Nickel (Ni) was discovered in 1751 in Stockholm, Sweden by A.F. Cronstedt from the ore kupfernickel (niccolite).
It is a silver-white metal and mainly occurs in the arsenic and sulfide ores. It is extracted by roasting to NiO and then reducing with carbon. The Mond process is used to manufacture pure nickel, in which impure nickel reacts with carbon monoxide (CO) to form Ni(CO)4, which is then decomposed at 200 °C to yield 99.99% Ni. Nickel has an abundance of 80 ppm in the earth's crust.
It is hard, malleable, ductile and to an extent ferromagnetic (up to 360 °C). It has a fair electrical conductivity (25% that of copper) and heat conductivity. It belongs to the iron-cobalt group of metals. Nickel is highly resistant to atmospheric corrosion and resists most acids, but is attacked by oxidizing acids such as nitric acid.
Natural nickel is a mixture of five stable isotopes, while nine other unstable isotopes are known.
Nickel carbonyl is considered highly toxic and exposure should be very limited. The fumes and dust of nickel sulfide are recognized as having carcinogenic potential.
Owing to its high resistance to corrosion in water or air, pure nickel is used as a protective coating. While it is unaffected by alkalis, it is readily soluble in dilute acids. When it comes to applications, nickel is used as a constituent of different types of alloys; for instance, Monel (corrosion resistant material), Nichrome (an alloy used for resistance heating elements), Permalloy (an alloy with high magnetic permeability at low field strength and low hysteresis loss), cupro-nickel, stainless steel, nickel silver, etc.
In addition, nickel is used as a protective coating, in coinage, and within food and chemical handling plants.
Nickel is classified as a carcinogen and is also an allergen to certain individuals. However, it is found in many dietary constituents, and hence cannot be easily avoided.
Nickel metal has the following applications:
• Its principal use is as an alloying element in stainless steels, alloys steels, non-ferrous metals and other corrosion resistant alloys, examples of which are: Invar®, Monel®, Inconel®, Nichrome®, Permalloy® and the Hastelloys®.
• Nickel coatings can be deposited electrolytically by electroplating, chemically by electroless or autocatalytic deposition.
• Tubing for desalination plants.
• Additives in amour plate and burglarproof vaults metals.
• In glass to produce a green colour.
• As a catalyst for hydrogenating vegetable oils.
• Ceramic manufacturing.
• Alnico magnets.
• Storage batteries, e.g. nickel-cadmium and nickel-metal hydride based batteries. Such batteries are rechargeable and used for mobile phones, personal stereo equipment and the like.
• High purity nickels are used in electronic and aerospace applications, chemical and food processing equipment, for anodes and cathodes, caustics evaporators and heat shields.
• Aircraft turbines components.
• Beryllium nickel is used for springs, switches, bellows, diaphragms and small valves
• Thermometer bulbs and resistance thermometers.
• Glass to metal and ceramic to metal seals.
• Marine, petroleum and chemical processing equipment. (e.g. Monels).
• Incineration systems.
• Controlled expansion nickel superalloys.
• Paramagnetic alloys and shape memory alloys (e.g. Nitinol) are used in fire-sprinkler actuators, tap water anti-scalding devices, green house window hinges, flow regulators, spacecraft solar-panel releases, numerous toys and novelties and under wire brassieres.
Primary author: AZoM.com