nickel

nickel. It is a silvery-white lustrous metal with a slight golden tinge, belonging to the transition metals in group 10 of the periodic table. It is hard, ductile, and ferromagnetic at room temperature, a property it shares with its frequent alloying partner, iron. The element is essential in numerous industrial and consumer applications due to its excellent corrosion resistance and ability to form superalloys.

Properties

Nickel is a hard, malleable, and ductile metal that is a fair conductor of heat and electricity. It possesses a high melting point of 1455 °C and exhibits ferromagnetism up to its Curie temperature of 355 °C, a key characteristic it shares with cobalt and gadolinium. The most common oxidation state is +2, though compounds in states 0, +1, +3, and +4 are known, often stabilized in complexes with ligands like carbon monoxide in Nickel tetracarbonyl. It is highly resistant to corrosion, forming a protective oxide layer, and does not tarnish in air, making it valuable for plating. Its face-centered cubic structure is stable over a wide temperature range, contributing to its strength.

Occurrence and production

Major deposits are found in Canada's Sudbury Basin, Russia's Norilsk, New Caledonia, and Australia's Kambalda region, often associated with magmatic sulfide deposits. Economically important ores include pentlandite and garnierite, with lateritic deposits also being significant sources. The primary production method involves froth flotation, smelting in facilities like the Flash smelting process, and final refining via the Mond process or electrowinning. Leading producers include Norilsk Nickel, Vale S.A., and Glencore, with global output also coming from Indonesia and the Philippines. Recycling from stainless steel scrap and other alloys constitutes a substantial secondary source.

History

Use of nickel-rich meteoric iron dates back to antiquity, with artifacts found in regions like Syria dating to around 3500 BCE. The mineral kupfernickel (false copper) was known to German miners in Saxony, but the element was first isolated and classified by Axel Fredrik Cronstedt in 1751. The development of nickel silver in the 19th century preceded its large-scale use in coinage, notably by the United States Mint in the Shield nickel. The strategic importance of the metal surged during the Second World War, and the 20th century saw the rise of major mining operations in Sudbury, Ontario, following the discovery of ore bodies associated with the Sudbury Basin.

Applications

Approximately 68% of global production is used in stainless steel, such as the common AISI 304 grade. It is critical in superalloys for jet engines and gas turbine blades, produced by companies like General Electric and Rolls-Royce Holdings. Other major uses include electroplating for corrosion protection, found in components from automotive trim to plumbing fixtures. It serves in alnico magnets, rechargeable batteries including NiMH and the chemistry of NiCd, and as a catalyst in processes like the hydrogenation of oils. Coins, such as the Canadian nickel and the United States five-cent piece, have historically contained the metal.

Biological role and toxicity

It is an essential trace element for some organisms, serving as a cofactor for enzymes like urease in plants and certain archaea. In humans, it is not considered essential, and exposure primarily occurs through diet, jewelry, and occupational settings like electroplating shops. Sensitivity can lead to contact dermatitis, a common issue regulated under directives like the Nickel Directive in the European Union. Inhalation of certain compounds, such as dust from nickel refining, is associated with increased risks of respiratory cancers, as noted by the International Agency for Research on Cancer. The Mond process intermediate, Nickel tetracarbonyl, is extremely toxic and a noted chemical warfare agent.

Category:Chemical elements Category:Transition metals