WorldCat Identities

LEXINGTON LABS INC CAMBRIDGE MASS

Overview
Works: 7 works in 13 publications in 1 language and 13 library holdings
Publication Timeline
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Most widely held works by LEXINGTON LABS INC CAMBRIDGE MASS
Feasibility of forming refractory fibers by a continuous process( Book )

4 editions published between 1963 and 1964 in English and held by 4 WorldCat member libraries worldwide

Methods for continuous formation of refractory fibers, or whiskers, by vapor phase growth are under investigation. The vapor phase processes are: (a) aluminum halide oxidation and (b) aluminum oxide reduction and recrystallization. Preliminary experimentation with the halide system at temperatures around 1200 C indicates that in order to obtain continuous fiber production, it is essential to (a) control the supersaturation, (b) control the temperature, and (c) probably provide suitable nuclei for crystal growth. (Author)
VAPOR PHASE GROWTH OF RUBY MONOCRYSTALS( Book )

3 editions published between 1966 and 1967 in English and held by 3 WorldCat member libraries worldwide

Ruby monocrystals were produced by vapor phase growth using chromium organometallic compounds as the chromium dopant ion source. The low decomposition temperature of these compounds prevented high dopant homogeneity and sufficiently long growth runs to be successfully conducted. Growth furnace modifications were made which should enable three inch long by 3/8 - 1/2 inch diameter crystals to be grown having their longitudinal axes perpendicular to the impinging reactant gas stream. Other modifications were incorporated into the growth system which should enable continuous runs up to 100 hours duration, elimination of some of the problems of non-uniform dopant homogeneity and secondary nucleation, and further improve crystalline purity. (Author)
Evaluation of vapor deposition growth of oxide single crystals from metal halides( Book )

2 editions published between 1964 and 1965 in English and held by 2 WorldCat member libraries worldwide

Preliminary investigations to determine significant vapor growth parameters were completed. Growth rate, substrate orientation and temperature, reactant vapor velocity, total pressure and partial pressures of the reactant gases were shown to influence the kinetics of crystal growth from the vapor phase. A two-inch diameter, molybdenum-element, muffle furnace was completed, which will enable growth of oriented ruby and sapphire crystals at least one inch in diameter. An experimental activation energy of 3.25 ev was determined for the overall growth process. A mechanism other than gaseous diffusion appears to be dominant for this system. Laminar flow, in the growth zone, is indicated by a calculated Reynolds number of 13.5. Vapor grown ruby and sapphire crystals exhibited a dislocation density reduction of one to three orders of magnitude over the flame fusion substrates. It was observed that dislocation densities decreased with increasing thickness of vapor growth. (Author)
Investigation of a high temperature electrical conductivity device for use with thermal image heating( Book )

1 edition published in 1964 in English and held by 1 WorldCat member library worldwide

The 'double-clamshell' imaging system has been successfully used to measure electrical conductivity of single crystal and polycrystalline aluminum oxide and pyrolytic boron nitride in the absence of impressed electric and magnetic fields. A furnace with a controlled atmosphere was designed and constructed for the conductivity measurements up to a temperature greater than 2130K. Two-5000 watt xenon arc lamps were used for energy sources. At 1500K a temperature gradient of 6 deg K along the empty furnace axis was measured with alumina-shielded thermo-coupcouples. The thermal conductivity of a sample reduced the gradient to less than 1 deg K. (Author)
Rubies for reference temperature standards( Book )

1 edition published in 1966 in English and held by 1 WorldCat member library worldwide

The vapor-phase growth technique was further developed for the growth of sapphire and ruby single crystals. Impurity content below 3 ppm was attained. Electron-microprobe technique was improved and used to demonstrate chromium doping uniformity of plus or minus 5ppm. (Author)
Determination of the feasibility of forming refractory fibers by a continuous process( Book )

1 edition published in 1966 in English and held by 1 WorldCat member library worldwide

The feasibility of forming whiskers by vapor phase reaction was demonstrated. Whiskers of several materials were grown by oxidation (or reduction) and deposition from the vapor phase, including A1203, Si3N4, SiO2 and B. Principal effort was directed at producing whiskers A12O3 utilizing the reaction: 2A1C13(g) + 3CO2(g) + 3H2(g) reversibly yields A12O3(s) + 6CH1(g) + 3CO(g). Whiskers were grown on stationary substrates and gas-borne nuclei, although limited success was achieved with the latter. Whisker diameter appeared related to the grain size of the substrate or nuclei. High quality whiskers were produced by the process in terms of strength and length to diameter ratio. Measured mechanical properties compared very favorably with reported values obtained from whiskers formed by other processes. A special apparatus was developed for determining mechanical properties. The halide vapor reaction process appears amenable to high production rates because of the potential for continuous production techniques when compared to the batch production processes used presently. Purity and perfection are readily controllable. (Author)
Investigation of high temperature thermal expansion devices and design of a unit for use with thermal image heating( Book )

1 edition published in 1963 in English and held by 1 WorldCat member library worldwide

The double clamshell arc imaging system has been successfully applied in a practical arrangement for physical property measurements. Thermal ex pansion measurements of alumina and zircon have been made to 1950 K (1670 C). An inflection in slope of the thermal expansion of zircon was observed at 1570 K indicating a possible phase transition previously unreported. Simple modifications (coating of mirrors) will provide higher temperatures (calculated at 2260 K). Electrical property measurements can be made in the fieldfree environment. (Author)
 
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Languages
English (13)