Nickel natural alloys

The processes involved in the reduction of nickel ores vary considerably, both with the chemical composition of the ore employed and the nature of the product required. For example, the Sudbury (Ontario) ores consist essentially of sulphides of nickel, copper, and iron. When pure nickel is required it is, of course, essential to remove the copper and the iron. Sometimes, however, an alloy of nickel and copper, known as monel metal, is desired, and it is usual then to remove the iron and subsequently reduce the mixed sulphides of copper and nickel to the alloy direct. Monel metal is thus known as a natural alloy, inasmuch as the constituent elements have not been individually isolated. 

A very important alloy containing 25 per cent, of nickel and 75 per cent, of copper finds extensive application in the manufacture of currency both in Europe and in the New World. Reference has already been made to this in previous pages.1 Monel metal is an alloy of nickel and copper made by the Orford Copper Company by direct reduction of the nickel-copper matte obtained from the Sudbury ores (see p. 82). It is therefore termed a natural alloy. It contains from 60-72 per cent, of nickel, the remainder consisting mainly of copper with iron ranging from 0-5 to 6-5 per cent. The United States Government specification, issued in July 1910, for monel metal requires 8... 

Olefinic acids have been reduced to saturated acids in excellent yields by a variety of methods. Catalytic hydrogenation at room temperature over platinum oxide catalyst is described for 4-phenyl-3-pentenoic acid (98%). Behenic and undecanoic acids are prepared from the naturally occurring erucic and undecylenic acids with this catalyst. New and "aged platinum oxide catalysts have been compared, Reduction by nickel-aluminum alloy has been preferred to catalytic hydrogenation over platinum catalyst in the preparation of y-isopropylvaleric acid. ... 

Next-generation metallic biomaterials include porous titanium alloys and porous CoCrMo with elastic moduli that more closely mimic that of human bone nickel-titanium alloys with shape-memory properties for dental braces and medical staples rare earth magnets such as the NdFeB family for dental fixatives and titanium alloys or stainless steel coated with hydroxyapatite for improved bioactivity for bone replacement. The corrosion resistance, biocompatibility, and mechanical properties of many of these materials still must be optimized for example, the toxicity and carcinogenic nature of nickel released from NiTi alloys is a concern. ... 

The nature of the corrosion scale is very important in deciding the corrosion resistance of the component. Surface modification or alloying alters the composition and complexity of the corrosion scales, which prevents further corrosion and outward diffusion of alloy components. Vossen et al. have shown the complex scale formation in the case of stainless steel and nickel-based alloys in comparison to pure metals.These scales are understood to cause transport problems to the outward diffusion of alloy components and thereby decrease the dissolution of the steel components. Therefore, any improvement to the corrosion resistant properties of the current collector has to come by way... 

K. Tachibana and M.B. Ives, Selective Dissolution Measurements to Determine the Nature of Films on Nickel-Molybdenum Alloys, Passivity of Metals, The Electrochemical Society, 1978, p 878-897... 

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