Classified abstracts 169-181 analysis range product from a bath of steel of a standard analysis. Procedures have been developed to allow large carbon additions to the D H unit to produce a carbon steel suitable for the wire-drawing industry with properties at least as good as those obtained by the conventional "catch-carbon" techniques. I K Maelean and H G Trotter, Iron Steel Publn No 99 (Control ol composition in steelmaking), 1967, 199-205. 37 169. Electrophysical properties of inversion films formed on silicon under P and AI ion bombardment. (USSR) Si with resistivity of 4000 and 5000 ohmcm was bombarded by ions at 10-6 torr to form inversion films and subsequently annealed at 10 -5 torr. P+ ions with energy of 50 keV and quantities of 1 to 104 ~.C/cm = or A1+ ions with energy of 100 keV and quantities of I to 103 ~.C/cm = were used and the surface resistivity and Hall mobility of obtained films were measured. V K Vasii'ev et al, Fiz Tverd Tela, 9 (7), July 1967, 1905-1910 (in
Russian). 37 170. Induction heating and stirring of molten steel in ladles. (Sweden) A method of vacuum degassing is described in which the melt is heated and stirred by the same induction coil, located outside the ladle. The heat requirements are discussed and the various methods compared. Y Sundberg, A//manna Svensk Elec Akt J, 40 (2-3), 1967, 33-37. 37 171. Qualitative comparison of forgings from air-teemed and vacuum teemed ingots. (Italy) Stream degassed metal showed greater toughness and ductility, although micrographic and ultrasonic tests did not reveal appreciable differences. G B Boccone and R De Martini, Met Ital, 34, Feb 1967, 285-288, 290
(in Italian) 37 172. Vacuum degassed versus air melted steels: no clear-cut winner. (USA) Many materials engineers have reported good results by changing to vacuum degassed steels for critical electrical machinery, automotive and aircraft parts. Others feel that high quality air melted steels perform just as well. Examples in support of both viewpoints are presented but no firm recommendations are made. A F Hoenie et ai, Materials Eng, 65, April 1967, 78-81. 37 173. Preparation of high-purity niobium by thermal decomposition of niobium pentachloride. (USA) Distillation-purified niobium pentachloride was decomposed at 181 02000°C on 2-mil niobium wire which ultimately grew to 200 mils in diameter. Analytical data for the as-growth crystal bar indicated 16-19 ppm oxygen, 1 ppm nitrogen, 1 ppm hydrogen, 10 ppm aluminium, 60-160 ppm tantalum, and 10-190 ppm chlorine. Electron beam melting in a vacuum furnace produced samples with low recrystallization temperature and Vickers hardness of 42-48, fully annealed, The residual resistivity ratio of the vacuum melted sample drawn into wire form was p298°K/p10°K=311. L V MeCarty and W T Bachmann, Electrochem Technol, 5 (5-6), May-June 1967, 299-301. 37 174. Failure modes in nickel fatigued in vacuum, as a function of temperature and purity. (USA) Nickel specimens at two levels of purity were fatigue tested in vacuum of 5 × 10-7 torr and at temperatures up to 800°C. The nickel showed intergranular crack initiation and growth at low temperatures. An increase in temperature initially prolongs fatigue life due to a more homogeneous distribution of slip. With a further temperature increase the mode of failure undergoes a transition to intergranular crack initiation with concurrent recrystallization which results in a shorter life. The transition temperature varies with bending strain and specimen purity. R L Stegman and M R Achter, Trans Met Soc AIME, 239 (5), May 1965, 742-747. 52
37 175. Literature search on the manufacture of layers of molybdenum, tungsten, and rhenium by thermal decomposition of their earbonyls or reduction of volatile halides. (USA) Pure coatings of Mo, W or Re are advantageously deposited from the vapours of the fluorides (W, Re) or the chlorides (Mo, W, Re) by reduction with hydrogen. Details, conditions and results are discussed. M Kadner, Rep NASA-TT-F-I0914, May 1967, 12 pages, (Sci Tech Aerospace Reps, 5 (14), 2558, N67-27531). 37 176. Elevated temperature fatigue of TZC molybdenum alloy under high frequency and high vacuum conditions. (USA) High frequency fatigue tests were conducted in a high-vacuum environment on recrystallized molybdenum-base alloy TZC at temperatures between 1800 and 2200°F. The results indicate that in this temperature range no well-defined endurance limit existed. The application of a cyclic load to a statically loaded specimen produced a marked acceleration in the degree of specimen extension. C R Honeycutt et al, Rep NASA-CR-72241, May 1967, 28 pages, (Sci Tech Aerospace Reps, 5 (14), 2556, N67-27236). 37 177. Cleaning an ideal beryllium surface. (USA) A (001) plane of a Be single crystal is arbitrarily defined as an ideal Be surface. Requirements for cleaning this surface were established. It was found necessary to heat the crystal to 1000°C to produce a clean surface. Sputtering for 30 minutes with 1000 eV argon ions also cleaned the surface as well as the 1000°C heating did. R O Adams, Rep RFP-879, Feb 1967, 14 pages (Sci Teeh Aerospace Reps, 5 (14), 2542, N67-26836). 37 178. Analytical gas desorption apparatus. (USA) A chemical high vacuum system for the desorption and manipulation of desorbates from solid absorbents was developed. Essentially the system is provided with three sections for trapping the contaminants depending on their volatility. W H Toilver et al, Rep AMRL-TR-65-61; AD648516, Nov 1966, 17 pages (Sci Tech Aerospace Reps, 5 (14), 2472, N67-27004). 37 179. Study on the preparation and stability of uranium carbide samples for the determination of oxygen, hydrogen and nitrogen by fusion under high vacuum. (Spain) Variation in the oxygen, hydrogen and nitrogen content of uranium carbide was studied as a function of time and medium of storage (normal and argon atmosphere). The analytical method of high vacuum fusion in a platinum bath is described. M P Garcia, Rep JEN-170-dQ/1-60, Nov 1965, 14 pages (Sci Tech Aerospace Reps, 5 (14), 2480, N67-27326) (in Spanish). 39. MISCELLANEOUS APPLICATIONS 39 180. A head restraint device for vestibular studies. (USA) A restraint system based on a vacuum bladder technique was constructed from standard, commercially available materials. It provides a degree of restraint comparable to that available with permanent, rigid head/torso molds individually fitted to each subject without the attendant costs in preparation time. W Carroll et al, Rep NASA-CR-83949; NAMI-992, Jan 1967, 10 pages (Sci Tech Aerospace Reps, 5 (13), 2236, N67-25968).
IV. Materials and techniques used in vacuum technology 42. GLASS, CERAMICS AND REFRACTORY OXIDES
42 181. Chemical strengthening of ceramic materials. (USA) An investigation of the effect of compressive surface layers on the strength of polycrystalline ceramic bodies is described. Low expansion surface layers were formed on conventional ceramics by chemical re-