Showing papers on "Chromium published in 1976"
TL;DR: In this paper, the chemical behavior of Cr(III) was studied in solutions, soil suspensions, and in soils of contrasting characteristics incubated at field capacity moisture, and it was shown that organic complexes formed at low pH and appeared to remain stable and soluble even when soil pH's were raised to levels where the Cr would be expected to precipitate.
Abstract: Chemical behavior of Cr(III) was studied in solutions, soil suspensions, and in soils of contrasting characteristics incubated at field capacity moisture. Sodium pyrophosphate, pH 4.8 NH₄OAc, and 0.1M NaF appeared to extract organically bound Cr(III), whereas 1M HCl removed inorganic Cr hydroxides and phosphates along with some organic Cr. Pyrophosphate and HCl extracts represented quantities of Cr(III) removed; NH₄OAc and NaF extracts appeared to characterize small readily removed fractions, that is, intensity factors. Soil organic complexes of Cr(III) formed at low pH and appeared to remain stable and soluble even when soil pH's were raised to levels where the Cr would be expected to precipitate. Adsorption and solubility behavior of Cr(III) as it varied with pH and treatments was similar to that of Al. Oxidation of Cr(III) to Cr(VI) was not demonstrated at all, under conditions of maximum aeration and high pH.
190 citations
Journal Article•
01 Jan 1976-Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
166 citations
TL;DR: In this article, the authors applied X-ray photoelectron spectroscopy to study the composition of the passive film formed on an extremely corrosion resistant amorphous Fe-10.%Cr-13at.%P-7at.
163 citations
TL;DR: A new sensitive, colorimetric method based on the direct measurement of light-absorption by an ion-exchange resin phase, which has sorbed the sample complex species, has been developed and determinations ofchromium(VI) with diphenylearbazide, iron(II) with 1,10-phenanthroline, copper with Zincon and cobalt with thiocyanate have more than ten times the sensitivity obtainable with conventional solution colorimetry.
154 citations
Journal Article•
01 Jan 1976-Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
TL;DR: In this article, the authors applied X-ray photoelectron spectroscopy to study the composition of the passive film formed on an extremely corrosion resistant amorphous Fe-10.%Cr-13at.%P-7at.
Abstract: X-ray photoelectron spectroscopy was applied to study the composition of the passive film formed on an extremely corrosion resistant amorphous Fe-10at.%Cr-13at.%P-7at.%C alloy in 1 N HCl. The passive film consists mainly of hydrated chromium oxyhydroxide which is a common major constituent of passive films on crystalline stainless steels. The extremely high corrosion resistance of the amorphous alloy can only in part be attributed to the formation of a protective hydrated chromium oxyhydroxide film.
154 citations
TL;DR: The corrosion resistance of amorphous iron alloys has been studied by total immersion tests and total immersion test as mentioned in this paper, and the results showed that they are resistant to mild corrosion.
Abstract: The corrosion resistance of amorphous iron alloys, whose practical application is expected because of their outstanding mechanical properties, has been studied by total immersion tests and...
139 citations
01 Jan 1976
TL;DR: In this article, the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C were investigated.
Abstract: Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.
123 citations
TL;DR: In this paper, the average moments at the iron and chromium sites and the disturbances in the individual moments arising from fluctuations in the near-neighbor environent were analyzed within the framework of the Marshall model.
Abstract: Diffuse neutron scattering measurements have been made on ferromagnetic iron-chromium alloys containing 15-, 30-, 50-, and 73-at.% Cr with the long-wavelength neutron spectrometer at Harwell. The results have been analyzed, within the framework of the Marshall model, to determine both the average moments at the iron and chromium sites and the disturbances in the individual moments arising from fluctuations in the near-neighbor environent. The average moment per iron atom rises to a small maximum around 15-at.% Cr and then decreases as the chromium concentration increases. The average chromium moment is negative and becomes smaller in magnitude as the chromium concentration increases. The sum of the disturbances at the iron and chromium sites changes sign as a function of concentration. The range of the disturbance appears to be smaller in chromium-rich than in iron-rich alloys.
110 citations
107 citations
TL;DR: In this paper, normal coordinate analyses of a series of chromium (III) dithiocarbamates are reported and the Ugo-Bonati distinguishing monodentate and bidentate bonding by the number of observed bands in the 1000 cm −1 region is shown to be valid, provided comparison is made between complexes containing the same alkyl group.
TL;DR: In this paper, the composition of leachates from some sanitary landfills in Norway and in the U.S.A. is described and attributed to the efficiencies of preventing water to enter the fills.
TL;DR: In this paper, the binding energy of Fe 2p 3 2 electrons from oxidized state shifted abruptly from ca.710·3 to ca. 709·6 eV and no more change in binding energy was observed at high chromium content.
TL;DR: Chromium toxicity decreased cation levels in plants as discussed by the authors and the highest level of Cr in leaves was about 30 ppm and in general there was a decreasing gradient in Cr from roots to stems to leaves.
Abstract: Chromium applied to a noncalcareous soil at 50 ppm did not decrease yields of bush beans (Phaseolus vulgaris L. var Improved Tendergreen), but when EDTA (ethylenediamine tetraacetic acid) was added with it, it did. Very little Cr was present in leaves. In solution culture 10-5
M Cr and higher were toxic. With solution culture the highest level of Cr in leaves was about 30 ppm and in general there was a decreasing gradient in Cr from roots to stems to leaves. EDTA had less effect in solution cultures on Cr toxicity because the Cr was already in solution. Chromium toxicity decreased cation levels in plants.
Patent•
27 Dec 1976
TL;DR: A class of amorphous metal alloys is provided in this paper in which the alloys are rich in iron, nickel, cobalt, chromium and/or manganese.
Abstract: A class of amorphous metal alloys is provided in which the alloys are rich in iron, nickel, cobalt, chromium and/or manganese. These alloys contain at least one element from each of three groups of elements and are low in metalloids compared to previously known liquid quenched amorphous alloys rich in iron, nickel, cobalt, chromium and/or manganese. The alloys can be readily formed in the amorphous state and are characterized by high hardness, high elastic limit and, for selected compositions, good corrosion resistance. Products made from these alloys include cutting tools, such as razor blades.
TL;DR: In this paper, the surface state of chromium in chromia-alumina catalysts calcined at 500 °C for 5 h was found to be predominantly Cr6+ at low chromia concentration catalysts.
Abstract: The XPS studies of chromia–alumina catalysts were carried out to elucidate the surface of these catalysts. Photoreduction was found to occur during the XPS measurements. Therefore, all spectra were measured rapidly to prevent any photoreduction. It was found that the information about the spin-orbit splitting of the Cr2P level is very useful for determining the valence state of chromium. The surface state of chromium in chromia–alumina catalysts calcined at 500 °C for 5 h is predominantly Cr6+ at low chromia concentration catalysts. However, the Cr3+ phase appears in catalysts of higher chromium content, and the surface concentration of Cr3+ increases with increasing content of supported chromia. The XPS spectra due to Cr5+ were observed after mild reduction of the catalysts. Moreover, it was found that almost all surface chromium is present as Cr5+ at low chromia content catalysts after mild reductions. Qualitatively, the results obtained by the XPS technique, which gives information about the surface of...
TL;DR: In this paper, low energy ion-scattering spectrometry has been used to obtain the composition depth profiles of air-formed oxide films on a series of iron-chromium alloys.
Abstract: Low energy ion‐scattering spectrometry has been used to obtain the composition‐depth profiles of air‐formed oxide films on a series of iron‐chromium alloys. By using iron, chromium, , , and as standards, the atom composition ratios Cr/Fe and have been obtained quantitatively as a function of sputtering time. The air/oxide interface appears to be oxygen‐rich or metal‐deficient. The Cr/Fe ratio is low at this interface but increases and peaks a few angstroms inside it. This ratio then diminishes continuously to its value in the alloy at the oxide/metal interface. The ratio diminishes continuously from the air/oxide to the oxide/metal interface and appears to be independent of alloy composition. There is no region of constant concentration of any of the components. The average Cr content of the oxide varies linearly with alloy composition but exceeds the Cr content of the alloy. This may be associated with the method of surface preparation. Based on differences in the shape of the composition profiles, it is speculated that the distribution and bonding of cations in the oxide phase, not their concentration, differentiate the stainless from the nonstainless alloys.
TL;DR: In this article, the maximum acceptable toxicant concentration (MATC) for brook and rainbow trout exposed to Cr(VI) in water with a hardness of 45 mg l−1 (as CaCO3) and a pH range of 7-8 lies between 0.003 and 0.006.
TL;DR: In this article, the early stages of oxidation of monocrystalline FeCr(100) and (110) between 700 and 900 K in the oxygen pressure range 10−9−10−6 Torr were observed.
TL;DR: In this paper, it is suggested that during the oxidation of stainless steels, matter is conserved at the oxide-metal interface by the creation of a dynamic balance between the chromium diffusion fluxes in the alloy and in the oxide.
Abstract: It is suggested that, during the oxidation of stainless steels, matter is conserved at the oxide-metal interface by the creation of a dynamic balance between the chromium diffusion fluxes in the alloy and in the oxide It is shown that the rate of oxidation is insensitive to alloy composition so that a necessary consequence is that the rate-controlling process is always diffusion through the oxide In addition, the interfacial concentration of chromium remains invariant with time at a value higher than that in thermodynamic equilibrium with the oxide Some of the predictions made with regard to the depth and kinetics of growth of chromium-depleted zones within the alloy have been checked experimentally inoxidation tests in CO2 at 1123° K on a 20Cr-25Ni stainless steel containing a dispersion of TiN particles It is concluded that the matter-conservation hypothesis is valid for this material
Patent•
30 Dec 1976TL;DR: A coating composition for producing high temperature, wear-resistant coatings on a metallic substrate, such as a nickel, cobalt, or iron base alloy, consisting of a cobalt base alloy with chromium, tantalum and carbon additions thereto, was proposed in this paper.
Abstract: A coating composition for producing high temperature, wear-resistant coatings on a metallic substrate, such as a nickel, cobalt, or iron base alloy, consisting of a cobalt base alloy with chromium, tantalum and carbon additions thereto. The basic composition may also contain one or more of aluminum, yttrium or the rare earth metals, silicon, manganese, or a dispersion of a metal oxide, such as alumina (Al 2 O 3 ).
TL;DR: In this article, the stability of binary mixtures of chemically dissimilar, monodispersed spherical particles has been investigated using the light scattering technique recently introduced by Lips and Willis (29).
Patent•
25 Feb 1976
TL;DR: A gas phase aluminizing process for alloys based on Group VI B and VIII metals such as chromium, iron, cobalt and nickel is disclosed in this paper, where it is particularly useful in the coating of internal passages of complex high temperature gas turbine hardware such as blades and vanes.
Abstract: A gas phase aluminizing process for alloys based on Group VI B and VIII metals such as chromium, iron, cobalt and nickel is disclosed. The process is particularly useful in the coating of internal passages of complex high temperature gas turbine hardware such as blades and vanes, where it has been found that the complex aluminum halide activators used herein have a "throwing power" greater than was heretofore obtained with the conventional halide activators such as ammonium chloride in the gas phase process.