Cobalt deposits

J. C. Wiltshire, "Seafloor Cobalt Deposits A Major Untapped Resource," presented at Cohalt at the Crossroads, Intertech Conferences, Herndon, Va., June 1992. 

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. 

Plating solutions used in nickel electroforming are primarily the Watts bath and the nickel sulfamate bath. Watts baths exhibit higher stress and require additives for stress control, which may affect other properties. Sulfamate baths produce much lower stress and are preferred where purer nickel or nickel—cobalt deposits ate needed. ASTM specifications are available that describe the mandrels and plating solutions (116,162). 

The presence of a site with a low metal-metal coordination is compatible with the non-crystalline nature of the cobalt deposits [64]. It is to be expected that these sites exhibit different chemical reactivity than the usual adsorption sites. This can be verified by subsequent deposition of a small amount (0.1 A) of Pd atoms, which are known to nucleate exclusively on the cobalt particles [64]. The corresponding IR spectrum is shown as the bottom trace in Fig. 6. It is seen that an additional peak appears at 2105 cm which is readily assigned to CO bound terminally to Pd. More importantly, the growth of this Pd feature is completely at the expense of the carbonyl species, indicating that Pd nucleates almost exclusively at these low coordinated sites and prevents the formation of the carbonyl species. 

Teter et al. filed a series of patents aimed at the production of organic compounds containing nitrogerf or the production of nitriles and amines from ammonia and olefins by passing mixtures of olefin and NH3 over transition metals, mainly cobalt deposited on various supports at 250-370°C and 100-200 bar [27- 3]. With cobalt on asbestos, a mixture of amine, nitrile, olefin hydrogenation product, polymers, and cracking products is obtained (Eq. 4.1) [31]. 

We report here results related to the catalytic behaviour of dodecacarbonyl-tri-iron and tri-ruthenium, bis(cyclopentadienyl-dicarbonyliron) and octacarbonyl-di-cobalt deposited on Y-zeolites under F-T conditions. The influence of the nature of the zeolite and of the metal, the dispersion of the metal and the reaction conditions upon activity and products distribution were investigated. 

Holmen and coworkers15-17 also observed a loss in activity when water was introduced to un-promoted and Re-promoted cobalt deposited on >-Al203. In a recent paper similar results were reported for Co Re supported on both narrow-pore and wide-pore y-Al203,18 and permanent deactivation was observed when the inlet ratio H20 H2 was 0.7. The same group reported that the rhenium-promoted catalysts lost activity more rapidly than their un-promoted counterparts.14-1619... 

Kim43,49 utilized the effect of water on the activity in FTS patents using un-promoted and promoted cobalt deposited on Ti02 (rutile). For a wide range of external H20 addition levels, beneficial effects of increased productivity could be realised. However, when more than 28% water was added to the feed of the rhenium based version, the CO conversion was affected negatively. More recent experimental investigations of the effect of added water on the rate of the FTS over titania-supported Co are summarized in Table 4. 

Figure 8.14. Rate of electroless cobalt deposition as a function of pH at 30 and 100 g/L citrate one-factor experiments. (From Ref. 65, with permission from the Electrochemical Society.)...

Fig. 5 X-ray photoelectron spectra of the Co lp p) core levels before and after a 2, 4, 6, 12, and 24 A thick cobalt deposition on Alq3. The inset shows the XAS and XMCD spectra recorded at 300 K for a 20-A deposition of cobalt on Alq3. Taken from [35] with permission...

Xu W, Brauer J, Szulczewski G, Driver MS, Caraso AN (2009) Electronic, magnetic, and physical structure of cobalt deposited on aluminum tris(8-hydroxy qunioline). Appl Phys Lett 94 233302... 

The influence of convection, pH, and Zn(II) of solution on electrodeposition on GC electrode of zinc-cobalt alloys was studied by Gomez and Valles [229]. The presence of zinc in the bath always decreases the rate of the cobalt deposition. 

A hydroxide suppression model first proposed by Dahms and Croll (2) explains anomalous codeposition behavior of zinc-iron group alloys. This explanation was later supported by a number of workers (3) who measured a rise in pH near the cathode surface during the deposition of Zn-Co alloy. In this model it was assumed that the Zn(OH)2 was formed during deposition as a consequence of hydrogen evolution, thus raising pH in the vicinity of the cathode. Zinc would deposit via the Zn(OH)2 layer, while cobalt deposition took place by discharge of Co2+ ions... 

Nickel was first refined on a commercial scale at Schneeberg, Saxony, and for some years its chief ores were those occurring in the cobalt deposits of Saxony and Bohemia. In 1838 Swedish pyrrhotite ores were found to contain nickel, and a plant was erected for working them. Nickel was also found in certain Norwegian sulphidie ores, and these soon became the main source of the world s nickel supply, to be superseded in 1877 by the New Caledonian ore, Gamierite. In 1886 sulphidie ores from Sudbury, Ontario, made their appearance on the market, and since 1905 have been the main source of commercial nickel. 

Unfortunately (at least from the point of view of carbonylation), higher levels of H2 give rise to increased rates of formation of homologated products. The reasons for this will be discussed in Section IV,C,2. At very high levels of hydrogen, metallic cobalt deposits from the reaction mixtures. 

Fig. 46). These multilayers were deposited potentiostatically from a single solution containing both Co and Cu ions with a Co Cu ratio of 100 1. The potential of the cathode was pulsed between — 1.40 V (versus SCE) for the cobalt deposition and —0.65 V (versus SCE) for the copper deposition with an s cell potential interrupt between the Co-to-Cu... 

Removal of copper by cementation with cobalt, deposition as sulfide using H2S, solvent extraction, and electrowinning. 

The object of the present study was the application of this approach to the preparation of heterogeneous oxidative catalysts using cobalt phtalocyanine as precursor of cobalt deposited on y-alumina and silica that are traditional supports for oxidative catalysts, and test of the catalysts in partial oxidation of n-butane and toluene. 

Other catalysts have been developed. Cobalt deposited on charcoal is effective in a range of regioselective intramolecular reactions, though a 20 atmosphere pressure of CO must be used.37... 

We will present some results obtained by electrodepositing thin films of Cu, Co and Ni on silicon. Emphasis will be given to different aspects on each case, namely, the morphology and growth rate of copper thin layers, hydrogen evolution during cobalt deposition and structure and electrical properties of nickel layers. 

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