Measurements of diamond strength at high temperatures

Measurements of diamond strength at high temperatures

Classified abstracts 2000-2010 wrar experiments were conducted with the various materials used in lubrication systems in vacuum. The results indica...

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Classified

abstracts

2000-2010

wrar experiments were conducted with the various materials used in lubrication systems in vacuum. The results indicated that while relatively high rates of evaporation are obtained for conventional oil and grease lubricants, these materials may be effectively utilized if concepts such as molecular flow seals are used to reduce evaporation losses. For prolonged exposure to vacuum environment many inorganic compounds and soft metal films have potential usefulness. With conventional lubricants, degassing of the fluid can present a problem. The results of sliding friction experiments in a vacuum environment indicate that there are basic metallic structures which have markedly superior friction characteristics. U H Buckley. Ren NASA-TM-X-52284. Mat, 1967 (NASA LFI(.;s Research Ce/;tcr. i‘leveland. Ohio). 23 : 20 2000. A vacuum chamber for nuclear scattering experiments. (Nethcrlands) A 24 in diameter scattering chamber of the sliding strip type with a 3 in by 153 slot for use with a double focusing magnetic spectrometer is described. Relative to earlier published designs there are two improvements: the vacuum seal is reliable whether the strip is moving or stationary and the slot is considerably higher. The basic features of these improvements are described. (Great Britain) F L Borsay, Nlrct Instrum Methods, 52 (2), June 1967, 338-340. 25. BAFFLES,

TRAPS

Photomultiplier

cooling

26. AUTOMATIC

AND

REFRIGERATION

apparatus.

PROTECTIVE

See abstract

EQUIPMENT 25 : 33 number 2062.

AND CONTROL

EQUIPMENT

26 2001. Automatic device for periodical pumping vacuum systems. (USSR) A device is described for pumping a system with low leakage by a mechanical pump. A stop-cock between the pump and the system is motor-driven and when the stop-cock is closed the pump is switched off. The device was used for pumping a system where the pressure rose from 2.6 x IO-* to 3.5 x 10m2 torr during 50 minutes. V K Gorshkov and L N L’vov, Zuvodsk Lab, 33 (8). 1967, 1029-1030 (i/r R~rs~im). 26 2002. Cryostats for the temperature range --30” to -160°C. (East Germany) The cryostats described, are based on the cooling action of liquid nitrogen contained in a Dewar, and the heating action of an apropriate heating coil. A gas thermometer with mercury column controls the connection of the heating coil. This system is able to maintain a cooling bath containing methyl alcohol, ethylbromide or other suitable liquid at the required temperature, with an accuracy of about f 1.5’C. E Reissig. E.~-ppv Trc~/~P/~.Iw, 15 (I). 1967, 47-50 (in Germarl).

27. LEAK DETECTORS

AND LEAK DETECTION

Special treatment reduces helium permeation systems. See abstract number 2095.

of glass

27

EQUIPMENT

liquid leak

AND THERMOMETERS

28 : 64 2004. Electric resistance furnaces and drying chambers. (Czechoslovakia) The design of all types of resistance heated furnaces and drying chambers is described. Vacuum furnaces and drying chambers are mentioned only briefly and with many errors so this book cannot be recommended io desikners of vacuum systems. M Dolejsi and V Tomek, hook published by SNTL, Praha, 1967, 352 pages, price Km 31 (in Czeclt-original title: Elektricke odporove pece a susar~~~~). 676

2008. Temperature

measurement

in

high

temperature

chemistry.

(France) The precision and accuracy obtainable with common temperature measuring instruments are reviewed and the newer instruments such as the photoelectric pyrometer are described. The principal limitation is their unusability under ideal conditions. Higher accuracy would be possible if the experimentalist had additional internal checks, such as internationally recognized secondary reference points. R F Walker, Rev Intern Hurctes Temp Refrnctaires, 3, 1966, 301 308. 28 2009. Plasma resistance furnace. (USA) A new type of furnace is described, in which argon gas Ilowing through refractory lining is ionized by an electric arc to form a plasma that heats the specimens. Chamber temperatures up to 4500°F were achieved with zirconia insulation, in furnaces of 5.2 kW. E R Werych and R Rauschenberger, Res/Develop. 18 (7). 1967. 26. 27.

27 : 42 in vacuum

2003. Vacuum tightness in cryogenic tanks. (USA) Tests of leak tightness of double wall vessels for storing oxygen and nitrogen are described. Helium mass spectrometer detectors were used. R J Roehrs, Metal Progress, 91 (4), Apr 1967, 85-88.

28. HEATING

2x : 42 2005. Measurements of diamond strength at high temperatures. (USSR) The design of a high vacuum apparatus for measuring the microstrength of high-melting point materials at temperatures up to 1400-C at pressures of 6x lO-8 torr is described. Using this apparatus the strength of diamond was measured in the temperature range 800 to l39O”C, where the value of the microstrength is falling from 7200 to 1440 kg/mm?. Surface graphitization of diamond was not observed at temperatures below [email protected] and a graphitized surface layer of I to 2 pm was grown on diamond heated to 1390°C at 6 IO ~* torr for IO min. T N Loladze et al, Zarodsk Lab, 33 (8). 1967, lOO5- 100X(irr R~wiun). 2x 2006. A technique for accurate specimen temperature measurement in a thermobalance. (Great Britain) A method is described, which is based on the principle of using electrically conducting planes and knife edges to form the conducting path from the thermocouple junction to the measuring instrument. Construction difficulties are discussed. E J Chatfleld, J Sci Instrum, 44 (0, Au.g 1967, 64%65 I. 28 : IX 2007. On heating gases with non-constricted electrical discharges. (Great Britain) The non-constricted discharge heaters are analyzed, the advantages of heaters of this type are discussed and a number of examples of their uses are cited. Discharges in the absence of magnetic field are discussed first. A method of calculating the fraction of the gas flou directly heated by the discharge and the mean temperature that it attains is presented in terms of parameters that are easily measured experimentally. Then. heaters based on magnetically rotated arcs arc discussed, and the conditions necessary for the uniform heating of the emerging gas are considered. A method of estimating whether these conditions are fulfilled in any given circumstances from measurements of the rotational frequency and visible diameter of the arc. i\ presented. J Lawton, Brit J .4pp/ Plrrs. 18 (8). 1967. IO95 1103.

III.

Vacuum

30. EVAPORATION

applications AND SPUTTERING

30 (USA) 2010. Resistivity and structure of C‘r-SiO cermet films. The structure, resistivity, and temperature coefficient of resistance (TCR) of Cr-SiO films with controlled compositions from 0 to 50 atomic per cent SiO have been investigated. Randomly disordered films condense at - 196°C. Higher temperatures introduce varying degrees of order accompanied by disproportionation of SiO and reaction with Cr. This leads to nonhomogeneous structures consisting of amorphous SiO, and Cr-Si phases according to the binary diagram. Metallic narticles of +Cr and Cr,Si, with either little or no longrange order or at the most partially crystalline, provide conductivity which decreases with increasing SiO, concentration. The resistance decreases during annealing are proportional to the Cr,Si concentration over a wide composition range. The TCR’s of highly disordered films are negative and shift toward positive values upon annealing. Their interpretation requires metallic and thermally activated