779. Sublimation of strontium sulphide and dissociation energy of SrS

Classified

abstracts

774-179

study can be made of the effects of grinding variables on the strength of ceramics. The performance of the equipment is evaluated and a number of work procedures are established. R Sedlacek and E P Farler. Rep AD-654209. A4av 1967. 53 .na~~e.s ._ (Sci Tech Aerospace Reps, 5 (22); 4077, N67-37262): 42 774. An investigation for fabricating and evaluating the properties of chemically vapour deposited alumina and magnesia. (USA)

The chemical vapour deposition technique for aluminium oxide was investigated using the reaction of aluminium chloride and water to give alunlina and hydrogen chloride. Transparent, theoretically dense, alpha-aluminium oxide was produced. If the pressure or deposition rate was increased, the product became white and opaque due to the inclusion of many small voids. Both isotropic and anisotropic aluminium oxide could be produced, depending on process conditions. R C Ellis, Rep S-946; AD-655585, April 1967, 73 pages (Sci Tech Aerospace

Reps, 5 (22), 4077, N67-37254).

45. SOLDERING,

WELDING,

BRAZING,

See abstract

vacuum apparatus.

number 717. 45

775. Material

transport and temperature melting aluminium electrodes. (USA)

distribution

in arc between

The following processes are of decisive importance for the properties of high-current arcs of the types used in welding techniques: (1) the gas and plasma transport in the arc caused by thermal convection and by the hydromagnetic pumping effect (known as plasma jet); (2) the metal transport in the state of droplets and vapour between the electrodes; (3) the energy transport between the different arc regions brought about by gas and plasma streaming, heat conduction, and radiation, (4) the distribution of heat generation within the arc: (5) the processes in the transition regions between the arc plasma and the metal electrodes. Some observations cn an arc of the type used in the MIG (metal inert gas) welding is presented. (Sweden) E A Smaers and K Acinger, Rep 67-06, Cold Phenomena in Ionized Gases, Vienna, April 4120, N67-37798). 776. Method

1967, 5 paKes (Sri Tech Aerospace

of joining

molybdenum

leads

to copper

Reps, 5 (22), 45 :37 conductors.

(USSR) A simple and convenient method of joining molybdenum leads to copper, copper-alloy, silver, and steel conductors is described. The molybdenum leads are cleaned mechanically, degreased, washed in water, and copper-plated electrochemically, using a copper sulphate solution free from cyanide and a current density of 3 A/dm2. After copper-plating, the leads are washed in running water and coated with ordinary lead-tin solder; they can then easily be soldered to the copper or other metal conductors. If necessary, repeated solder coatings may be applied to facilitate junction. S N Kolesov et al, “Reliability of the operation of teleco~~~tnunication.r systems and the development and Kazakhstan”, Tashkent,

3rd Nov 1966. 47. OUTGASSING

PRESSURE

TERING

DATA, VAPOUR DATA, RESIDUAL GASES

IN VACUUM

RESIDUAL

SOLDERS 45 :31

Solder for electronic

46 777. System for tinning ceramic objects. (USSR) The general characteristics of types of equipment used for tinning ceramic objects directly in molten solder under the influence of ultrasonic vibrations are described. Such systems contain a heating element and an ultrasonic source but cannot treat objects of complicated shape. A new system is here proposed in order to remedy this lack. This is achieved by having a heating element with a solder bath inside it, the bath being connected to the source of ultrasonic vibrations and incorporating a piston and reservoir. For tinning a plane ceramic object the latter is held to the working surface for 5-10 set under ultrasonic vibration, the amplitude of the vibrator being 1-3 p. Individual regions left untinncd because of buckling may be rectified later. A S Shilyaev et al, USSR Patent 187,601, Appl 24th Feh 1964. Pabl

of these in the Republics of Central “Fan”, 1967, 166 (in Russian).

Asia

47

(USA) The vapour pressure of holmium was measured from IO x to 10-j torr using modifications of the Langmuir and Knudsen methods. A tubetype orifice permitted use of the Knudsen method at the higher pressures with suitable corrections. Lowest pressures were measured using a graphite condenser surrounding a large Langmuir sample, with the vapourized metal being trapped as the nonvolatile carbide. Relationships between vapour pressure and temperature are proposed. G F Wakefield et al, J Clrenl Pltys, 47 (12). l5rh Dee 1967, 49944999. 47 779. Sublimation of strontium sulphide and dissociation energy of SrS. 778. Vapour pressure of holmium.

(USA)

The sublimation of strontium sulphide in the temperature range 1543 to 2122°K was studied by mass spectrometric and vacuum balance efiusion techniques. Partial pressures of the vapour species Sr, S, S, and SrS were derived. Results are compared with those of Marquart and Berkowitz and of Colin, Goldfnger and Jeunnehomme. Heats of reaction are given. E D Cater, J C/X/~ Phys, 47 (12). 15th Dee 1967. 5353-5357.

VI. Miscellaneous 62. EDUCATION, Versatile

TRAINING,

vacuum apparatus

LECTURE

306

DEMONSTRATIONS

for student practical

62 : 20 work. See abstract

number 658. 63. DOCUMENTATIONS. Computer experiments plasmas: a classification

ABSTRACTS,

BIBLIOGRAPHIES

63 : I8 with charged particles. Charged Huids and and bibliography. See abstract number 643.

63 : 23 See abstract number 685.

AND CERAMIC-

63 : 30 Semiconducting

46:31 Evaluation tests of a low-sinter-temperature process. See abstract number 715.

ceramic

SYSTEMS,

GAS ANALYSIS

Beryllium mirrors at cryogenic temperatures.

46. GLASS BLOWING, GLASS-TO-METAL TO-METAL SEALING TECHNIQUES

DATA, GET-

thin films; an annotated

bibliography.

See abstract

number 705.

metallizing

63 : 33 Bubble chambers bibliography;

Supplement 1. See abstract number 721.