Materials Literature
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Abstract Numerous failures of aluminium–brass heat‐exchanger tubes and copper–nickel–iron sea‐water pipes in polluted estuarine sea‐water were found to be associated with sulphide films which stimulated pitting and stress‐corrosion cracking at holidays (breaks) in the film. The use of sodium dimethyl dithiocarbamate w…
Abstract The swelling of natural rubber vulcanizates under equal two‐dimensional compression has been investigated. The degree of crosslinking of the vulcanizate and the nature of the swelling liquid have both been varied. The reduction in equilibrium swelling produced by the stresses is found to agree well with theor…
The prediction that metal rich diboride compounds would exhibit superior oxidation resistance was verified. Studies were made of high pressure hot pressed Hf and Zr diborides, the most oxidation resistant diborides, at B/ metal ratios between 1.7 and 2.1. Measurements between 1200 and 2200 K at partial pressures of 7…
Based upon the recent observations that a slip dislocation in b.c.c. metals is associated with three twinning dislocations (Ogawa and Maddin 1964), the atomic configuration of the dissociated slip dislocation as well as those of mono-layer, two-layer and three-layer twins were studied in detail. The interfacial energi…
α-Zn 3 (PO 4 ) 2 crystallized in the monoclinic space group C2/c with lattice parameters a = 8.14 ± 0.02 Å, b = 5.63 ± 0.01 Å, c = 15.04 ± 0.04 Å, β = 105°08′ ± 05′, and Z = 4. The cations are found in two types of tetrahedrally coordinated sites. One-third of the cations lie on twofold axes within an oxygen tetrahedr…
A typical coated diamond has been examined by x-ray diffraction and absorption topography. At the commencement of the coat an abrupt change to fibrous, radial growth occurs. This radial mode of growth gives rise to the general spherical habit of thickly coated diamonds. In the specimen studied the range of misorientat…
Abstract The thermal conductivities of linear high polymers were studied experimentally and theoretically. A theory of thermal conductivity in linear amorphous high polymers was derived based on a simple model of molecular structure. Predictions on the effects of molecular weight and molecular orientation on thermal c…
Constitution of iron-germanium system is discussed based on x-ray and magnetic studies, and a new phase diagram is proposed. Fe solid solution (α) ranges up to 20.4 at.% Ge at 710°C and to 21.3 at.% Ge at 520°C. Homogeneity range of the most iron rich compound ( ε above 700°C and ε 1 below) are 23.8–26 at.% Ge at 710°…
Abstract It has recently been postulated that viscous flow, or plastic deformation, occurs near the tip of an advancing crack in glassy amorphous polymers such as Plexiglas, and this results in molecular orientation at the fracture surface. The evidence for this has been the appearance of colors on fresh fracture surf…
By use of electron microbeam probe analysis on quenched samples, the concentration distribution of CaO, A1 2 O 3 , and SiO 2 was determined across the boundary layer between molten calcium aluminum silicates and dissolving or growing sapphire and fused silica. A definite shift in the concentration ratios of the solven…
Co${\mathrm{F}}_{2}$ is a simple two-sublattice antiferromagnet and has a rutile crystal structure. Each ${\mathrm{Co}}^{++}$ ion is surrounded by a rhombically distorted octahedron of fluorine anions and the crystal-field parameters are known from an analysis of infrared absorption measurements. A good description of…
A polarization technique for the measurement of electronic and ionic transference numbers in mixed conductors is described; also a discussion of the conditions governing its applicability. The application of this technique is demonstrated by measurements on the solid solution Zr0.85 Ca0.15 O1.85, which is shown to be…
Accurate values of the parallel and perpendicular components of g-factor and hyperfine coupling tensor were determined for [CrOCln]—(n−3) where n=4 and 5, by the ESR line shape analysis. It was shown by a molecular orbital treatment that these magnetic parameters can be explained consistently by taking into account of…
The crystal structures at 298°K of MnCl2·2H2O and FeCl2·2H2O have been refined by means of three-dimensional differential syntheses using diffractometer single-crystal x-ray-intensity data. The crystal structures of these isomorphic compounds consist of polymeric chains of metal and chlorine ions arranged in a near-sq…
Abstract The viscoelastic properties and thermal expansion properties of bisphenol A polycarbonate have been studied in the neighborhood of the major glass transition temperature. A discussion is given of the possible relation of these properties to the unusual impact resistance of this polymer in the glassy state.
Population of luminescent levels of rare-earth ions in solution has been accomplished through energy transfer from excited, nonchelated organic molecules. Twenty-one aromatic aldehydes and ketones have been shown to be capable of transferring energy to Tb3+ or to Eu3+. It is suggested that a diffusion-controlled proce…
A scanning electron microscope using three magnetic electron lenses and a thermionic electron source has been developed to give an electron probe size of 50 Å and a resolution in reflection of 100 Å. This experimental result agrees with the theoretical limit on electron probe size and current found by consideration of…
The interaction between two neighboring localized magnetic moments in the transition metals and alloys in studied by using the Anderson model generalized to the case of five-fold degenerate d-orbitals. The effective exchange energy and the change of the localized moments due to the d-d covalent admixture are calculate…
Abstract The linear thermal expansion of molded PTFE samples of various crystallinities was measured in the vicinity of the transition at about 400°K. In the plot of length of the specimen versus temperature, an inflection of the straight line was observed in the temperature range from 388 to 402°K., the mean value be…
Abstract Heats and entropies of fusion of polymers are customarily evaluated through melting point depression measurements with the assumption that the observed and thermodynamic melting points are nearly identical. However, it has recently become evident that the crystal surface free energy is not negligible, so that…