The application of rare metal nickel and its alloys

Rare metals possess various excellent properties and thus play an increasingly important role in all sectors of the national economy and various fields of modern science and technology, such as aerospace, energy, electronics, and chemical engineering. In some fields, the application of rare metal materials has even become one of the main factors promoting the development of the field at a certain stage. In aviation and aerospace technology, the application of titanium materials with low density and high high-temperature strength has made it possible to manufacture spacecraft and supersonic aircraft with large Mach numbers.

The reserves of nickel on Earth are very small, only about six percent of those of iron. Moreover, nickel is mixed with various elements and is not easy to extract. Therefore, nickel is relatively expensive. Nickel is an important material for superalloys, with unique corrosion resistance and as an "additive" that significantly improves the properties of metals such as steel. It is widely used.

Nickel is a silvery-white metal with a density of 8.9 g/cm³ and a melting point of 1455℃. It has a face-centered cubic lattice, high strength, good plasticity, poor thermal conductivity and relatively high electrical resistance. Nickel has extremely strong corrosion resistance in air, water, seawater, many salt solutions, organic media, especially various alkaline solutions, due to the formation of a passivation film protective layer on its surface. Its resistance to seawater and hot alkali corrosion is outstanding among metals. Pure nickel is commonly used as a magnetic material and as an alloy for manufacturing stainless steel. It is also employed in vacuum parts and corrosion-resistant parts.

Nickel alloys are formed by adding copper, chromium, aluminum, tungsten, titanium, and other metals to nickel and are used in high-temperature and corrosion-resistant environments. Ni-Cu type alloy, also known as Monel alloy, has no low-temperature brittleness, no magnetism, good weldability and is easy to be formed by cold and hot. It is highly suitable for manufacturing low-temperature equipment, high-temperature equipment resistant to alkali, seawater and hydrofluoric acid corrosion, such as heat exchange equipment, reaction vessels, containers and elastic parts. Ni-Cr type alloys, also known as Innel alloys, have good weldability, cold and hot formability, and corrosion resistance. They also have excellent high-temperature oxidation resistance and outstanding resistance to nitric acid corrosion. It is mainly used for load-bearing parts and equipment that operate at high temperatures, and can also be used to make corrosion-resistant parts, such as heaters, nuclear power evaporators, electric furnace wires, condensers, corrosion-resistant parts of nitric acid production equipment, and high-temperature structural components that operate at around 1000℃, such as turbine blades and gas nozzles of gas turbines. Ni-Mo type alloy, also known as Hastelloy alloy, not only has the ability to resist high-temperature corrosion, but also has excellent comprehensive mechanical properties at high temperatures. It can work at higher temperatures and stresses, and has outstanding resistance to hydrochloric acid corrosion. It is often used in equipment parts that are resistant to hydrochloric acid and other corrosions, as well as in equipment parts that operate at around 650℃ for a long time.