10. The behaviour of iodine in graphite

10. The behaviour of iodine in graphite

Classified abstracts 1-101 Classified a b s t r a c t s 1-13 on t h i s page Abstracting editor's note The label immediatelyfollowing the title of ea...

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Classified abstracts 1-101 Classified a b s t r a c t s 1-13 on t h i s page

Abstracting editor's note The label immediatelyfollowing the title of each item denotes country or origin of publication, and that at the end of each abstract indicates country of origin of work (where known).

14 : 52

I. General v a c u u m science and engineering

5. Adaptation of lattice liquid model to gas absorption phenomena. (Netherlands) J M Honig and W H Kleiner, Surface Sci, 1 (1), 1964, 71-87.

10. V a c u u m science and technology

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10 : 37

1. The importance of vacuum technique for the production and processing of metals with high melting points. (Germany) Researches carried out during the last few years in the field of metals with high melting points, have shown that the admixture of relatively small amounts of impurities has a deleterious effect on their mechanical properties. This is especially the case when the additions consist of elements with a relatively small atomic radius, such as 02, N2 or C. These elements become embedded in the cubic centred structure of the parent metal, forming a mixed crystal and causing a marked reduction in ductility, especially at moderate temperatures. It appears that commercial molybdenum and tungsten are generally oversaturated with 02, N~ and C, whilst niobium and tantalum are not. Since however the solubilities of these substances differ widely in the two cases, the actual impurities in ppm do not differ widely. The author describes how by a combination of thermal and vacuum treatment the impurities in both classes of high temperature metals can be reduced, special reference being made to vacuum zone melting. (Germany) W JS Bibliography 16 items. R Palme, Vak Technik, 13 (8), Dec 1964, 229-232.

6. Free-molecule drag on evaporating or condensing spheres. (USA) The free-molecule drag on evaporating or condensing spheres is discussed. A gas-surface interaction parameter specifying the fraction of impinging molecules adsorbing on a surface but not undergoing condensation is introduced. The evaluation of this parameter from experimental free-molecule drag measurements is proposed. (Author) J R Brock, JPhys Chem, 68, Oct. 1964, 2862-2864. 14 7. Low pressure flow of gases. (USA) H J M Hanley and W A Steele, JPhys Chem, 68, Oct 1964, 3087-

3088.

16. Gases and solids 16

Method of testing the barium content of tubular gas absorbers. See Abstr. No. 47. 16:49

8. Adsorption of gases activated by electron impact. (USA) H F Winters, J Chem Phys, 41 (9), 1 Nov 1964, 2766-2772.

11. P r o d u c t i o n o f l o w p r e s s u r e s 11:21

2. Some experiments on the effects of back-streaming and of back diffusion on the production of ultra-high vacuum. (Japan) The vacuum system consisted of two oil diffusion pumps working in series. Back streaming was investigated with the help of an omegatron mass spectrometer. Several kinds of gases, such as hydrogen, helium, neon etc., were introduced into the fore vacuum line. The compression ratio of the main pump was of the order of 103 for H~ and He and 105 for Ne. For nitrogen, the compression ratio exceeded 107 and no back diffusion could be observed.

(Japan) A Fujinaga et al, Mits Denki Japan, Lab report, 4, (2), 225-236. 11 3. Vacuum pumping-out unit. (USSR) A circuit embodying an ejector water vapour pump and zeolite trap is described, which allows either continuous or periodic pumping out of low sorbing inert gases. (USSR) E N Martiuson and B I Plechev, Patent No. 159598, 28 Dec 1963,

Bulletin No. 1.

14. Kinetic theory of gases 14

Thermal molecular manometer according to H Klumb fitted with magnetic suspension. See Abstr. No. 55. 14 : 22

16 : 40 9. Theory of adsorption of the isotopic hydrogen molecules at low

temperatures. (USA) A Katorski and David White, J Chem Phys, 40 (11), 1 June 1964, 3183-3194. 16 : 41 10. The behaviour of iodine in graphite. (Great Britain) With the help of tracer technique, the adsorption of iodine on type TSX graphite was examined at temperatures ranging from 100 ° to 800°C and pressures between 10 -3 and 15 torr. At the lower temperatures, the iodine was adsorbed both chemically and physically, at higher temperatures chemisorption predominated. Adsorption was increased considerably by previous degassing at 2000°C. Heating in vacuo at 950°C, even over long periods, did not remove all trace of iodine. W J S F J Salzano, Carbon, 2 (1), Aug 1964, 73-81. 16 : 52 11. Chemisorption and ordered surface structures. (Netherlands) Surface structures formed by chemisorption have been examined by means of low energy electron diffraction. Complex interactions leading to first order transitions and reconstruction of substrate atoms were observed. Factors determining surface structure are enumerated and their effect on order-disorder phenomena discussed

(Netherlands) J J Lander, Surface Science, 1 (2), April 1964, !25-164.

4. Drag on an object in nearly-free molecular flow. The author studies the field of flow at a distance from the body roughly equal to the mean free path of the molecules. This is the region where departure from free molecular flow conditions becomes most marked. It is assumed that the distribution function for the gas is governed by the K r o o k equation with the additions of a point source term related to the shape of the body. An explicit expression for the drag is derived. M H Rose, Phys of Fluids, 7 (8), Aug 1964, 1262-1269.

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12. Absorption of hydrogen by silver-palladium alloys.

(USA)

The absorption of hydrogen from aqueous solutions by A g - P d electrodes increases with silver content at low pressures, but maximum solubility reached at high pressures decreases with silver content. (Standard pressure is that corresponding to the ~-/~ transition in the alloy.) The decrease in maximum solubility is probable due to a decrease in the number of available electrons in the band. (USA) A C Makrides, JPhys Chem, 68 (8), Aug 1964, 2160-2169.

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