Lubricant study in ultrahigh vacuum and in various gas environments

Classified

abstracts

445-459

31 445. Kinetics of degasification of liquid steel in vacuum. (USSR) The degasification rate of nonreduced ball-bearing steel in foils of different thickness can be described by an experimental diagram. The maximum characterises the effect of two contrasting factors, the decrease of bubbles during floating and the decrease of the interphase surface of the bubble origin. The degasification rate during boiling is higher than that taking place in the diffusion process with subsequent desorption at an uncovered metal surface. During evacuation of reduced steel by the decanting method a greater part of the gases separate from the boiling surface. 0 Kh Fatkullin et al, Sb Mosk Inst Stali i Splavov, No 41, 1966, 151-160

(in Russian). 37 : 41 of niobium in

446. Vacuum thermal expansion tester for investigations the 20 to 1,600”C temperature range. (USSR)

The device for measuring the elongation of Nb samples with dimensions diameter 6 mm x 150 mm at 1O-6 torr is described. The expansivity of Nb at the temperature range 20-1,600”C is Al&= -13.7 x 1O-5+68.5x lO~‘t+1.26x 10m9t3. B E Neymark and B R Brodskiy, %avodsk Lab, 32 (9)) 1966,1154-l 155 (in Russian) 447. Metallography of wrought temperatures. (USA)

vacuum-cast

beryllium

37 at elevated

Microstructural changes in wrought vacuum-cast beryllium at elevated temperatures were studied with a vacuum hot-stage metallograph. The phenomena of grain growth and the removal of mechanical twins from the microstructure were recorded with a 16 mm tine camera. V R Friehel, Rep RFP-544, Co Golden, Colorado).

Nov 1965 (Rocky

Flats Div Dow Chemical

448. Vacuum metallurgical

equipment and processes.

(Great

37 Britain)

A review is given of the characteristics of vacuum pumps available for processing work. T Thorley, Metal Treatment Drop Forging, 33, 1966, 123-141. 37 449. Variables affecting nitrogen removal in the vacuum-induction heating of iron- and Ni-base alloys. (Great Britain)

The basic thermodynamic considerations of the nitrogen reaction in Fe- and Ni-base alloys are discussed, and the literature is reviewed. The present investigation studies the nitrogen removal from alloys produced in a laboratory vacuum-induction furnace. A Simkovich,

J Metals,

18, 1966, 504-512. 37

450. Degassing metallic melts in ladle by vacuum treatment. (Great Britain)

After applying vacuum to a filled ladle until gas evolution seems to have stopped, the bubbling can be reactivated near the top of the ladle by dropping in a small amount of fine solid granules, of the same composition as the melt, for nucleation. Dortmund-Hoerder Huettenunion, British Patent 1,037,369 27th July 1966, 2 pages. 37 451. Clinkering of gas coal in a vacuum. (USSR) L P Bezuglyi and G G Rabukhina, Met i Koksokhim, (in Russian).

5, 1966, 3-11 37

452. Melting of iron, nickel and cobalt alloys in vacua. A review article. F Spemer, Tech Mitt, 59, 1966, 110-116 (in German).

(Germany)

37 453. Sublimation rates in vacua of PbTe and PbSnTe thermoelements. (USA) H E Bates and M Weinstein, Advanced Energy Conversion, 6, 1966, 177-180. isotopic gas analysis 38 454. Semicontinuous vacuum distillation and its application in the fabrication of very pure bismuth and selenium of rectifier quality. (Germany)

38.

Distillation,

organic

chemistry,

Semicontinuous vacuum distillation for refining of Bi and Se was investigated using a quartz apparatus. For distillation of Bi, temperatures from 950-1000°C were employed at a residual gas pressure of 122

10-a torr. The distillation of Se was carried out at temperatures below 350°C. S Richter and L Muller, Freiberger Forschungsh, 112b, 1966, 127-158 (in German).

39. Miscellaneous 455. Cold molecular

applications

39

welding study in ultrahigh vacuum.

(USA)

Cold molecular welding of typical metals which are being used or considered for the Apollo mission was studied. The coefficients of friction were determined for various metal combinations under specified conditions. The rating of the 45 metal combinations is based on static breakaway friction after 300 hr of contact and short time dynamic conditions. In addition to the ultrahigh vacuum tests for 45 metal combinations, the comparative effects of operation in air versus ultrahigh vacuum were determined for four metal combinations. The test apparatus used three pellets resting or being rotated on an annular wear track, with a 1000 psi contact pressure between the pellets and the wear surface. The design incorporated heaters for maintaining the wear surfaces at approximately 200°C. The coefficient of friction was determined by measuring the torque necessary to rotate the pellets. The mechanism was enclosed in a stainless steel chamber and evacuated with an oil-free vacuum pumping system capable of maintaining pressures in the 10e9 and lo-l0 torr range. C E Moeller et al, Rep NASA-CR-65390, Nov 1965 (Midwest Research Inst, Kansa City, MO). 39 456. Creep at elevated temperatures

and high vacuum.

(USA)

A series of high purity copper wires were creep tested in high vacuum at temperatures between 785” and 855”C, both in the argon bombarded clean state and after oxidizing in air at these elevated temperatures. It was found that the creep rate of the sample decreased noticeably after oxidation for about one hour between 400” and 500°C. The sample fractures in the oxidized state in test above 835°C. The largest minimum creep rate of the argon bombarded clean sample was about 0.1 per cent per minute, whereas that for the oxidized sample under the same stress of about 850 g/cm” was less than 0.2 per cent per minute. It is proposed that the creep phenomena can be explained with a model, in which oxide films act as dislocation barriers for dislocation. K Schroder et al, Rep NASA-CR-76088; SURI-MET-E-1189-566SA, May 1966 (Syracuse Univ Res lnst New York, Dept of Chemical Engineering and Metallurgy). 39 457. Determination of elevated-temperature fatigue data on refractory alloys in ultrahigh vacuum. (USA)

The results of fatigue tests conducted on molybdenum-base alloys at elevated temperatures in ultrahigh vacuum environments are reported. The specific material form of the TZM and TZC alloys (bar or plate), their heat numbers, and their chemical composition are given in a table. Typical microstructures of the TZC after annealing are shown, and fatigue curves are plotted as function of stress values. C R Honeycutt and J C Sawyer, Rep NASA-CR-54916, Jan 1966 (TRW

Equipment

Labs, Cleveland,

Ohio).

458. Automatic vacuum weighing apparatus decomposition kinetics of solids. (USSR)

for

investigating

39 the

The construction of an apparatus with automatic recording of the variation in weight of a substance is described. It consists of a quartz spring balance, a projecting device to present a magnified image of the lower end of the balance coil, and a photoelectric device to record the displacement of the lower end of the coil. A photosensor is connected in one arm of an electronic amplifier bridge. When the intensity falling on the photosensor is dismissed due to unbalance of the bridge, a reversing servomotor moves the photosensor out of the shadow zone. The stylus of the automatic recording device traces out the motion of the photosensor. The weight range is from 1 to 20 mg with an error of 1 x 1OMB g in recording a 30 per cent weight loss. V I Versohkm and V T Dis’menko, English Transl from Kinetika i Kataliz (USSR), 6 (61, 1965, 1121-1212, Rep NASA-TT-F-100 96, April 1966. 39 459. Lubricant study in ultrahigh vacuum and in various gas environments.

Wear and friction

characteristics

of lubricated

and unlubricated

Classified

abstracts

460-471

hardened stainless steel couples in sliding and rolling contact were studied in an ultra-high vacuum environment and in an UHV environment degraded by outgassing products known to exist in spacecraft. The lubricants were of the fluid, laminar film, and solid composite types. The UHV was degraded by high purity COa, 0, and H,O vapour. Results are compiled and presented in graphic form. The best overall lubrication was obtained with a Na,SiO* bonded WSe, laminar film, followed by chlorophenyl methyl silicone oil. The Hz0 vapour degraded UHV environment provided the most beneficial effect to lubricants. P H Bowen et al, Rep NASA-CR-65374,1966 (Westinghouse Electric Carp, Pittsburgh, Pa Research Labs), 39 460. Some influences of macroscopic constrictions on the thermal contact resistance. (USA) Accomplishments are reported in a theoretical and experimental study of some influences of macroscopic constrictions on thermal contact resistance in a vacuum environment. A numerical solution is given for the constriction resistance which removes the error present in an approximate analytical solution previously employed. The model is applied to the analysis of contacts between dissimilar metals and it was found that the model is capable of qualitatively predicting the resulting directional effect. A M Clausing, Rep NASA-74622: MF-TN-242-2, April I965 (Illinois Univ Urbana, Engineering Esperimental Station). 39 461. Melting, fabrication and creep testing of a 1.39 Ti-0.34 Zr-0.30 per cent Molybdenum alloy. (USA) The creep rupture strength values were determined. Depletion of carbon at the specimen surface was found to occur during testing in conventional dihusion pumped vacuum systems. Decarburization apparently occurs as a result of a reaction between residual oxygen in the vacuum system and carbon in the specimen forming CO. Testing in an ultrahigh vacuum utilizing a sputter-ion pump prevents decarburization. H F Conrad and P R Landon, Rep UCRL-14437, Nov 1965 (California Univ Livermore, Lawrence Radiation Lab). 39 462. Friction in ultrahigh vacuum. (USA) The design and construction of equipment for the investigation of friction behavior of single crystal surfaces in vacuum at 10-O torr is described. A special hydraulic system provides the motion for the specimens, which are cleaned by sputtering in the vacuum chamber. Techniques for growing Al single crystals are given. An appendix contains a brief review on the theories of dry friction. J Frisch et al, Rep UCRL-13190; MDd5-8, Sept 1965 (California Univ, Berkeley lnst of Engineering Research).

IV. Materials technology 40. Gases

and techniques

used in vacuum

and vapours

40 463. Ion-Molecule reactions of methane. The ionic reactions of gaseous methane were investigated in a tandem mass spectrometer. A description of this instrument is being prepared for publication in the Reviews of Scientific Instruments. The ion gun was a double-focusing spectrometer of nominally l/200 mass resolution. A differentially pumped collision chamber and a separate gas handling system for this chamber were used. An EMI Model 9642B 18-stage electron multiplier was used as the detector. The reactions of each primary ion were observed at 0.3 eV and several secondary-ion reactions were also studied. F P Abramson and J H Futrell, J Chem Phys, 45 (6), 15 Sept 1966, 1925-1931. 40 464. Thermal diffusion in Polyatomic gases: a generalized StefanMaxwell diffusi.m equation. (USA) Calculations are given showing the influence of inelastic processes on thermal diffusion in polyatomic gases, based on the Wang-ChangUhlenbeck-de Boer treatment of the Boltzmann equation, in which it is assumed that the distribution function for molecular spins is isotropic. Numerical solutions for several selected systems show that the effects of inelastic collisions on the thermal-diffusion factor are

not negligible and must be considered in deriving information on intermolecular forces from thermal-diffusion measurements, However, inelastic effects are not capable by themselves of explaining the anomalies in systems such as Ar-HCl and D,-HT. L Monchick et al, J Chem Phys, 45 (S), 15 Ott 1966, 3051-3058. 40 465. Configurational entropy of adsorption of large atoms. (USA) This is a theoretical article using Monte Carlo methods to compute the arrangements of atoms large enough to prevent adsorption on neighbouring surface sites for square and triangular surface lattices. It is shown that the adsorption behavior of such systems could be mistaken for nonlocalized adsorption. B G Baker, J Chem Phys, 45 (7), I Ott 1965, 2694-2697. 40 466. Continuum radiation in argon positive column. (USA) These studies show that the intensity distribution of the continuum (observed from 2900 to 7000 A”) does not correspond to that of a free-free, free-bound recombination spectrum. The continuum intensity, the 3Pa metastable population, and the relative populations of more energetic atomic states were examined as functions of pressure (5-30 torr) at constant currents and as functions of current (0.5-5 mA) at constant pressures. Details of the experimental apparatus are given. J F Prince and W W Robertson, J Chem Phys, 45 (7), I Ott 1966, 2577-2584. 40 467. Interaction of oxygen with hot tungsten. (USA) Studies of the reaction of oxygen at a polycrystalline tungsten surface over a temperature range from 1300°K to 2450°K for oxygen pressures from about lO-4 to lO-8 torr are reported. Pressures were measured with a mass spectrometer, care being taken to avoid errors due to spurious currents in a Bayard-Alpert gauge. The efficiency of removal of carbon impurity from tungsten, by heating in oxygen, was determined. Efficient removal occurs at temperatures above 2000°K and at pressures above lO-B torr. It was found that carbon monoxide could not be eliminated above 2000°K. An explanation is offered in terms of the interaction of atomic oxygen at the walls. J H Singleton, J Chem Phys, 45 (8)) I5 Ott 1966,2819-2826. 40 468. Coadsorption of oxygen and carbon monoxide upon a (110) tungsten surface. (USA) These studies show that a (I IO) surface of W that is covered by l/2 a monolayer of 0 atoms will adsorb about l/4 monolayer of strongly held CO molecules and about half as many weakly held molecules. These are half the amounts that can be adsorbed on a clean (I IO) face. The CO is desorbed in its original form in two states at about 450” and 1100°K and no COZ is formed. All of the 0 is removable at 1950”K, apparently as oxides of W. The composite O-CO covered surface is a disordered structure if formed at room temperature, but at about 1000°K a complex ordered surface is produced. Exposure of a bare (110) surface to CO2 at a pressure below lo-’ torr results in negligible adsorption. The apparatus has been described in previous reports, to which reference is made. J W May et al, J Chem Phys, 45 (7), I Ott 1966, 2383-2388. 40 469. Cbemisorption of Nitric Oxide on Tungsten. (USA) J T Yates and T E Madey, J Chem Phys, 45 (5), I Sept 1966,16231634. 40 470. Resolution of fine structure in ionization-efficiency curves. (USA) An energy-distribution difference method for determining ionization potentials and for detecting fine structureinionization-efficiencycurves is described, which eliminates the difficulties arising from the thermalenergy spread of the ionizing electrons. The retarding potential difference (RPD) method, developed by Fox et al, was used. This method resolves the fine structure of ionization-efficiency curves, presumably by reduction of the effective electron energy distribution. Ionization-efficiency curves are given for the inert-gas ions Ar+, Kr+, and Xe+, as well as the molecular ions CO+, N,+ and O,+. The results are compared with monoenergetic electron-impact data. R E Winters et al, J Chem Phys, 45 (6), 15 Sept 1966, 1931-1937. 40 471. Flash desorption and isotopic mixing of hydrogen and deuterium adsorbed on tungsten, iridium and rhodium. (USA) Flash desorption of hydrogen from tungsten, iridium and rhodium dosed at 100” and 300°K was investigated together with isotope mix-

123