With the chemical symbol Ni, nickel is a silvery white and hard metal which is ductile and malleable and belongs to the transition group of metals. It is a versatile element and will alloy with most metals. The alloys of nickel has been widely used since very early time that meets the compositional standards of the UNS (Unified Numbering System is a specification established by the American Society for Materials and Testing. The UNS assigns a lettered prefix and a five digit number to the metals and their alloys. Specialty nickel and its alloys belong to UNS category such as UNS N02200.
A short history about Nickel
Nickel in its alloyed form with other metals has been used date back to the dawn of civilization and has made significant contributions to our present day society. The nickel was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt. Iron ore limonite which often contains 1-2% nickel is an economically important source of nickel. Its other ore minerals include pentlandite and garnierite. It is considered as a corrosion resistant because of nickel's slow rate of oxidation at room temperature.
Applications of Nickel Alloys
Wide varieties of applications are there for which nickel and its alloys are used. The mostly involve heat resistance and corrosion resistance including medical appliances, chemical and petrochemical industries, aircraft gas turbines, nuclear power system and steam turbine power plants. Other several applications for nickel alloys involve the unique physical properties of high nickel alloys and special purpose nickel base alloys such as soft magnetic alloys, shape memory alloys, low expansion alloys and electrical resistance alloys.
In addition based on its physical and chemical characteristics, applications of nickel are:
Nickel chromium alloys that contain more than about 15% Cr are used in many applications where they are subjected to harsh environment at very high temperature. These alloys are used to provide both carburization resistance and oxidation at temperatures exceeding 760C.
As they offer excellent corrosion resistance to wide range of corrosive media, these are widely used stainless steel.
Copper nickel alloy based tubing is used in desalination plants as this is naturally corrosion resistant to biofouling and by seawater.
Nickel and its alloys are also used in making coins
Its low expansion alloys can be designed to have a very low thermal expansion over certain range of temperature.
Nickel is used in rechargeable batteries such as NiCd (Nickel Cadmium) and in magnets
Its alloys are also used for armour plate and burglar proof vaults.
Properties of Nickel Alloys
Throughout the alloy families, Nickel content ranges from 32.5 to 99.5%. Its alloys are ductile and strong and nickel base super alloys are specified for high temperature and strength at temperature to 2000F. The commercial forms of nickel alloys are fully austenitic and are mainly selected for corrosive resistance feature to high temperature. It is supplied in different forms to their producers such as anode, pellets and powder forms. Its alloys are characterized by high density offering electronic and magnetic property. Furthermore, these offer resistance to corrosion to reducing environments along with some reasonable thermal transfer characteristics.
