233. Method of observing electron paramagnetic resonance at helium temperatures

Classified abstracts 228-244 37 228. Gas liberation from tungsten at 2,500°C. (USSR) Sintered W specimens and those melted by vacuum arc remelting and electron beam techniques are subjected to vacuum degassing in suspended state at 2,500°C in vacuum. The concentrations of H2, CO, CO~ and N2 and the degassing rates for each type of specimen are determined by mass spectrometry. C V T Burtsev et al, Poroshkovaya Met, 1, 1966, 50-54 (in Russian). 37 229. Isothermal release of ionically pumped inert gases. (USA) The release of He, Ar and Xe, ionically pumped into Pyrex glass surfaces, is studied as a function of time after the cessation of pumping. Both pumping and release are conducted at room temperature. The parameters of pumping pressure and pumping time are varied in a dynamic system so that the pressure during pumping is maintained constant. The results are interpreted in terms of release from capture sites in the glass that possess a spectrum of activation energies for desorption. G P Smeatun and G Carter, J Vae Sci Technol, 3, 1966, 208-213. 37 230. Degassing improves quality, extends fatigue life of steel. (USA) Vacuum degassing of steels produces large ingots and forgings largely free from flaking and internal rupturing for critical applications such as large steam turbine or generator rotors. A A Conrad et al, Soc Automotive Engrs J, 74, 1966, 53-56. 37 231. Heat transfer in vacuum-treated loose fibrous materials. (USSR) The high thermally-insulating properties of loose fibrous material subjected to vacuum treatment are discussed and compared with those of similarly-treated powders. Fibrous thermal insulators may be used over a wide temperature range, from the temperature of liquid helium to 2500°C; typical fibrous insulators are made from graphite or zirconium oxide. Some experimental tests on the thermophysical properties of vacuum-treated fibrous substances are described and the laws governing heat transfer in such media are determined. V M Kostylev, Teplofiz Vysok Temp, 4 (3), 1966, 351 (in Russian). 37 232. Effect of temperature condition on properties and gas-saturation of Cr-Ni alloy in vacuum remelting. (USSR) A Ni alloy containing 20 per cent Cr was remelted in a vacuuminduction furnace, and used to study the effects of the production process on its properties and gas content. S D Gagin, Liteinoe Proizv, 11, 1966, 5-7 (in Russian). 37 233. Method of observing electron paramagnetic resonance at helium temperatures. ( USSR) Simple equipment for measuring EPR spectra at helium temperatures in a standard 3-cm radiospectrometer is described. The cryostat is designed so as to allow a change of specimen during the course of the measurements. Special care is required in assembling the helium Dewar; its main working parts are made of thin-walled glass tubing with a minimum Fe + + + content, and the dimensions must be very precise. The nitrogen Dewar is of foam plastic. Cryostats of this type have been operating successfully for the past year; with helium Dewars of 200 cc they suffice for an hour's work, including change of specimens. Some typical spectra are illustrated. N S Garif'yanov and E G Kharakhash'yan, Pribory i Tekh Eksper,

No 1, 1966, 225 (in Russian). 37 234. Preparation of molybdenum and rhenium foil for nuclear investigations. ( USSR ) A method for the preparation of foil 1 to 7 microns thick by thermal dissociation of ReC15 or MoCI5 under vacuum of the order 104 torr, is described. A P Klyucharev et al, Pribory Tekh Eksper, 11 (4), July-Aug 1966

197-198 (in Russian). 37 235. Rapid determination of nitrogen in steels by vacuum melting.

(Germany) The sample of steel is melted with about 1 per cent cerium in a graphite crucible. The crucible is spun on its vertical axis and the sample is 99.9 per cent degassed at 1600°C in 1.5 to 3.5 minutes. Gerhardt et al, Z Anal Chem, 218, 1966, 192-196 (in German).

37 236. Vacuum two-capillary pycnometer for measuring the density of metallic melts. (USSR) A vacuum silica glass pycnometer is described, which contains a second capillary for feeding the pycnometer. Kh I Ibragimov et al, Zh Fiz Khim, 40, 1966, 957-959 (in Russian). 37 237. Vacuum-thermal dissociation of molybdenum diselenide and diteiluride. ( USSR) The thermal behaviour of MoS2 and MoTe~ in vacuum was studied. A A Opalovsky and V E Fedorov, Neorg Material), 2, 1966, 443--446

(in Russian). 37 238. The use of wire gauze baffles in the vacuum columns for distilling mazuts. ( USSR) M A Mamadov et al, Neftepererabotka i Neftekhim, No 4, 1966,

34-36 (in Russian). 37 239. High vacuum casting with electron bombardment heating. (USA) An apparatus for vacuum casting is described in which a continuously cast void-free ingot is formed. Molten material is continuously supplied into the open top of a liquid-cooled annular mould in a high-vacuum tank from the bottom of which a cast material can be continuously withdrawn as a rod-like ingot. C W Hanks and H R Smith, US Patent 3,247,554 26th April 1966,

Appl 30th Sept 1958 and 6th Aug 1962, 3 pages. 37 : 33 240. Anti-emission alloy. (USSR) A method of reducing the emission of electrons from molybdenum components in electrical vacuum apparatus is described. Small quantities of zirconium (0.1--4 wt per cent) are added to the original molybdenum; this reduces the electron emission by a factor of 100 under otherwise equal conditions, and the alloy may therefore be used as an anti-emission material. The purity of the original molybdenum and zirconium must be at least 99.9 per cent. The alloy may be prepared by arc or electron-beam welding. The emission and absorption properties of the alloy make it especially useful for manufacturing electrodes to be used in apparatus incorporating oxide, barium, thorium, and lanthanum boride cathodes. B Ch Dyubua et al, USSR Patent No 177,991, Appl 2nd Feb 1965,

pubt'd 16th Feb 1966. 38. Distillation, organic chemistry, isotopic gas a n a l y s i s 38 24L Mass-spectrometerstudy of kinetics of polymer destruction by the effect of volatile product release. (USSR) The design of apparatus for studying the mass-spectra of volatile products from mechanically loaded polymers is described. All experiments took place at pressures of 10-6 to 10-7 tort in a radio frequency mass-spectrometer. The results of these experiments are presented. V R Regel and T M Muinov, Fiz Tverd Tela, 8 (8), Aug 1966, 2364-

2369 (in Russian).

IV. Materials and techniques used in vacuum technology 40. Gases and vapours 40 242. Adsorption of carbon-monoxide on a tungsten (110) surface. (USA) J W May and L H Germer, J Chem Phys, 44 (8), 15 April 1966, 2895-2902. 40 243. Absorption, photoionizatiun and fluorescence of C02. (USA) G R Cook et al, J Chem Phys, 44 (8), 15 April 1966, 2935-2942. 41. Metals and alloys 41 244. Chemisorption of electronegative gases on refractory metals.

(USA) Some aspects of the chemisorption of chlorine on tungsten and chlorine and hydrogen chloride on hafnium for temperatures of 1800-2200°K and pressures of 4.0 to 6.0× 10-6 tort are discussed. For tungsten the sticking probability of chlorine was about 4 × 10-~ and tended to decrease with temperature. For hafnium the sticking

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