Characteristics nickel iron

The treatments used to recover nickel from its sulfide and lateritic ores differ considerably because of the differing physical characteristics of the two ore types. The sulfide ores, in which the nickel, iron, and copper occur in a physical mixture as distinct minerals, are amenable to initial concentration by mechanical methods, eg, flotation (qv) and magnetic separation (see SEPARATION,MAGNETIC). The lateritic ores are not susceptible to these physical processes of beneficiation, and chemical means must be used to extract the nickel. The nickel concentration processes that have been developed are not as effective for the lateritic ores as for the sulfide ores (see also Metallurgy, extractive Minerals recovery and processing). 

Fig. 10. Power and voltage characteristics of the nickel—iron cell where the internal resistance of the cell, R, is 0.70 mQ, at various states of discharge ( )...

Nickel-iron alloys have a number of important applications that are derived from such special physical properties as their unique magnetic characteristics in the regions of 35, 50 and 80% nickel and from their abnormally low thermal expansion in the region of 36-50% nickel. Although not specifically used as corrosion-resistant materials, their high resistance to attack from many common environments is of benefit in their specialised applications. 

In zinc metalloenzymes. zinc is a selective stoichiometric constituent and is essential for catalytic activity. It is frequently present in numerical correspondence with the number of active enzymatic sites, coenzyme binding sites, or enzyme subunits Removal of zinc results in loss of activity. Inhibition by metal complexing agents is a characteristic feature of zinc metalloenzymes. However, no direct relationship holds between the inhibitory effectiveness of these agents and their affinity for ionic zinc. Although zinc is the only constituent of zinc metalloenzymes in vivo, it can be replaced by other metals m vitro, such as cobalt, nickel, iron, manganese, cadmium, mercury, and lead, as m the case of carboxy-peprida.ses. 

A crucial problem connected to carbon nanotube synthesis on supported catalysts on an industrial scale is the purification step required to remove the support and possibly the catalyst from the final material. To avoid this costly operation, the use of CNT- or CNF-supported catalysts to produce CNTs or CNFs has been investigated. Although most catalytic systems are based on nickel supported on CNFs (see Table 9.4), the use of MWCNTs [305,306] or SWCNTs [307] as supports has also been reported. Nickel, iron [304,308-310], and bimetallic Fe-Mo [305] and Ni-Pd [295] catalysts have been used. Compared to the starting CNTs or CNFs, the hybrid materials produced present higher specific surface area [297,308] or improved field emission characteristics [309]. 

The nickel electrode serves as cathode for several important commercial rechargeable battery systems. The characteristics of these systems are hsted in Table 13.1. The hist commercial nickel battery was the nickel-iron system which provided lighting in railroad cars due to its strong resistance to physical and electrical abuse. The electrode structure has a strong influence on the operating life of a battery system. The nickel systems are robust, both physically and chenucally. 

The nickel-iron battery cell fabrication process is essentially unchanged in over 50 years. Special attention must be paid to use high purity materials and particle size characteristics of the active materials. The iron negative active material is made from pure iron that is dissolved in sulfuric acid. The resulting Fe(S04>2 is recrystallized and dried. This is washed free of sulfuric acid and roasted at 915°C to form a mixture of FeaOs and Fe metal and is, then, blended with small amotmts of FeS, sulfur, and HgO for use in the negative plate assembly. 

Hill TE, Rosy R, Vaill RE (1978) Performance characteristics of iron nickel batteries. In Proceedings of the 28th power sources symposium. Electrochemical Society, Pennington, p 149... 

The term superalloy is used for a group of nickel-, iron-nickel-, and cobalt-based high-temperature materials for applications at temperatures > 540 °C. It is useful to compare the main subgroups in terms of the strengthening mechanisms applied and stress-rupture characteristics achieved, as shown in Fig. 3.1-127. In this section iron-nickel- and nickel-based superalloys are covered whereas cobalt-based superalloys are dealt with in Sect. 3.1.6.3. Nickel-based superalloys are among the most complex metallic materials with numerous alloying elements serving particular functions, as briefly outlined here. 

In the case of the synthesis of alumina, chrome, nickel, iron and nanocrystalline cobalt oxides using the solution combustion technique, for example, we lack, so far, a deep understanding of the influence of the fuel-oxidant ratios well as a model of the thermodynamic variables associated with enthalpy, adiabatic flame temperature and the total number of moles of gas generated related to the powder characteristics, such as crystallite size and surface area. 

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