Thermal conductivity of rock-forming minerals
Rock forming monomineralic aggregates thermal conductivity at ordinary temperature and pressure in relation to density, crystal structure and chemical composition
Horai, K.↗
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Results for “Crystal structures”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Growth of In2Bi whiskers
In-Bi whisker growth by squeeze technique, measuring crystal structure by X ray analysis and melting point method
Davis, J. H.↗
Single crystal X-ray investigation of deformation in terrestrial and lunar ilmenite
Single crystal structure of shocked terrestrial and lunar ilmenite from X ray precession and Laue analyses
Chao, E. C. T.↗
Proposed semiconductor film improvement
Film grown in inert carriers (A, He, or N) displays low impurity, high mobility, and improved crystal structure. Annealing steps used in growing process improves film quality and allows utilization of film for Gunn and LSA devices.
Manasevit, H. M.↗
A fundamental review of the friction and wear behavior of ceramics
The basic concepts associated with the friction and wear of materials are discussed as they relate to ceramics. Properties of ceramics such as crystal structure, crystallographic orientation, mechanical deformation, and surface chemistry are reviewed as they influence friction and wear. Both adhesive and abrasive wear of ceramics are discussed. The friction and wear of ceramics are examined in contact with themselves and when in contact with metals. The influences of environmental constituents such as water and hydrocarbons on friction and wear are reviewed. Materials discussed, by way of example, include aluminum oxide, rutile, calcium fluoride, and lithium fluoride.
Buckley, D. H.↗
Oxidation state of iron in plagioclase from lunar basalts.
Determination of the oxidation state of iron in the plagioclase from the coarse-grained basalts 10044 and 12021, using Mossbauer spectroscopy. The location of iron in the crystal structure was also investigated. The spectra show that iron is in the high-spin ferrous state, and they located at least two distinct positions with different coordination numbers. Some excess resonant absorption is probably due to Fe(3+), although the Fe(3+) doublet could not be positively resolved.
Hafner, S. S.↗
Effects of ultraviolet radiation on lattice imperfections in pyrolytic boron nitride.
Pyrolitic boron nitride was exposed to 310 equivalent sun hours of ultraviolet radiation in a space environment simulator with the objective to evaluate its applicability as a pigment for a thermal control coating and to identify radiation damage using X-ray diffraction techniques. Lattice parameter comparisons show a definite increase in lattice imperfections in the crystal structure resulting from the ultraviolet irradiation. This sensitivity to radiation damage makes pyrolitic boron nitride unsuitable as a pigment for thermal control coating.
Buckley, J. D.↗
Measurements on A-15 films.
Description of a method for the preparation of A-15 superconducting films by cosputtering. This method is useful for the study of both alloying effects and crystal structure stability determinations. Measurements in the A-15 systems Nb3Al, Nb3Al sub .75 Ge sub .25, and V3Si prepared by this method are presented. In addition a new method for the preparation of V3Si by 'reactive diffusion' is presented.
Cadieu, F. J.↗
A fundamental review of the friction and wear behavior of ceramics.
The basic concepts associated with the friction and wear of materials are discussed as they relate to ceramics. Properties of ceramics such as crystal structure, crystallographic orientation, mechanical deformation and surface chemistry are reviewed as they influence friction and wear. Both adhesive and abrasive wear of ceramics are discussed. The friction and wear of ceramics are examined in contact with themselves and when in contact with metals. The influences of environmental constituents such as water and hydrocarbons on friction and wear are reviewed. Materials discussed, by way of example, include aluminum oxide, rutile, calcium fluoride, and lithium fluoride.
Buckley, D. H.↗
The liquid crystal light valve, an optical-to-optical interface device
A photoactivated liquid crystal light valve is described as an optical-to-optical interface device (OTTO) which is designed to transfer an optical image from a noncoherent light beam to a spatially coherent beam of light, in real time. Schematics of OTTO in use, the liquid cyrstal cell, and the liquid crystal structure are presented. Sensitivity characteristics and the principles of operation are discussed.
Jacobson, A. D.↗
Development of ductile high-strength chromium alloys, phase 2
Strength and ductility were evaluated for chromium alloys dispersion hardened with the putative TaC, TaB, CbC, and CbB compounds. TaC and TaB proved to be the most potent strengtheners, but when combined, their effect far outweighed that produced individually. Tests at 1422 K (2100 F) on an alloy containing these two compounds at the combined level of 0.5 m/o revealed a 495 MN/sq m (70 ksi) tensile strength for wrought material, and a 100 hour rupture strength of 208 MN/sq m (30 ksi) when solution annealed and aged to maximize creep resistance. These levels of high temperature strength greatly exceed that reported for any other chromium-base alloy. The ductile-to-brittle transition temperature (DBTT) of the two phase strengthened alloy occurred at approximately 588 K (600 F) when heat treated to optimize creep strength and was not improved by fabrication to produce a wrought and recovered microstructure. The lowest DBTT measured on any of the alloys investigated was 422 K (300 F). Strengthening phases actually formed in Cr-Ta-B and Cr-Cb-B compositions are probable M2CrB2 (M=Ta or Cb) compounds of tetragonal crystal structure. The likely habit relationship between these compounds and chromium is postulated. Cube habit coherency was identified for TaC precipitation in chromium by electron microscopy. In another study, the maximum solubility of carbon in chromium was indicated to lie between 3/4 and 1 a/o and that of boron to be 1/2 a/o.
Filippi, A. M.↗
Effect of Various Material Properties on the Adhesive Stage of Fretting
Various properties of metals and alloys were studied with respect to their effect on the initial stage of the fretting process, namely adhesion. Crystallographic orientation, crystal structure, interfacial binding energies of dissimiliar metal, segregation of alloy constituents and the nature and structure of surface films were found to influence adhesion. High atomic density, low surface energy grain orientations exhibited lower adhesion than other orientations. Knowledge of interfacial surface binding energies assists in predicting adhesive transfer and wear. Selective surface segregation of alloy constituents accomplishes both a reduction in adhesion and improved surface oxidation characteristics. Equivalent surface coverages of various adsorbed species indicate that some are markedly more effective in inhibiting adhesion than others.
Buckley, D. H.↗
Diffusion bonding and its application to manufacturing
In its simplest form diffusion bonding is accomplished by placing clean metal surfaces together under a sufficient load and heating. The natural interatomic attractive force between atoms transforms the interface into a natural grain boundary. Therefore, in principle, the properties of the bond area are identical to those of the parent metal. Other advantages of diffusion bonding over conventional methods of bonding include freedom from residual stresses, excessive deformation, foreign metals, or changed crystal structures. Stainless steels, nickel-base superalloys, and aluminum alloys have all been successfully joined. Complex hardware, including integrated flueric devices, jet engine servovalves, and porous woven structures have been fabricated. The processing involved is discussed, along with such theoretical considerations as the role of metal surfaces, the formation of metal contact junctions, and the mechanisms of material transport in diffusion bonding.
Spurgeon, W. M.↗
Chemical-ionization visible and ultraviolet gas lasers: A concept
Charge-transfer reactions or Penning ionization reactions are used to produce population inversions between electronic states of molecular ions which should result in stimulated emission in ultraviolet and visible regions. Such lasers could be used in study of short-lived reaction intermediates, crystal structure and scattering, and photolysis.
Laudenslager, J. B.↗
Effect of various material properties on the adhesive stage of fretting
Various properties of metals and alloys have been studied with respect to their effect on the initial stage of the fretting process, namely adhesion. Crystallographic orientation, crystal structure, interfacial binding energies of dissimiliar metal, segregation of alloy constituents and the nature and structure of surface films have all been found to influence adhesion. High atomic density, low surface energy grain orientations exhibit lower adhesion than other orientations. Hexagonal metals in general manifest less adhesive wear than cubic metal. Knowledge of interfacial surface binding energies can assist in predicting adhesive transfer and wear. Selective surface segregation of alloy constituents can accomplish both a reduction in adhesion and improved surface oxidation characteristics. Equivalent surface coverages of various adsorbed species indicate that some are markedly more effective in inhibiting adhesion than others.
Buckley, D. H.↗
Materials research at Stanford University
Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.
Source record↗
Fretting in aircraft turbine engines
Fretting usually produces both polished and pitted areas. Fretting occurs in connection with the relative motion between contacting surface elements. Particular attention is given to fretting in seals, splines, fans, compressors, and turbine blades. Recommended approaches to mitigate fretting problems include a reduction of the adhesion between two surfaces. Approaches for doing this may include the development of alloys which spontaneously generate a self-healing surface film, different in composition from the bulk alloy. Other fundamental adhesion studies have shown that surface crystal structure and crystallographic orientation significantly affect the adhesion properties of alloys.
Johnson, R. L.↗
Effect of various material properties on the adhesive stage of fretting
Various properties of metals and alloys have been studied with respect to their effect on the initial stage of the fretting process, namely adhesion. Crystallographic orientation, crystal structure, interfacial binding energies of dissimiliar metal, segregation of alloy constituents and the nature and structure of surface films have all been found to influence adhesion. High atomic density, low surface energy grain orientations exhibit lower adhesion than other orientations. Hexagonal metals in general manifest less adhesive wear than cubic metal. Knowledge of interfacial surface binding energies can assist in predicting adhesive transfer and wear. Selective surface segregation of alloy constituents can accomplish both a reduction in adhesion and improved surface oxidation characteristics. Equivalent surface coverages of various adsorbed species indicate that some are markedly more effective in inhibiting adhesion than others.
Buckley, D. H.↗