Ultrasonic measurements of elastic moduli of polycrystalline tantalum and niobium

Ultrasonic measurements of elastic moduli of polycrystalline tantalum and niobium

measurements of elastic moduli of polycrystalline tantalum and niobium. Applied Materials Research, 3, No. 3, p. 138 (1964) Absolute values of the vel...

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measurements of elastic moduli of polycrystalline tantalum and niobium. Applied Materials Research, 3, No. 3, p. 138 (1964) Absolute values of the velocity of longitudinal and elastic waves in the low megacycle frequency range were measured by a resonance method on prismatic rods of tantalum and niobium specimens in the temperature range lOO-300°K. The results have been used to compute Young’s modulus and shear modulus and it has been shown that these materials are not isotropic. In order to obtain true elastic moduli from acoustic velocity measurements a correction given by Bradfield for the anisotropy of the specimen has to be applied. (4 tables, 5 figures, 14 references) (Ultrasonics 1964, abstract

D. c. B.,and LUMB,R. F. Piezoelectric probes for immersion ultrasonic testing. Applied Materials Research, 3, No. 3, p. 176 (1964) A theoretical and experimental investigation of probe characteristics has been made to find the most suitable transducer material and the best manufacturing conditions. In addition to its ability to withstand immersion, lead zirconate titanate has the highest loop gain and is therefore most suitable for a combined transmitting and receiving probe. If a separate receiving probe is used, quartz or lithium sulphate may have some advantage. Probe characteristics, electrical tuning, collimation and focussing are discussed by reference to particular problems, and it has been found that line focussed probes of 1 in focal length are the most suitable. (8 figures, 4 tables, 8 references) WALKER,

PALMIERI, L. UltrasoBic

277)

(Ultrasonics

1964, abstract 281)

PETERS, B. F.

An ultrasonic method for evaluating bonds in large metallic bearings. Materials Evaluation, 22, No. 6, p. 257 (1964) A double transducer probe working at 2.5 MC/S was used to evaluate the quality of bonds between a tin-based babbit and a steel block such as are used in large bearings. The method consists in comparing the relative intensities of two echoes, one due to reflection from the interface, the other due to reflection from the back wall. The greater the relative difference between echoes, the better is the quality of the bond. It appears that an approximate percentage of bonding can be established by this method either by comparison with known standards or from the history and geometry of the specimen. (9 figures) (Ultrasonics 1964, abstract 278)

WILLOCKS,J., etal.

Foetal cepbalometry by ultrasod. and Gynaecology

Journal of Obstetrics of the British Commonwealth, 71, No. 1,

p. 11 (1964) An ultrasonic method of determining the size of the foetal head and by repeated measurements following the growth of foetus in utero is described. The accuracy is thought to be to within 1 mm and this is confirmed by postpartum caliper measurements. The ultrasonic method has the advantage over X-rays of being more accurate and free from radiation hazards. A portable commercially available unit operating at 2) MC/S with a single probe placed on abdominal wall and manipulated until maximum reflection is obtained is all that is necessary. Measuring the time interval and knowing the velocity of ultrasound in brain tissue gives the required information. (7 figures, 2 tables, 29 references) (Ultrasonics

1964, abstract

282)

SMITH, 1. L., and FULLER, A. G.

Measurement of chill depth on cast iron test pieces and rolls. British Cast Iron Research Association Journal, 12, No. 3, p. 319 (1964) Results of experiments carried out to determine the feasibility of measuring the depth of chill and chillplus-mottle by ultrasonic methods are described. A standard ultrasonic llaw detector working at 2-S MC/S with twin barium titanate probes was used in conjunction with a delay line to measure the time between introducing ultrasonic energy into the material and its return from the mottled zone. The results obtained show that ultrasonic estimation of chill depth is practicable but the estimation of the depth of chill-plus-mottle needs further experimental work. (8 figures, 5 tables) (Ultrasonics 1964, abstract 279)

WAKEFIELD, G. Ultrasonic diagnosis

in cerebral

diseases. University College Hospital Magazine, 47, No. 4, p. 10 (1964) A basic definition of ultrasonic principles is followed by a discussion about the source of midline echo and the procedure for examination. Apart from midline it is also possible to record echoes from lateral ventricles, subdural and extradural haematomas, tumours and hydrocephalus. A number of case histories are discussed and their ultrasonic diagnostic results illustrated. The method is simple, quick, and causes no discomfort to the patient and, as has been confirmed by other studies, the ultrasonic method is accurate in well over 90% of examinations. (6 figures, 4 references) (Ultrasonics 1964, abstract 280)

WILSON,

W. E.

Ultrasonic washer speeds street light cleaning. Electrical World, 161, No. 10, p. 55 (1964) This is a short description of a small specially designed self-contained truck used for washing street lights. Two men can change and wash 65-85 globes a day with excellent results. It contains a petrol driven power generator, cleaning tank, re-circulating pump and filters, heating and drying equipment and eight immersible ultrasonic transducers. It takes about 2 min to clean a very dirty globe. (3 figures) (Ultrasonics 1964, abstract 283)

Ultrasonic welding. Machine Design, 36, No. 9, p. 130 (1964) A comprehensive paper based on selected chapters from a forthcoming book describes the production of true metallurgical bonds in the solid state without altering the mechanical or metallurgical properties of the materials. By proper adjustment of clamping force, power level and welding time, bonds of 65-100°A of the strength of the parent metal can be made. This machine is ideally suited to welding thin materials, but on larger machines aluminium sheet of up to 0.120 in can be welded economically. A number of graphs and tables show the superiority or even dominance of ultrasonic methods in many applications. (9 figures) (Ultrasonics 1964, abstract 284)

LJLTRASONICS/~~~~~~~-December1964