Materials Literature
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Conditions for carbothermal synthesis of α‐Si 3 N 4 are presented with special emphasis on the reaction temperature, C:SiO 2 ratio, and precursor mixing. With pure precursors, the conversion temperature is 1500° to 1550°C. An excess of C is necessary for complete conversion, and a simple sol–gelmixing technique provid…
The compound [Me3N(CH2)6NMe3]2[Mo8O26]·2H2O crystallizes from an aqueous solution of sodium molybdate and [Me3N(CH2)6NMe3]Cl2, slightly acidified with hydrochloric acid. The crystals are monoclinic, space group P21/n with a= 12.42(1), b= 12.897(3), c= 15.74(1)Å, β= 106.41(5)° and Z= 2. The structure was determined by…
High-resolution 27Al magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR)(78.15 MHz) spectra are reported for commercial and natural gibbsites and materials occurring in the thermal transformation sequences of gibbsite (boehmite; χ, α and ρ-aluminas; calcines produced at 400, 700, 900 and 1000 °C). S…
Abstract Amorphous celluloses were prepared by regeneration of cellulose from its solutions in the SO 2 –diethylamine–dimethylsulfoxide (SO 2 –DEA–DMSO) solvent system, and other selected SO 2 –amine–organic solvents. The celluloses were amorphous whether regenerated in water or in alcohols or other organic solvents;…
Fors soil (Tierp) is classified as an illitic, calcareous, frigid Udic Haploboroll according to the Soil Taxonomy and as a Calcaric Phaeozem in the FAO-system. It is a silty soil consisting of a thick dark brown coloured A-horizon and a subsoil rich in calcium carbonate and bases. Kungsängen soil (Uppsala) is classifi…
Translucent alumina ceramics with extremely high in-line optical transmittance to visible light and high mechanical strength were produced by applying HIP process to a sample which was densified at a relatively low temperature after injection molding. Measurements of bulk density and average grain size, X-ray diffract…
Porphyrin-α-diones can be prepared by photooxidation or SeO2-oxidation of β-hydroxyporphyrins, which are in turn readily synthesized from the corresponding copper(II) or nickel(II) 2-halo- and 2-sulphinyl-porphyrins by reaction with the anion of E-benzaldoxime; the efficient conversion of the porphyrinoquinoxaline 6 i…
The dehydrogenation and dehydration reactions of ethanol over TiO2, ZrO2 or HfO2 catalysts has been monitored in the gas phase and on the surfaces by infrared spectroscopy. The reaction pathways closely parallel those of methanol reported in the prevous paper (Part 2) with the addition of the direct dehydration reacti…
Impact and tensile properties of polypropylene filled with various minerals have been measured. The minerals investigated were dolomite, calcium carbonate, mica and wollastonite. The effect of particle shape, size, content and surface treatment on mechanical properties was studied. A special interest was devoted to th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and catalytic activity of alumina-supported platinum-cobalt bimetallic catalysts. 2. Chemisorption and catalytic reactionsLaszlo Guczi, Tamas Hoffer, Zoltan Zsoldos, Souad Zyade, Gilbert Maire, and Francois GarinCite this: J. Phys. Chem. 1991, 95, 2, 802–808Publica…
Investigations to determine the relevant electric and dielectric properties of certain insulating fluids which appeared most suitable from the viewpoint of environmental compatibility and inflammability are discussed. Two of these are silicone fluids based on linear polydimethyl siloxane (kinematic viscosity at 25 deg…
The effects of self-radiation damage due to alpha decay was studied as a function of cumulative decay events in synthetic zircon doped with 238Pu. The density of the Pu-doped zircon decreased exponentially with dose to a value corresponding to a density change of 14.2% at saturation. The initially crystalline material…
The thermal shock behavior of Si 3 N 4 has been determined with a new type of computer‐controlled testing equipment. Thin circular disks are heated up to 1350°C with two tungsten halogen lamps yielding heating rates up to 1000°C/s. The sample temperature is measured in situ with an infrared pyrometer and used to calcu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAntiplasticization effects on a secondary relaxation in plasticized glassy polycarbonatesK. L. Ngai, R. W. Rendell, A. F. Yee, and D. J. PlazekCite this: Macromolecules 1991, 24, 1, 61–67Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Pu…
Low temperature optical spectra of semiconductor microcrystals grown in a glass matrix demonstrate the effect of size quantization of the energy spectrum of Coulomb interacting electron-hole pairs. The phenomena and microscopic mechanism of ionization of microcrystals under optical excitation are regarded.
—When K. L. Mittal asked me to provide a historical account of the applications of silane coupling agents in adhesion, I decided to write in the form of a personal account of my last 45 years in this line of study. No attempt is made to make the history comprehensive, or to recognize the host of other researchers who…
X-ray photoelectron spectroscopy (ESCA), wettability measurements, and an ink adhesion test were used to characterize changes in the surface properties of air-corona-treated polypropylene (PP) films upon aging under a variety of storage conditions. No changes in ESCA O/C atomic ratios as a function of aging were obser…
The relation between deformation mode and β phase stability was investigated using Ti-16V and Ti-7Cr base alloys doped with Sn, Zr and Al as ternary or quaternary additions. Sn and Al additions change the dominant deformation mode from (332) twinning in the binary alloys to deformation induced martensitic transformati…
Functionally Gradient Materials (FGMs) characterized by the material having continuously varying material property from one surface to the other, have been prepared using gas, liquid or solid as starting material via several methods such as CVD, PVD, ion plating, plasma spraying, sintering or self-propagating high tem…
High-luminance green emission has been achieved from an electroluminescent (EL) device consisting of a Zn 2 SiO 4 :Mn thin-film phosphor and a thick BaTiO 3 ceramic insulator. The EL characteristics are strongly dependent on the preparation conditions of the Zn 2 SiO 4 :Mn thin film deposited by rf magnetron sputterin…