نتایج جستجو برای: chromium oxide
تعداد نتایج: 197927 فیلتر نتایج به سال:
T H E value of chromic oxide (chromium sesquioxide) as an indicator for estimating fecal output of sheep and cattle is dependent upon its concentration at a given sampling time providing the basis for estimating a standard recovery. However, chromic oxide excretion rate exhibits a diurnal variation (Hardison et al., 1959; Kane, Jacobson and Moore, 1952) which apparently precludes choosing a des...
I The continuous faecal marker chromic oxide, Cr,O,, and the intermittent marker brilliant blue were used together in metabolic balance studies of calcium and magnesium in two young women. 2. Faecal output was derived by four methods: no marker, brilliant blue, Cr,Os, or both brilliant blue and Cr,Os. 3. Balances of Ca and Mg derived by the four methods of obtaining faecal output were compared....
The very thin native oxide film on stainless steel, of the order of 2 nm, is known to be readily modified by immersion in aqueous media. In this paper, XPS and ToF-SIMS are employed to investigate the nature of the air-formed film and modification after water emmersion. The film is described in terms of oxide, hydroxide and water content. The preferential dissolution of iron is shown to occur o...
Chromium oxide nanoparticles were synthesized by the reduction of potassium dichromate solution with Mukia Maderaspatana plant extract. In electrochemical methods, Cr2O3 nanoparticles were synthesized by two ways, using platinum (Pt) electrodes and K2Cr2O7 solution with H2SO4 as medium in the first case. And chromium doped platinum electrode (Pt/Cr) in presence of NaHCO3 solution in second case...
Benzotriazole (BTA) and tolyltriazole (TTA) were used to passivate pure copper chromium bronze alloys for environmental protection. Using the chemical immersion treatment, a dense film of chromium-free passivation layer was formed on surfaces both alloys. Microstructure, crystalline phases bonds layers systematically characterized, mechanisms studied. The mainly consisted CuO, Cu2O, polymers Cu...
Condensation of 5-nitro, 3-chloro-, and 5-chlorosalicylic acid with formaldehyde afforded dimeric disalicylmethanes which were O-methylated with dimethyl sulfate and oxidized with chromium(VI) oxide to give the diarylketones 10, 11, 12. Wittig reaction with ylides obtained by deprotonation of alkyltriphenylphosphonium salts with sodium bis (trimethylsilyl)amide yielded a series of diarylalkenes...
Carbide coatings, due to their excellent anti-wear properties, are used to extend the life of molds exposed to abrasion forces. Various processes have been applied to produce carbide coatings. Thermo-reaction diffusion (TRD) using a molten salt bath could be considered as an economical method compared to other coating processes. In this study carbide-composite coatings using molten salt baths c...
We have used laser-initiated chemical vapor deposition to grow the chromium oxide thin films through the oxidation of Cr~CO!6 in an oxygen environment. While both Cr2O3 and CrO2 are present in the film, the relative weight of each phase depends on the oxygen partial pressure. The Curie temperature of the film increases and approaches the bulk TC of CrO2 ~397 K! as the partial oxygen pressure is...
This paper suggests an improved method for the sample preparation to quantify vanadium, chromium, nickel and copper in tool steel high-speed by using flame atomic absorption spectrometry. The suggested prepared two specimen solutions containing different internal standard elements: one included quantifications of vanadium or cobalt quantification chromium another phosphoric acid nickel, after w...
Chromium promotion of iron oxide based water-gas shift (WGS) catalysts prepared via co-precipitation/calcination was investigated. Mössbauer spectroscopy and XRD evidence that chromium is incorporated in the calcined hematite (?-Fe2O3) precursor irrespective doping level (0?12 wt.%). CO-TPR shows delays reduction active magnetite (Fe3O4) phase. WGS activity evaluated under realistic conditions ...
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