摘要:

An x‐ray diffraction stage has been constructed which allows following structural and precise dimensional changes simultaneously as a function of temperature. It also permits manual (tensile) straining of samples,insitu, at any point in a phase transformation sequence (temperature/phase‐structure) to examine the interplay between stress (or strain), temperature variation and phase transfromation behavior.

ISSN:0034-6748    

DOI:10.1063/1.1136058

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Two dielectric spectrometers for use at sub‐audio frequencies have been designed around a digital microcomputer and data acquisition system. In one technique the driving signal and the current response are harmonic. In the other technique a current transient results from a voltage step. Comparison of the two techniques on real materials reveals good agreement between complex relative permittivity spectra. Moisture and electrode polarization aspects of specimen preparation are addressed.

ISSN:0034-6748    

DOI:10.1063/1.1136059

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Both coherent and random short duration electromagnetic noise source pose serious problems to meaningful acoustic emission studies. A simple but effective discriminator is described which makes acoustic emission studies possible in severe noise environments. Additional circuitry is presented which permits one to eliminate coherent noise sources from the acoustic emission data.

ISSN:0034-6748    

DOI:10.1063/1.1136060

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A design of simple clamp type pressure apparatus utilized for measurements of magnetic susceptibility and electrical resistivity at low temperatures is presented. The cell consists of WC piston and Be–Cu cylinder which was autofrettage processed, and sample cavity consists of a teflon bucket and an electrode plug. In a temperature range from 300 K down to 77 K, pressure was determined by manganin gauge which was calibrated by Bi I→II transition pressure at room temperature and also the temperature dependence of pressure coefficient of manganin resistance was taken into account. As a result, the cell was capable of generating hydrostatic pressures up to 30 kbar at room temperature and at least up to 25 kbar at 4.2 K.

ISSN:0034-6748    

DOI:10.1063/1.1136061

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple optical cell for high‐pressure studies of liquids and solutions to 5 kbar, and used in the 0–60 °C temperature range, is described. Convenient methods for pressure measurement, temperature control and isolation of the sample from the pressure fluid are presented. This system is used to detect liquid‐solid phase transitions in benzene and trans‐decalin by scattered light measurements.

ISSN:0034-6748    

DOI:10.1063/1.1136062

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The conceptual design and construction of an apparatus developed for deforming materials by subjecting them to constant compressive stresses at elevated temperatures is described. Sample loading and alignment procedures and performance capabilities are discussed. A computer controlled data acquistion, storage and manipulation system is also described.

ISSN:0034-6748    

DOI:10.1063/1.1136063

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A strain gage transducer system has been developed which functions as ’’electronic calipers’’ to measure changes in thickness of samples as they are compressed in an opposed diamond‐anvil optical cell. Planimeter measurements on photomicrographs of the same samples determine area changes and ruby fluorescence techniques provide pressure measurements. These techniques permit direct volume change measurements to be performed in the diamond cell. Accuracies inv/viof 1% or better provide experimental PVT data to assist in developing equation of state models for explosive materials.

ISSN:0034-6748    

DOI:10.1063/1.1136064

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

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 104or 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 effects 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.

ISSN:0034-6748    

DOI:10.1063/1.1136065

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A new experimental technique has been used to study the evaporation rates of complex hydrocarbon oils with low ambient vapor pressures. This technique follows the evaporation of an oil film on a piezoelectric quartz crystal in vacuum. Reasonable agreement is found between vapor pressure measurements of dioctylphthalate at 25 °C by this technique and values reported in the literature. Experimental evaporation rate data at 25 °C by this method are also given for four complex oils; No.2 diesel oil, ’’100 pale oil’’ and two crude oils.

ISSN:0034-6748    

DOI:10.1063/1.1136066

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Evolution of ferrofluid contained in two vacuum rotary feedthroughs is studied for the first time by a time‐of‐flight mass spectrometer in order to provide information on the background material these seals introduce into a high vacuum system. The seals used diester and poly(phenyl ether) based ferrofluids. The rate of evolution of the diester was found to be of the order of 3×10−10g/s and that of the poly(phenyl ether) was below the detection limit of the mass spectrometer, i.e., 10−10g/s. The oxygen and water evolution, which are generally of prime interest in vacuum application, were found to be 10−9g/s for both seals at 3,000 rpm. The feedthroughs were successfully employed in precision abrasion mass spectrometric experiments.

ISSN:0034-6748    

DOI:10.1063/1.1136067

出版商:AIP    

年代:1980

数据来源: AIP