Method for measuring evaporation rates of complex oil mixtures with low ambient vapor pressures

Classified

abstracts

4608-4618

should be a good secondary emitter as well as a good semiconductor. We herewith report a new combination (SnO, + Ai,O,) for use as continuous dynodes. SnO, acts as a semiconducting material and Ai,O, as a secondary emitter. The advantage of this combination is that the resistivity of the SnO, film Increases due to the presence of AI,O,. (India) P W Mahajan and S V Bhoraskar, J Vat Sci ~ec/tno/, 17 (6). 1980, 1376-1377. I? 4608. A microwave-induced emission spectrometry.

plasma

as an excitation

source

for

atomic

(Netherlands) A microwave-induced plasma (MIP) is one of the excitation sources that have been investigated during the last 10 or 20 years for their usefulness in elemental analysis by means of atomic emission spectrometry. With the resonant cavities used until recently it was necessary to take special precautionary measures for generating the plasma and for maintaining it while introducing a sample for analysis. The authors have designed a resonant cavity in which the microwaveenergy is transferred to the plasma more efficiently, resulting in an MIP that is more easily generated and more stable, and can be used for a wider range of analytical applications. C I M Beenakker et al, Philips Tech Rer, 39 (3/4), 1980, 65-71.

22. GAUGES

AND

MEASUREMENT

22 New

high

sensitive

4614. Construction prefilter. (USA)

J H Craig

apparatus

and

micromanometer.

performance

Jr and

J L Hock,

AND

PUMP

A 20 K cryopump with a high conductance baffle design. (GB) Tocreate better vacuum conditions in the central region ofour cyclotron a 20 K cryopump has been designed and built with a 100 K baffle optimized for a high conductance and a low radiation input. The transmission of the baffle is 0.5, the pump speed is 8000 I s-’ for nitrogen. The design techniques and the results are described. (Netherlands) 0 C Dermois and P W Schmidt, Vacuuni, 30 (10). 1980, 411-414.

4610. Removal of volatile materials from forepump oil. (USA) The removal of condensable vapours from vacuum forepumps may be achieved by bubbling air through the oil .reservoir of the forepump. This removes the volatile material from the oil, allowing continuous pumping of materials by non-vented pumps that would otherwise require frequent shutdowns for oil changes. There is also an increase in the elTective pumping speed for these materials, as well as a saving of pump oil. Sci

Technol,

17 (6).

1980.

The appropriate

4612. Method low ambient

test domes

for measuring vapor pressures.

for

evaporation

pumping

rates

speed

of complex

measurement.

oil mixtures

with

(USA) A new experimental technique has been used to study the evaporation rates of complex hydrocarbon oils with low ambient vapour pressures. This technique follows the evaporation of an oil film on a piezoelectric quartzcrystal in vacuum. Reasonable agreement is found between vapour pressure measurements of dioctylphthalate at 25’C by this technique and values reported in the literature. Experimental evaporation rate data at 2s”C by this method are also given for four complex oils: No. 2 diesel oil, ‘100 pale oil’ and two crude oils. S H Baek et al, Ret Sci Insrrum. 51 (lo), 1980, 1366-1399. 210

details are presented for a low-cost energy is made between two devices of different of the longer device is shown to be 0.5 eV at J Vat

Sci

TechmA,

I7 (6).

1980.

1360-1363.

VACUUM

VALVES,

BAFFLES

AND

TRAPS

(USA) A rotary-valve gas pulser that produces a pulse-modulated seedant gas for mixing with a steady flow carrier is described. J M Madeson and E A Theby. Rer Sci Insrrum. 51 (10). 1980. 1416-1420.

4615.

Rotary-valve

gas pulser.

25. HEATING

EQUIPMENT

AND

THERMOMETERS 25

4616. (USA)

Design

for

a high

temperature,

high

vacuum

evaporation

furnace.

An evaporation furnace capable of temperatures greater than 1700°C in high vacuum, with temperature monitoring, is described. The assembled furnace can be inserted through a standard 2.75 in. vacuum flange. K W West,

J Vat

Sci

Techno/,

17 (6).

1980,

1382-1384.

1384.

21 (GB) The current test domes for pumping speed measurement with two gauges and a calibrated orifice have been reviewed. The key to investigation of test domes is IO choose a suitable assumption characterizing the inlet aperture of the pumps. In order to set up an appropriate test dome instead of an infinite one, first we should determine the height of the lower chamber of thedome, then determine the gauge position for pressure measurement. A set ofequations that show the relation between the height, the position and the radius of the calibrated orifice have been derived, and solved by the Monte Carlo method. The heights and positions of appropriate test domes have been obtained for three orifices of diflerent radii. The check shows that in appropriate test domes the same pressure appears in three main directions, and therefore simulates infinite test domes more perfectly than ones as given in the tentative standard ISO/DlS 3556/l and others. (China) F Yu-guo and X Ting-wei, Vacuum, 30 (10). 1980. 377-382. 21 4611.

22 energy

cost

23

4609.

J Vat

of a low

FLUIDS 21

P P Nicole,

characteristics

and auxiliaries 23. PLUMBING,

21. PUMPS

PRESSURES

(USA) An instrument is described where the downwards or upwards displacement of menisci under the action of a pressure differential in a U-tube arrangement is magnified by a factor of IO’ or more. This is accomplished by determining the volume of manometer fluid displaced via the very precise observation of motion of an air bubble inside a horizontal capillary tube connecting the large and equal diameter vertical legs of the manometer. Means of introducing and initially placing the air bubble are described as well as the use of a long capillary spirally coiled in one plane. This plane does not need to be placed horizontally because buoyancy forces cannot influence the bubble displacement. An instrument has been built and checked for surface tension etTects which proved to be negligibly small. The instrument was used to measure velocity distribution of air flowing laminarly through a tube. The agreement between data and theory is excellent. W Leidenfrost and J Ku, Rev Sri Insrrwn, 51 (IO). 1980. 1363-1365. 4613.

Construction and performance filter (Bessel Box). Comparison lengths. The energy resolution a pass energy of 6 eV.

II. Vacuum

OF LOW

Ill. Vacuum

applications

31. SPUTTERING 31 (USA) The silicides of molybdenum have been formed by cosputtering mixtures of molybdenum and silicon on oxidized silicon wafers. Alloys with asdeposited Mo/Si nominal atomic ratios of 0.25 to 4 were sintered in a hydrogen ambient in the temperature range of 900-1150°C. The formation of the silicide in these films was followed by the use of sheet resistance, by X-ray diffraction and stress measuring techniques, and by the use of transmission electron microscopy. The resistivity was found to decrease with increasing molybdenum content, the lowest being -60 pn cm. The stress was highest in films richer in the intermetallic MoSi,. The coexistence of the three phases MosSi, MosSi, and MoSi, led to lower stresses due to void formation in the film. A comparison of the resistivity and the sintering behaviour in MoSi films has been made with that observed in Ta-Si and Ti-Si films. The role of the oxygen contamination has been emphasized as one of the rate controlling factors in the silicide formation. S P Murarka et al. J Appl Ploys, 51 (lo), 1980, 538&5386. 31 4617.

Cosputtered

molybdenum

4618. AESstudy oftin-lead surface composition and

silicides

on thermal

alloys:eff~tsofionsputteringand structure. (USA)

50,.

oxidationon

Using Auger electron spectroscopy, we have investigated the surface composition of a 60:40 soft solder (72a/oSn-28a/oPb). the effect of ion sputtering on the composition and structure of the surface and the