Materials Literature
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The high-temperature irradiation embrittlement of steels and nickel alloys is probably due to helium precipitation in grain boundaries. It would be desirable to retain the helium as fine bubbles evenly distributed within the grains. A fine dispersion in the metal matrix may act as nucleation site for helium bubbles an…
The X‐ray thermal expansion of TaC x was measured over the composition range from TaC 0.789 to TaC 0.997 at temperatures to 1000°C. The average thermal expansion coefficient, α, increased with increasing formula weight; α from 25° to 1000°C is 6.04, 6.37, and 6.96 × 10 −6 /°C for TaC 0.789 , TaC 0.912 , and TaC 0.997…
It is shown that a tracer plate will diffuse into a specimen which is being plastically deformed by a process called mechanical diffusion. The magnitude of the penetration via mechanical diffusion is about equal to the offset of the individual glide packets; this offset, in turn, is caused by the nonhomogeneous charac…
Summary Several studies (e.g. Bolt et al ., 1963; Beckett, 1964 a ) of the exchange equilibria between K and Ca on soil colloids or pure clay minerals have drawn attention to the presence of sites with different affinities for K. There is so far no evidence to indicate the location of sites with the highest affinity,…
Abstract The esterification of metal soaps, in the combination of zinc and calcium soaps, on poly(vinyl chloride) (PVC) has been carried out both in liquid and solid phase to determine why the reactivity of zinc soap decreases on addition of calcium soap, improving the long‐run heat stability of PVC and causing the we…
Abstract A theory is presented for a general treatment of the molecular size distribution, the gel point, and the post-gelation phenomena with respect to polymerization with formations of various kinds of interunit junctions, assuming (1) that all functional groups are equally reactive, and (2) that no kind of intramo…
Abstract Results of following the quantities of free Ca(OH) 2 and of tricalcium silicate (C 3 S) during the hydration of C 3 S, and also the influence of the presence of free CaO on this reaction are in accordance with the hypothesis of Stein & Stevels with regard to the hydration of C 3 S. at the first contact be…
Rigid urethane foams combine high strength-to-weight ratios with excellent electrical and thermal resistance-a combination of properties excellent for many applications. Unfortunately, the use of these foams has been limited partly because of a lack of information on rigid foam properties. This article is a summary of…
Phase transformation of VO 2 was studied by the optical microscopy, the X-ray difraction and the electrical resistance. Growth of transformed regions from sites of nucleation was observed in micrographs. The critical temperature of the transition and the rate of the growth were dependent on the mechanical strain. Appa…
A short review of the theories of crystal growth of perfect and imperfect planeS is given. Experimental evidence of two-dimensional nucleation mechanism of growth of perfect crystal planes is provided for the first time and some crystallographic parameters of this process are determined. A quantitative verification of…
Electron microscopy of natural and broken surfaces of echinoid skeletal plates reveals that the interior portions have the morphology of a single crystal, whereas the exterior is a polycrystalline aggregate with preferred orientation. These data help to resolve earlier contradictory x-ray and optical evidence.
Abstract The ring‐opening polymerizations of cyclooctene, cyclododecene, 1,5‐cyclooctadiene, 1,5,9‐cyclododecatriene, 3‐methylcyclooctene, and 3‐phenylcyclooctene have been carried out by using a two‐component catalyst system composed of ethylaluminum dichloride and tungsten hexachloride. NMR and infrared analyses of…
Detailed examination of a large number of copper water tanks and pipes showing pitting corrosion (taken from certaind is districts to which pitting is confined) revealed features that could not be reconciled with the conventiona1 explanation based on the presence of large cathodic areas surrounding small anodic corros…
Measurements of changes in permittivity, tanδ, and d∂∂ as function of compressive stress parallel to the polar axis are presented for lead zirconate—lead titanate transducer ceramics. The “hard” ceramics (PZT-4 and PZT-8) suitable for high-power application show large changes of properties for stresses to 20 kpsi, but…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMoessbauer spectra of some porphyrin complexes with pyridine, piperidine, and imidazoleLawrence M. Epstein, Darel K. Straub, and C. MaricondiCite this: Inorg. Chem. 1967, 6, 9, 1720–1724Publication Date (Print):September 1, 1967Publication History Published online1 May 2002P…
The results of an investigation of the structure of Ni+ +, ions in Na2O–B2O3 glasses by optical and EPR techniques are reported. The coordination about the ion sites is found to be octahedral, and a small amount of covalency is inferred. The crystal-field splitting of the d8 levels decreases as the Na2O content of the…
Abstract Graphitoxid entsteht aus Graphit und leicht Sauerstoff abgebenden Oxydationsmitteln nur dann, wenn der Graphit zuerst zum Graphitsalz (C A − · 2 HA) oxydiert wird. Die weitere Oxydation verläuft um so schneller und vollständiger, je mehr Wasser die Oxydations‐mischung enthält, wobei jedoch eine kritische Konz…
Abstract A simple theory is developed which correlates the Izod impact strength of polymers with ( G ′ 100 ‐ G ′ 300 ) 2 / G ′ 100 , where G ′ 100 and G ′ 300 are dynamic shear moduli at 100°K. and 300°K., respectively. The theory assumes the Maxwell element for the material and the fracture time smaller than the rela…
A modified superposition principle has been employed to describe creep in the nonlinear range under combined stresses which change abruptly from time to time. The stress function fij employed is derived from three integrals of the multi-integral theory for constant stress. Several means of treating the nonlinearity in…
The electrostriction and polarization in the perovskite-type ferroelectric ceramics have been calculated in the state under the arbitrary biasing field. Domain configurations produced by 180°-reversal or 90°-rotation have been represented here by the threshold angle θ 180 or θ 90 ; that is, domains, making smaller ang…