Showing papers on "Iron oxide published in 1985"

Magnetic behavior of free-iron and iron oxide clusters.

Abstract: We report the first measurement of the magnetic properties of isolated iron-atom clusters ranging in size from 2 to 17 atoms as well as the magnetic behavior of the monoxides and dioxides of (2-7)-atom iron clusters. Production of metal clusters is initiated by laser vaporization of an iron rod inside the throat of a high-pressure pulsed nozzle. The neutral metal cluster beam passes through a Stern-Gerlach magnet and the deflected beam is detected by spatially resolved time-of-flight photoionization mass spectrometry. From our analysis we conclude that the spin per atom of iron clusters is at least that of bulk iron, suggesting these small clusters are the precursors to bulk ferromagnetic iron.

Magnetic recording medium

Abstract: PURPOSE:To obtain a magnetic recording medium excellent in gloss and magnetic characteristics by providing a magnetic recording layer contg. a binder and a magnetic powder contg. iron carbide on a base material to constitute the magnetic recording medium. CONSTITUTION:The magnetic recording layer contg. the binder and the magnetic powder contg. iron carbide is provided on the base material. The binder consists of at least one of (a) copolymer of vinyl chloride, vinyl acetate and monomer having a polar group, (b) copolymer of vinyl chloride and monomer having a polar group, (c) polyvinyl acetal resin, (d) nitrocellulose and (e) polyurethane resin. The powder contg. iron carbide is obtained, for example, by allowing particles of iron oxyhydroxide or iron oxide to contact with a mixture of reductive gas containing no carbon. Thereby, excellent gloss and magnetic characteristics are obtained.

Boron Adsorption on Aluminum and Iron Oxide Minerals1

Abstract: Boron adsorption behavior was investigated on various crystalline and x-ray amorphous Al and Fe oxide minerals. Adsorption increased at low pH, exhibited a peak in the pH range 7 to 8, and decreased at high pH. The magnitude of B adsorption was much greater for the x-ray amorphous materials. Since B adsorbs specifically on Al and Fe oxide minerals, the constant capacitance model containing a ligand exchange mechanism was used to describe its adsorption behavior. The constant capacitance model was able to represent B adsorption on all minerals over the entire pH range studied (3-12) using the same set of surface complexation constants. With the exception of amorphous Al oxide, B adsorption on these oxide minerals could be successfully described by optimizing only the B surface complexation constant. Other nonexperimental parameters were held fixed at values identical to those previously used in modeling phosphate, silicate, and selenite adsorption on Al and Fe oxide minerals. Additional Index Words: anion adsorption, ligand exchange, surface chemistry, constant capacitance model. View complete article To view this complete article, insert Disc 4 then click button8

Redox equilibria and the structural states of ferric and ferrous iron in melts in the system CaO–MgO–Al2O3–SiO2–Fe–O;: relationships between redox equilibria, melt structure and liquidus phase equilibria

Abstract: Relationships between melt structure and redox equilibria of iron in CaO-AlrOr-SiOr-Fe-O and MgO-AlrOr-SiOr-Fe-O melts with CalAl and Mg/Al > 0.5 have been determined with M 0.5, and undergoes a gradual coordination transformation in the Fe3*pFe range between 0.5 add 0.3. In this Fe3+pFe-range, tetrahedrally- and octahedrally-coordinated ferric iron may coexist. The temperature-dependence of the Mcissbauer hyperfine parameters and the temperatureindependence of the intensity ofthe absorption envelope are consistent with a local structural unit that may be stoichiometrically similar to Fe.On. The Fe2+/Fe3+ is linearly correlated with polymerization (nonbridging oxygens per tetrahedrally coordinated cations, NBOru) and Al/(Al + Si) of the melt. There are linear relationships between log (Fe2*7Fe3+) and log fo, and between log (Fe2+/Fe3*) and 1/T (absolute temperature). The standard-state free energy of reduction of ferric to ferrous iron, calculated from these lines, decreases with increasing Zlrz (ionization potential) of the alkaline earth metal cation, with decreasing bulk melt NBO/T (more polymerized melts) and with decreasing AV(AI + Si) of the melt. In magnesium aluminosilicate melts with NBO/[:0.6 and AV(AI + Si):0.2 (typical values for quartz tholeiite and basaltic andesite) with 10 wt.% iron oxide added as FerO, the liquidus phase is tridymite when equilibrated with air. Calculations indicate that at fo" between 10-2 and 10-3 atm the liquidus phase changes to protoenstatite, and then to forsterite at even lower oxygen fugacities. Substitution of Ca (or Na) for Mg results in expansion of the metasilicate (pyroxene) liquidus field and contraction of that of tridymite. Fractional crystallization trends of magmatic liquids are, therefore, significantly dependent on oxygen fugacity, degree of polymerization of the magma (NBOA), Al/(Al + Si) and the relative abundance of alkali metals and alkaline earths.

Carboxylic/sulfonic/polyalkylene oxide polymer for use as scale, corrosion, and iron oxide deposit control

Abstract: The instant invention is directed to a process for inhibiting corrosion and the formation and deposition of scale and iron oxide in aqueous systems, comprising adding to the system at least 0.1 ppm of a water-soluble polymer having an intrinsic viscosity of 0.05 to 2.5 dl/g, prepared from: (a) 35 to 90%, by weight, of an unsaturated carboxylic acid, or its salt; (b) 5 to 40%, by weight of an unsaturated sulfonic acid, or its salt; and (c) 5 to 40%, by weight, of an unsaturated, polyalkylene oxide compound, the total of (a), (b) and (c) being 100% weight of the polymer.

A process for recovering valuable metals from an iron dust containing a higher content of zinc

Abstract: A process for recovering valuable metals from an iron dust with a high concentration of zinc comprising (1) pelletizing said dust into a pellet in a pelletizer, (2) preheating the resulting pellets by charging a hot gas to remove water, the loss on ignition and carbonaceous materials contained in the pellets, and in case of need, the conditions of gas charged are set up so as to reduce selectively iron oxide while controlling the reduction of zinc oxide practically at zero level, (3) melting and reducing zinc oxide, iron oxide and lead oxide in said pellets in an induction furnace to separate zinc and a part of lead by vaporization and iron and lead by means of the difference in their specific gravities, and collecting zinc and lead as crude ones, iron as molten pig iron and lead as crude one respectively.

Natural gas desulphurizing apparatus and method

Abstract: A desulphurization apparatus and method for natural gas in which red iron oxide is reacted with the sulphur compounds found in natural gas to remove these compounds from the gas. The treating solution is then recycled to regenerate the red iron oxide solution with elemental sulphur formed as a byproduct for removal.

Solid fuel and a process for its combustion

Abstract: A solid carbonaceous fuel containing up to 10% wt of calcium compounds and 0.1 to 5% wt of added iron added as oxide, carbonate or elemental iron or as as substantially halogen and sulphate-free iron-containing substances forming iron oxide or carbonate under furnace conditions. The additives act synergistically to reduce NOx.

Process for producing alkali metal ferrates utilizing hematite and magnetite

Abstract: Alkali metal iron (IV) and iron (VI) ferrates are produced by forming a particulate mixture of reactants including an alkali metal nitrogen oxygen compound and an iron material selected from the group of iron oxide, Fe2O3, Fe304 and an iron compound which self-reacts at a temperature less than about 1100°C to form Fe203. The mixture of reactants is subjected to a predetermined elevated temperature for a predetermined time duration sufficient to bring about a reaction between the reactants which produces at least one of iron (IV) and iron (VI) ferrates. The molar ratio of alkali metal nitrogen oxygen compound to the iron material is preferably in the range extending between about 4:1 and about 8:1.

Visible-light-induced photodissolution of α-Fe2O3 powder in the presence of chloride anions

Abstract: Haematite iron oxide (α-Fe2O3), an n-type semiconductor, has been shown to corrode in the presence of chloride anion in aqueous acidic media when in powder suspension. The rate of corrosion was enhanced by a factor of ten upon band-gap excitation using visible light. Surface adsorption and ease of complex formation with solution species are shown to be a major factor in the dissolution process. A mechanism for dissolution is proposed and implications for iron oxide powder photocatalysis are assessed.

Cored tubular electrode and method for the electric-arc cutting of metals

Abstract: A flux cored tubular metallic arc cutting electrode having a low carbon steel tube and a compacted core composition consisting of a particulate reactant metal such as magnesium, aluminum, zirconicum, titanium and alloys of at least two of the particulate reactant metals, mixed with an exothermically reactable metal oxide. Preferably the metal oxide is an iron group oxide such as iron oxide or nickel oxide. The particulate reactant metal is characterized by a free energy of formation of its oxide referred to 25° C. of at least 100,000 calories per gram atom of oxygen, the exothermically reactable metal oxide being characterized by a free energy of formation not exceeding 90,000 calories per gram atom of oxygen referred to 25° C. Additionally the electrode can contain an additive such as an arc stabilizer, a fluxing agent, a deoxidizer or a gas former.

Coal combustion to produce clean low-sulfur exhaust gas

Abstract: A process is provided for combusting sulfur-containing coal in a single step while producing an off-gas low in sulfur. The process comprises combusting finely divided coal in a furnace burner cavity in the presence of a finely divided iron oxide or iron powder and at least about 60% of the oxygen stoichiometrically required for substantially complete combustion of the coal to form a liquid iron oxysulfide phase and a turbulent atmosphere of combustion-product gases, liquid iron oxysulfide acting to scrub sulfur-containing gaseous species from the atmosphere to yield an essentially sulfur-free flue gas and a liquid iron oxysulfide slag containing substantially the sulfur originally contained in the coal.

An assessment of the system Fe-o-SiO2 using a structure based model for the liquid silicate

Abstract: The non-ideal activity of FeO(1) in iron silicate and iron oxide melts is described by treating the liquid as ideal and as consisting of a few complexes. The calculations show that the melt in the system Fe-O-SiO 2 can be described by considering the formation of the complexes Fe 3 Si 2 O 7 and Fe 3 Si 6 O 15 in addition to the components FeO, FeO 1.5 and Fe 2 SiO 4 . Using this model for the liquid phase, phase equilibrium relations including partial pressures of oxygen and activities of FeO(1) have been calculated in the system Fe-O-SiO 2 . The calculated results are consistent with available experimental and theoretical data.

Magnetically responsive reagent carrier and method of preparation

Abstract: A stable magnetically responsive, substantially remanence-free reagent carrier comprises an iron oxide colloidally dispersed in a smooth particulate polymeric matrix having preferentially a hydrated diameter of from about 0.5 to about 100 µm. The reagent carrier is prepared by a process which includes incorporating iron salts by passive transport into substantially spherical, water-swellable polymeric matrices, converting in situ the iron salts so-incorporated into their respective iron oxides. The carrier with a reagent attached thereto is useful inter alia in immunoassays.

Lamellar iron oxide pigments, a process for the production thereof and the use thereof

Abstract: In the production of an α-iron oxide pigment by the hydrothermal treatment of a trivalent iron-containing solution or suspension, the improvement which comprises adding to the solution or suspension prior to the hydrothermal treatment active α-iron oxide seeds with lamellar or disc-like crystal form and a specific surface of at least 10 m2 /g, whereby the resulting pigment is lamellar with an Fe2 O3 content of at least 88%, an average particle diameter of from 0.5 to 20 μm, an average ratio of diameter to thickness of from 20 to 100, and an almost normally distributed particle size distribution, the relative standard deviation of which, based on the average value of the normal distribution, is less than 0.3. The product has superior coloring properties and is used as a precursor compound for the production of lamellar magnetic pigments with superior magnetic properties.

Iron Oxide Properties Versus Strength of Ferruginous Crust and Iron-Glaebules in Soils

Abstract: We correlated the content, mineralogy and crystallinity of iron oxides with the strength of iron-rich materials in different environmental soil conditions. The strength, measured as penetration pressure of soft and hard materials from laterite as well as iron-glaebules and the surrounding matrix in Paleudult soils, showed a positive linear relationship with dithionite-extractable iron and a negative linear relationship with the proportion of oxalate to dithionite iron. We observed a predominance of goethite, hematite, or both in the hard materials and kaolinite in the soft material. The mean crystallite dimension (MCD) of goethite and hematite showed a positive linear relationship with the strength of the materials. The degree of Al substitution was found to be higher in the softer materials. Large crystals of goethite were observed by scanning electron microscopy in the harder materials. A suitable crystallization environment allowed the formation of large crystals, especially of the goethite type and in large amounts, that link together to form a rigid network and thereby cause the hardening of iron-rich materials.

Pigment consisting of a mixture of chromium oxide and iron oxide useful in high infra red reflectance gray vinyl composition

Abstract: This invention relates to a gray vinyl polymer material having improved tolerance to sunlight and other sources of infra red radiation. The vinyl polymer contains an inorganic pigment composed of chromium oxide (Cr 2 O 3 ) and iron oxide (Fe 2 O 3 ) wherein the weight ratio of the oxides is about 3:1. The pigment may be blended with titanium dioxide (TiO 2 ) to give a continuous spectrum of shades ranging from dark gray to light gray. The pigment is prepared by co-calcining the oxides of chromium and iron in finely divided form (-325 mesh) at a relatively low (900°-950° C.) temperature followed by grinding of the co-calcined product to 99% -325 mesh.

Process for producing acicular particles containing an iron carbide

Abstract: A process for producing acicular particles containing an iron carbide which comprises: (a) contacting or not contacting acicular iron oxyhydroxide or acicular iron oxide with a reducing agent which does not contain a carbon atom, and (b) contacting the iron compound of (a) with a reducing-and-carbonizing agent which contains one or more carbon atoms or a mixture thereof with a reducing agent which does not contain a carbon atom, provided that CO is excluded from the reducing-and-carbonizing agents of (b) when the contact in (a) is not carried out.

Process for the chemical thermodecomposition of higher halogenated hydrocarbons

Abstract: A halohydrocarbon is destroyed chemical-thermally by reacting at 600° to 800° C. with calcium oxide and/or calcium hydroxide. The process can be carried out problem-free by having the calcium oxide of hydroxide present in at least twice the stoichiometric excess based on the halogen to be bound and by having the composition contain 2-30 wt. % iron oxide.

Process for the preparation of bright, color-pure iron oxide red pigments

Abstract: A bright, color-pure iron oxide red pigment is produced by an improved process by precipitation of iron(II) salts in aqueous solution with an alkaline precipitating agent, oxidation at temperatures of from 20° C. to 100° C. and annealing of the resulting precipitation products under air to form iron oxide red pigments, wherein the improvement comprises before adding the alkaline precipitating agent, the iron(III) content of the aqueous solution is adjusted to 1 to 15 mol %, based on the total iron content of the iron salt solution.

Effect of heat treatment on reactively sputtered iron oxide thin films

Abstract: A pure Fe target was used to deposit iron oxide thin films by reactive rf sputtering. Both ‘‘regular’’ and ‘‘wet’’ H2 were used as reducing atmospheres to produce Fe3O4. Other parameters such as the nature of the substrate material, substrate table rotation during sputtering, and grain size were studied. The γ‐Fe2O3, formed by subsequent oxidation in air at elevated temperatures, can be formed over a wide range of oxidation temperatures using a prior ‘‘wet’’ H2‐reduced treatment. A slight increase in grain size was observed as a result of H2 reduction but no alteration of grain size occurred as a result of the subsequent oxidation anneal. Different magnetic properties and vacancy distribution in the spinel lattice were observed for γ‐Fe2O3 films deposited on silicon or glass substrates.