with the hydrogen in order to ensure complete adsorption is determined empirically by reference to the quantity of impurities present, the length of the silicagel column, and the temperature of the hydrogen. Typical pressures in the gas-sampling system range from 10-r to lo-* torr. S V Starodubtsev et al, Fiz Svoist Osobo Chist Metal Poluprovodn, 1966, 18 (in Russian).
material of same composition melted and cast under normal atmospheric pressure. G Blane et al, Fonderie, 1966, 1-I 7. 37 1183. Degassing of Al and light alloys by bubbling through nitrogen
through porous refractory elements. (France) In order to degas a liquid metal using a neutral gas, it is necessary that the latter should have maximum dispersal in the bath, in such a manner that integral sweeping out of the metal is obtained. This condition is best fulfilled by blowing the gas in the form of bubbles as small as possible through the bottom of the liquid metal container. A satisfactory solution to this problem is obtained by blowing nitrogen through porous refractory bottoms. J Galey et al, Fonderie, 1966, 383-395 (in French). 37
1178. Analysis of gaseous micro-impurities
37
1179. Preparation of silicon of high purity. (France) Three methods of obtaining high purity-Si suitable for vacuum fusion purification are described, two of which are the reduction of sodium fluosilicate by either Mg in the presence of Sb, or by Na in the presence of Sb, and the third is the treatment of electrothermic silicon by a metallic solvent (Sb or Sn). E Bonnier et al, Acta Tech Belgique Met, 5, 1966, 299-317 (in French).
: 17
1184. Effective thermal conductivity of packed columns in the low pressure range. (Japan) By means of a modification to the equation of S Yagi and D Kuni, the effective thermal conductivity of packed columns at low pressure in the presence of vapours of various thermal conductivities was calculated. Using glass beads and lead shot (packing diameter 0.19 to 1.95 mm) the effective thermal conductivity of mixtures of He, H,, N1, C,H, and CzHl between 1O-3 and 760 torr were measured. The theoretical equation was found to agree well with experimental results. N Wakao et al, Chem Eng Japan (Kagaku Kogaku), 30 (12), Dee 1966, 1119-I 124 (in Japanese). 37
1185. Analysis of gases by the vacuum fusion process. (Japan) The vacuum fusion process for the extraction of nitrogen in steels gave values which were too low, in the presence of Cr,:Mo, and-V. The values were also too low for carbon monoxide extraction in the presence of W and Mn. T Koizimi et al, Tetsu To Hagane, 50, 1966, 783-793. 37
1186. Vacuum heat treatment of CdS single crystals. (Germany) Changes of the spectral distribution of photoconductive and conductance glow curves, after heat treatment between 370-620°K and immediate quenching of undoped CdS single crystal platelets in ultrahigh vacuum, are described. K W Boer and C A Kennedy, Phys Status Solidi, 19, 1967, 203-210. 37 1187. Degassing kinetics of metal-nitrogen solid solutions. Part I. Theoretical considerations. (Germany) In order to derive the law of degassing kinetics of metal-nitrogen solid solutions, the degassing process has been divided into partial derivatives. An equation system was set up relating the time concentration changes of the reagent with the reaction rates of the partials. G Horg, Z Metalkunde, 57, 1966, 703-708 (in German).
37
37
1180. Purification of antimony by sublimation. (France) The direct distillation under vacuum of commercial purity Sb (99.5 per cent) permits removal of all Ag, Al, Cr, Cu, Fe, Mn, and Ni. It is difficult to remove As, Pb, Sn, and S. Methods of obtaining low residual values in the distillate for these elements are described. E Bonnier and M Charveriat, Acta Tech Belgique Met, 5, 1966,
1188. Vacuum steelmaking. (Rumania) The effect of vacuum on the degassing and refining of steel increases with the intensity of the vacuum, the rise in temperature and the duration of the treatment. However, a vacuum which is too high may lead to unfavourable after-effects such as volatilisation of some alloying elements or reduction of the metal lining. P Dumitracsu and N Murgulet, Metalurgia, 17, 1966, 597-601 (in
3 19-327 (in French). 37
1181. The gases of east iron. Degassing trials. (France) Vacuum melting of cast iron, either by means of an induction furnace or a consumable arc, is too expensive to be industrially important. The degassing of gray and malleable cast irons was effected by casting them under vacuum at 0.5 torr. Simplification of the treatment cycles and improved mechanical properties of these vacuum castings can compensate for the increased installation and process costs for the degassing operation. P Dauxois, Me’tallurgie, 98, 1966, 667-668 (in French). 37 1182. Properties of cast iron remelted and cast under high vacuum.
(France) When cast iron is remelted and cast under high vacuum (1O-3 torr) it has some particular properties; increased tendency to solidify as grey iron, (even if cast in metallic moulds), prevalence of fine interdendritic graphite, higher tensile strength and lower hardness than
Rumanian). 37
1189. Determination of the effect of vacuum degassing on the quantity of inclusions in steel. (Poland) Data are given on laboratory and industrial tests of the effect of vacuum on the content of nonmetallic inclusions in carbon rail steels containing 0.4-0.65 per cent C, 0.61.6 per cent Mn, 0.15-0.35 per cent Si, and 0.09 per cent total of S and P. Fifty ton melts were evacuated by ladling at 2-15 torr pressure. The laboratory investigations were carried out in a vacuum furnace at 0.1-10 torr. T Mazanek et al, Hutnik, 32, 1966, 309-315 (in Polish). 37
1190. Vacuum metallurgy, procedures and equipment. (Australia) A brief review is given of the present status of vacuum metallurgy with emphasis on induction, arc, and electron beam melting. History, construction and operating parameters are given for the vacuum induction furnace, the vacuum arc furnace and the electron beam
abstracts
1177-1190
metal. Two axial electron-optical systems comprising focusing, deflecting, and scanning elements with a correction for astigmatism ensure the production of a narrowizone of molten metal in all cases of practical interest. A specially-designed lanthanum hexaboride cathode is the main feature of the electron gun, ensuring long life and reliable operation. V K Popov and B A Popovich, Elektron Obrabot Metal, No 1, 1966, 8X-93 (in Russian). 37
: 33
1177. Electron-beam
apparatus for melting metals. (USSR) A 60 kW electron-beam system for melting titanium, niobium, molybdenum, zirconium, tantalum, and their alloys is described. The melting chamber is 900 mm in diameter and 850 mm long; a set of backing and diffusion pumps reduces the pressure in this chamber to 2 x 10-r’ torr. A nitrogen trap is provided to eliminate contamination from oil vapour. The reliability of the electron-optical system depends on the degree of vacuum in the electron gun, and special provision is made for keeping this constant at 2x 1O-5 torr. The vacuum of the system as a whole is partly governed by the gettering properties of the metals themselves. Lanthanum hexaboride is a suitable cathode material for the electron gun, but the cathode must be protected from drops of molten metals. Whereas oil pumps are suitable for tantalum and niobium, their long-term use is not recommended for molybdenum. V K Popov and E P Demin, Elektron Obrabot Metal, No 2, 1966, 77 (in Russian). 37 :40
in hydrogen. (USSR) A modified version of existing methods of analyzing hydrogen containing traces of other gases is described. Silicagel with a specific surface of 320 m2/g is used as adsorbent for the impurities, and analysis is effected by means of a mass-spectrometer giving the whole spectrum of gaseous impurities simultaneously. The gas samples are selected from the hydrogen stream by means of a special vacuumpump system furnished with liquid-nitrogen traps. The period for which the silicagel has to remain in contact with the hydrogen in order to ensure complete adsorption is determined empirically by reference to the quantity of impurities present, the length of the silicagel column, and the temperature of the hydrogen. Typical pressures in the gas-sampling system range from 10-r to lo-* torr. S V Starodubtsev et al, Fiz Svoist Osobo Chist Metal Poluprovodn, 1966, 18 (in Russian).
material of same composition melted and cast under normal atmospheric pressure. G Blane et al, Fonderie, 1966, 1-I 7. 37 1183. Degassing of Al and light alloys by bubbling through nitrogen
through porous refractory elements. (France) In order to degas a liquid metal using a neutral gas, it is necessary that the latter should have maximum dispersal in the bath, in such a manner that integral sweeping out of the metal is obtained. This condition is best fulfilled by blowing the gas in the form of bubbles as small as possible through the bottom of the liquid metal container. A satisfactory solution to this problem is obtained by blowing nitrogen through porous refractory bottoms. J Galey et al, Fonderie, 1966, 383-395 (in French). 37
1178. Analysis of gaseous micro-impurities
37
1179. Preparation of silicon of high purity. (France) Three methods of obtaining high purity-Si suitable for vacuum fusion purification are described, two of which are the reduction of sodium fluosilicate by either Mg in the presence of Sb, or by Na in the presence of Sb, and the third is the treatment of electrothermic silicon by a metallic solvent (Sb or Sn). E Bonnier et al, Acta Tech Belgique Met, 5, 1966, 299-317 (in French).
: 17
1184. Effective thermal conductivity of packed columns in the low pressure range. (Japan) By means of a modification to the equation of S Yagi and D Kuni, the effective thermal conductivity of packed columns at low pressure in the presence of vapours of various thermal conductivities was calculated. Using glass beads and lead shot (packing diameter 0.19 to 1.95 mm) the effective thermal conductivity of mixtures of He, H,, N1, C,H, and CzHl between 1O-3 and 760 torr were measured. The theoretical equation was found to agree well with experimental results. N Wakao et al, Chem Eng Japan (Kagaku Kogaku), 30 (12), Dee 1966, 1119-I 124 (in Japanese). 37
1185. Analysis of gases by the vacuum fusion process. (Japan) The vacuum fusion process for the extraction of nitrogen in steels gave values which were too low, in the presence of Cr,:Mo, and-V. The values were also too low for carbon monoxide extraction in the presence of W and Mn. T Koizimi et al, Tetsu To Hagane, 50, 1966, 783-793. 37
1186. Vacuum heat treatment of CdS single crystals. (Germany) Changes of the spectral distribution of photoconductive and conductance glow curves, after heat treatment between 370-620°K and immediate quenching of undoped CdS single crystal platelets in ultrahigh vacuum, are described. K W Boer and C A Kennedy, Phys Status Solidi, 19, 1967, 203-210. 37 1187. Degassing kinetics of metal-nitrogen solid solutions. Part I. Theoretical considerations. (Germany) In order to derive the law of degassing kinetics of metal-nitrogen solid solutions, the degassing process has been divided into partial derivatives. An equation system was set up relating the time concentration changes of the reagent with the reaction rates of the partials. G Horg, Z Metalkunde, 57, 1966, 703-708 (in German).
37
37
1180. Purification of antimony by sublimation. (France) The direct distillation under vacuum of commercial purity Sb (99.5 per cent) permits removal of all Ag, Al, Cr, Cu, Fe, Mn, and Ni. It is difficult to remove As, Pb, Sn, and S. Methods of obtaining low residual values in the distillate for these elements are described. E Bonnier and M Charveriat, Acta Tech Belgique Met, 5, 1966,
1188. Vacuum steelmaking. (Rumania) The effect of vacuum on the degassing and refining of steel increases with the intensity of the vacuum, the rise in temperature and the duration of the treatment. However, a vacuum which is too high may lead to unfavourable after-effects such as volatilisation of some alloying elements or reduction of the metal lining. P Dumitracsu and N Murgulet, Metalurgia, 17, 1966, 597-601 (in
3 19-327 (in French). 37
1181. The gases of east iron. Degassing trials. (France) Vacuum melting of cast iron, either by means of an induction furnace or a consumable arc, is too expensive to be industrially important. The degassing of gray and malleable cast irons was effected by casting them under vacuum at 0.5 torr. Simplification of the treatment cycles and improved mechanical properties of these vacuum castings can compensate for the increased installation and process costs for the degassing operation. P Dauxois, Me’tallurgie, 98, 1966, 667-668 (in French). 37 1182. Properties of cast iron remelted and cast under high vacuum.
(France) When cast iron is remelted and cast under high vacuum (1O-3 torr) it has some particular properties; increased tendency to solidify as grey iron, (even if cast in metallic moulds), prevalence of fine interdendritic graphite, higher tensile strength and lower hardness than
Rumanian). 37
1189. Determination of the effect of vacuum degassing on the quantity of inclusions in steel. (Poland) Data are given on laboratory and industrial tests of the effect of vacuum on the content of nonmetallic inclusions in carbon rail steels containing 0.4-0.65 per cent C, 0.61.6 per cent Mn, 0.15-0.35 per cent Si, and 0.09 per cent total of S and P. Fifty ton melts were evacuated by ladling at 2-15 torr pressure. The laboratory investigations were carried out in a vacuum furnace at 0.1-10 torr. T Mazanek et al, Hutnik, 32, 1966, 309-315 (in Polish). 37
1190. Vacuum metallurgy, procedures and equipment. (Australia) A brief review is given of the present status of vacuum metallurgy with emphasis on induction, arc, and electron beam melting. History, construction and operating parameters are given for the vacuum induction furnace, the vacuum arc furnace and the electron beam