Cobalt content

The cobalt deposition rate on new, replacement, or decontaminated recirculation piping surface has been reduced by pretreating the piping using an atmosphere of oxygenated wet steam to form an oxide film (25). Studies have been conducted for both PWRs and BWRs to reduce the cobalt content of materials used in the nuclear parts of the plants, particularly in hardened and wear surfaces where cobalt-base alloys ( 50% Co) are used (26). Some low cobalt materials have been developed however, the use of the materials is limited to replacement parts or new plants. 

Hardness (qv), which determines the resistance of a material to abrasion and deformation, is affected not only by composition but also by porosity and microstmcture. Higher cobalt content and larger carbide grain size reduce hardness and abrasion resistance but iacrease the toughness of cemented carbides. The trade-off of abrasion resistance and toughness enables the cemented carbide manufacturer to tailor these materials to a wide variety of metal-cutting and nonmetal-cutting appHcations. 

The impetus for the synthesis of WC and subsequent development of cemented carbides came from the wire drawing industry where the hard metals are stUl used. The most commonly used grade is WC-6 wt % Co with medium grain size (1—2 p.m). Compositions having higher cobalt content are used in drawing tubes, rods, and bars. 

Eor water-based alkyd paints, greater (0.2% cobalt on a resin basis) concentrations of drier are required than for other systems because the reaction of the drier with water decreases the activity of the catalyst. The cobalt content of oil-based paint formulations is usually 0.01—0.05% cobalt. Although the concentration of cobalt in the formulations is small, the large volume of paints, inks, and varnishes constitute a significant use for cobalt chemicals. 

The cobalt content may be rapidly checked by titration with standard EDTA solution in the presence of xylenol orange as indicator (see Section 10.59). 

Superior water conditioners. These are tubular-shaped devices that employ permanent magnets (no electrical connection). The devices are designed with a cobalt-content alloy core, arranged so that water flows around the magnetic core and perpendicular to the magnetic fields. 

Decomposition rates of (Ni,Co) mellitates [1110] increase with increase in nickel content. The a—time curves for the pure components and the mixed mellitates were deceleratory throughout and there was no discontinuity in shape with changes in composition. Rates of decomposition of the solid solutions were appreciably greater than those expected from the decomposition of the individual components present (Fig. 19). The values of E determined for the initial stages of the decomposition of mixtures were close to that found for the nickel salt (184 kJ mole 1) and in the latter stages tended to increase towards that for cobalt mellitate (251 kJ mole-1). Values of A showed a systematic decrease with increase in cobalt content. 

Fig. 2.54. Cobalt contents of pyrite from the deposits of the Fujimi and Fudotaki groups of the Hitachi mine. Crossed, solid and hatched squares correspond to pyrite of ores involving large amounts of pyrrhotite, pyrite from sphalerite predominant ores, and pyrite from chalcopyrite predominant ores, respectively (Kase and Yamamoto, 1985).

Kase, K. and Horiuchi, Y. (1996) Cadmium, manganese, and cobalt contents of sphalerite from the Kieslager-type copper deposits, Japan. Resource Geology, 46, 137—150. 

Hassan et al [65] used a method for the determination of primaquine and other antimalarials, through ternary complex formation. The analytical aspects of the reaction between the widely used antimalarial drugs with cobalt and thiocyanate to form ternary complexes are described. Alternatively, determination of the cobalt content of the nitrobenzene extract using atomic absorption spectroscopy provided an indirect method for the determination of the drugs. Both methods are applied to the analysis of pharmaceutical preparation and the results obtained agreed well with those obtained with official methods. 

The parent NH4ZSM-5 (Zeolyst, Si A 1=15) was treated with a 0.1 M Co(N03)2 at room temperature. The ion exchange procedure was repeated three times and then the precipitate was washed with water and dried at 380 K. The cobalt content corresponded to Co/Al = 0.18. We used also MgZSM-5 (Mg/Al = 0.10) obtained by the treatment of NH4ZSM-5 with Mg(N03)2 solution. Propene (MERCK 99 %), as well as carbon monoxide, and nitrogen monoxide (Linde Gas Polska 99.95%, and 99.5% resp.) were used as adsorbates. 

The catalysts were characterized by inductively coupled plasma emission spectroscopy (ICP-ES Perkin Elmer Optima 3300RL) to determine cobalt content, x-ray diffraction (XRD Bruker A-500) with crystallite size determination using the Rietveld method, and temperature-programmed reduction (Zeton Altamira AMI-200) using 30 ml/min 10% H2/Ar and a ramp rate of 10°C/min. Surface area... 

The cobalt content of the catalyst was analyzed by ICP measurements (Perkin Elmer, Plasma 400) at the Institute of Chemical Engineering of the University of Erlangen-Nuremberg. 

The bulk sulfide Co9S8, dominant in catalysts with a high cobalt content,... 

A formerly unknown state, labeled Co-Mo-S in Fig. 9.19, which is most evident in sulfided Co-Mo catalysts of low cobalt content. 

The EXAFS data recorded after exposure to air of the unsupported Co-Mo catalysts with different cobalt content allow one to examine the effect of cobalt. In spite of a great uncertainty in the coordination numbers, the promoted catalysts seem to have a somewhat smaller domain size than the unpromoted catalyst as indicated both by the smaller second shell coordination numbers and by the larger effect of air exposure (i.e., reduced sulfur coordination number in first shell). This influence of cobalt on the domain size may be related to the possibility that cobalt atoms located at edges of M0S2 stabilize the domains towards growth in the basal plane direction. Recent results on C0-M0/AI2O3 catalysts indicate that Co may also have a similar stabilizing effect in supported catalysts (36). 

The spinel ferrites were fabricated by solid state reaction technique. Cobalt and Zinc ferrites CoxZnyFe204,(x=0.7,0.3,0.4,0.2 and y=0.3,0.7,0.6,0.8) were prepared by solid state reaction technique. The crystalline structure of the sample was investigated by X-ray diffraction(XRD). All samples show cubic spinel structure. The lattice parameter decreases with increasing cobalt content. Magnetic properties shows that the prepared sample exhibit ferromagnetic behaviour at room temperature. The saturation magnetization increases with increasing cobalt content. Curie temperature... 

Cobalt-based catalysts are effective in the ethanol reformation to hydrogen. Many oxides have been used to prepare supported cobalt catalysts of low cobalt content (circa 1 wt%) by impregnation from a solution of Co2(CO)8 catalysts were used in the ethanol reformation as prepared [156]. The performance of the catalysts in the steam reforming of ethanol was related with the presence, under reaction conditions, of metallic (ferromagnetic) cobalt particles and oxidized cobalt species. An easy exchange between small metallic cobalt particles and oxidized cobalt species was found. Comparison of Co/ZnO catalysts prepared from Co2(CO)8 or from nitrate precursor indicated that the catalyst prepared from the carbonyl precursor was highly stable and more selective for the production of CO-free hydrogen... 

The influence of benzylidene acetone on the electrodeposition mechanism of Zn-Co alloy was investigated [436]. A relationship between corrosion resistance, microstructure, and cobalt content in Zn-Co alloys was investigated [437] using X-ray photoelectron spectroscopy (XPS) and Auger spectroscopy [438]. The role of vitreous carbon, copper, and nickel substrates in Zn-Co deposition from chloride bath was analyzed [439]. 

Phase analysis and texture of the metal particles. Iron powders are constituted of the a-Fe phase with a body-centered cubic (bcc) lattice, whereas Fe-Co powders appear as a mixture of three phases that are quite similar to those of pure metals (bcc for a-Fe and a mixture of hep and fee for cobalt) (6). In the Fe.Nil(m system, a single fee phase is observed over the whole available composition range U s 25) with a linear dependence of the lattice parameter versus z, which shows the existence of a fee solid solution as already evidenced for the Co.rNiu)o-. system (33). The XRD patterns of the Fe [CovNi(1()o -,v)] i - powders depend on the composition An fee phase is always observed either as a single phase or as the main phase a second hep phase with weak and broad lines appears for a cobalt content x > 35 a third body-centered cubic (hcc) phase can be evidenced when x > 80. 

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