Materials Literature
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Theoretical relationships and experimental data concerning thermal conductivity for a number of oxide materials have been compared over a wide temperature range. Deviations from the basic proportionality between k and 1/ T are caused by radiant‐energy transmission, a high Debye temperature, a low mean free path of the…
Se describen diferentes aparatos que permiten medir la consistencia de la pasta y del mortero de yeso. Se indican los resultados de algunos ensayos comparativos.
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En Clavarria, Argentina funciona un horno Lepol, por vía húmeda, con una producción diaria de 400 toneladas. El consumo de combustible es semejante al del proceso por vía seca.
La determinación de los sulfatos y de otros compuestos solubles mediante el percolador es sencilla y exacta. Por esta razón dicho método ha sido adoptado como proyecto de norma para la determinación da los componentes solubles perjudiciales.
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Se presenta un nuevo procedimiento para contrarrestar la acción nociva de las temperaturas bajas sobre los morteros y hormigones. Se Detallan su fundamento, ventajas e inconvenientes. El procedimiento es económico.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Temperature Dependence of Relaxation Mechanisms in Amorphous Polymers and Other Glass-forming LiquidsMalcolm L. Williams, Robert F. Landel, and John D. FerryCite this: J. Am. Chem. Soc. 1955, 77, 14, 3701–3707Publication Date (Print):July 1, 1955Publication History Publi…
Abstract Neutron-diffraction measurements demonstrate that the hydrogen atoms in the ferroelectric form of potassium dihydrogen phosphate are in ordered positions, in accordance with Slater’s theory and the polar orthorhombic structure. The maintenance of a crystal as a single ferroelectric domain by application of an…
thickness. The last equation is equivalent to the con- dition that the stress component cr"vanishes. Eliminat- ing all variables except ws in (5), we find d'we
The theoretical basis for exciting luminescence by the application of an electric potential to a crystalline dielectric or semiconductor is considered. Three mechanisms of excitation are each shown to be theoretically feasible in appropriate solids and with suitable local field conditions: (1) the ionization of impuri…
The orthogonalized plane wave (OPW) method is used to compute estimates of the energy eigenvalues associated with states for which k=0 in the valence and conduction bands of a perfect silicon crystal; these estimates are given in Table I. A simple method for determining an approximate crystal potential is described. T…
Abstract When subjected to high-energy radiation, polydimethyl siloxanes can be cross-linked to form insoluble amorphous structures which are transparent and have marked rubber-liko properties. Data are given on the relation between molecular weight and bulk viscosity, which is often used to characterize these polymer…
Abstract The electronic structure of a regular icosahedron of boron atoms is investigated theoretically by the method of molecular orbitals. It is found that thirteen bonding orbitals are available for holding the icosahedron together, besides the twelve outward-pointing equivalent orbitals of the separate atoms. The…
A Hopkinson bar wire strain gauge technique has been developed for the measurement of projectile penetration force as a function of time. The elastic strain wave resulting from projectile impact and penetration of the bar end is measured with oscillographic equipment; this strain pattern is a direct and continuous mea…
Abstract Experiments are described in which the effect of the presence of foreign substances on the rate of crystallization of natural rubber at −26° C is examined. It is shown that small amounts of suitable impurities, some of which are present in smoked sheet and other plantation rubbers, accelerate the crystallizat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeat Capacities at Low Temperatures and Entropies at 298.16°K. of Aluminates and Ferrites of Lithium and SodiumE. G. KingCite this: J. Am. Chem. Soc. 1955, 77, 12, 3189–3190Publication Date (Print):June 1, 1955Publication History Published online1 May 2002Published inissue 1…
Abstract Data are presented on the fracture of inoculated-iron thin-wall tubes, investigated under various ratios of axial to tangential stress, ranging from pure tension to pure compression. These data are consistent with published data on gray cast iron. It may be assumed that in cast-iron, plates of friable graphit…
In this paper the formation of a gelatinous hydrate phase from the natural dicalcium silicate minerals larnite and bredigite is described. Detailed study of the gel so formed indicates that the process of hydration is a solid reaction which is effeeted by diffusion. The preferred orientation of the hydrate phase sugge…