Manual of cement testing
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Materials Literature
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The top-fired tunnel kiln
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Measuring volume shrinkage of resinous mortars
Este método, que mide la retracción total de morteros de resinas al pasar de la forma plástica al estado completamente curado, puede ser útil para predecir la retracción máxima de dichos morteros.
Electrical curing of concrete
Se indican las normas prácticas que se han de seguir al llevar a cabo el curado eléctrico del hormigón.
Der schachtofen von morgen
Se ha conseguido que la cocción con carbón pulverizado sea económica gracias a un nuevo modelo de parrilla. Un nuevo procedimiento de cocción con granulación y recubrimiento de los gránulos mediante una capa exenta de carbón, permite reducir considerablemente las pérdidas de CO del horno vertical.
La qualité des argiles à terre cuite et leur composition granulométrique
Se destaca, tomando como base numerosas determinaciones, la importancia, en el plan industrial, de la estructura granulométrica de las arcillas, como factor principal que determina la actitud de una arcilla para preparar un determinado producto.
Hysteresis Loops of Mixtures of Ferromagnetic Micropowders
A treatment is given of the hysteresis loops of dilute mixtures of various sizes of ferromagnetic particles. Three ranges of particle size are considered: very small particles called ``super-paramagnetic'' which are single domain and equilibrate resulting from thermal vibrations, single domain particles which are larg…
Properties of piezoelectric ceramics in the solid-solution series lead titanate-lead zirconate-lead oxide: Tin oxide and lead titanate-lead hafnate
Co mpositional proximity to a morphotropic t ransformation between two ferroelectric solid-s olution phases seems to yie ld ceramic transducers having desirable properties over a wide range of te mperature. Examples of t his phenomenon were observed in the systems PbTi03-PbZr03, PbTi03-PbO:Sn02, PbTi03-PbZr03-PbO:SnO"…
The effect of particle interaction on the coercive force of ferromagnetic micropowders
Abstract Previous theoretical work by Stoner & Wohlfarth (1948) on the magnetic properties of single domain ferromagnetic particles is extended to take some account of the interaction between the particles. Earlier theoretical considerations of the interaction problem are critically discussed (§2), and the experim…
The release of energy during annealing of deformed metals
Abstract The method described previously for measuring the energy stored in cold-worked metals has now been applied to nickel and arsenical copper as well as to pure copper. Torsion, tension and compression have been used as methods of deformation, and the heating rates were 2, 4 and 6° C/min. For all these materials,…
Theory of the Magnetic Susceptibility of Graphite
The theory of the magnetic susceptibility of graphite is presented in terms of a three-dimensional Wallace electron energy band structure. The experimentally observed variation with temperature is explained in a satisfactory manner, provided the interplane resonance integral occurring in the band approximation is give…
Superconductivity of Zirconium Alloys
The superconducting transition temperatures of alloys between zirconium and VIIIth column elements are substantially higher than those of zirconium. The same is true for zirconium-gold alloys. This observation confirms a rule previously established about the height of transition temperatures.
Magnetic Moment Arrangements and Magnetocrystalline Deformations in Antiferromagnetic Compounds
The neutron diffraction data of Shull et al. on the powder specimens of MnO, FeO, CoO, etc., are re-examined. It is found that except for FeO the observed Debye-Scherrer patterns may be produced by a number of magnetic moment arrangements with the same antiparallel coupling among the moments on the next nearest neighb…
Criterion for the Occurrence of Luminescence
A mechanism is suggested for the nonradiative quenching of excited states of simple impurity centers, namely a crossover to the ground electronic state of the center immediately after excitation and before thermal equilibrium has had time to come about. It is proposed that this mechanism is responsible for the absence…
Symmetry Properties of the Energy Bands of the Zinc Blende Structure
The symmetry properties of the one-electron energy bands of a crystal of the zinc blende structure are studied by means of group theory. This is done both with and without the inclusion of spin-orbit coupling. The character tables and compatability tables are obtained for the various irreducible representations of the…
Lattice Constants of Graphite at Low Temperatures
The lattice constants of a graphite single crystal, natural graphite powder, and artificial graphite powder have been measured at 297\ifmmode^\circ\else\textdegree\fi{}K, 78\ifmmode^\circ\else\textdegree\fi{}K, and 4.2\ifmmode^\circ\else\textdegree\fi{}K. The $a$-spacing does not change in this temperature range withi…
Neutron Diffraction Study of the Magnetic Properties of the Series of Perovskite-Type Compounds[(1−x)La, xCa]MnO3
A study has been made of the magnetic properties of the series of perovskite-type compounds $[(1\ensuremath{-}x)\mathrm{La}, x\mathrm{Ca}]\mathrm{Mn}{\mathrm{O}}_{3}$. The investigations have been made primarily by neutron diffraction methods, but x-ray diffraction measurements of lattice distortions and ferromagnetic…
Considerations on Double Exchange
Zener has suggested a type of interaction between the spins of magnetic ions which he named "double exchange." This occurs indirectly by means of spin coupling to mobile electrons which travel from one ion to the next. We have calculated this interaction for a pair of ions with general spin $S$ and with general transf…
Theory of the Role of Covalence in the Perovskite-Type Manganites[La, M(II)]MnO3
The theory of semicovalent exchange is reviewed and applied to the perovskite-type manganites $[\mathrm{La}, M(\mathrm{II})]\mathrm{Mn}{\mathrm{O}}_{3}$. With the hypothesis of covalent and semicovalent bonding between the oxygen and manganese ions plus the mechanism of double exchange, detailed qualitative prediction…
Radiation induced changes in the structure of poly iso butylene
Abstract Polyisobutylene suffers random main-chain fracture when exposed to high radiation. Identical results are produced by electron and γ-radiation and the average energy absorbed per break amounts to 20 eV at 20° C. The unsaturation produced is proportional to the number of breaks. A new absorption band appears in…