Expansion Alloy Categorization and Invar Alloy Application

Expansion Alloys, also known as heat expansion alloy, are precision alloys with property of anomaly expansion or controllable heat expansion. Common metal or alloy has expansion quantity linearly increased with the temperature enhancement in the situation of heating expansion. However, for some expansion alloys, their heat expansion curve seems bending point at particular temperature, beneath which, the heat expansion coefficient is much reduce than the regular one. So, this phenomenon is known as anomaly heat expansion property and such alloys expansion alloy.

Except for specific heat expansion coefficient, expansion alloy still requires excellent performances like sealing, welding, corrosion resistance and easy cutting based on various functions. In addition, phase transition isn't permitted that leads to obvious alter in expansion property within the range of application temperature. Expansion alloy, in the manufacturing procedure, should precisely manage alloys chemical component. The products are generally bars, plates, belts, wires and tubes extensively applied in fields covering electronic business, precision measuring tool, precision instrument and low temperature engineering.

Within the real application, expansion alloy is mainly divided into low expansion alloy and controlled expansion alloy according to linear expansion coefficient. Controlled Expansion Alloys, like Non Magnetic Controlled Expansion Alloy, are mainly utilized for sealing with subjects like ceramic, glass, silicon and mica, which endows it an additional name, sealing alloy. But low expansion alloy is in quite an additional case. Its expansion or shrinking brought on by magnetostrictive effect below curie point counteracts thermal expansion phenomenon so that the alloy becomes zero expansion or low expansion. Common low expansion alloy is invar alloy, primarily applied in manufacturing resonant cavity in microwave gear, gauge, precision capacitor, gas laser and seismograph.

As the main selection of low expansion alloy, invar alloy has quickly expanded in application field by its characteristic of low expansion coefficient inside a hundred years since its emergency. Precision instrument, rocking beam and balance wheel of etalon clock and gossamer of horologe manufactured from invar alloy became the most important goods within the early period. In 20s, final century, drawing rod utilized in glass sealing that is produced from invar alloy rather than platinum has significantly decreased the cost. When it came to 50s and 60s, invar alloy continued to expand the function to manufacturing wireless electronic tube, thermal bimetallic strip in thermostat, length scale-plate and geodetic surveying base apparatus.( Highly Corrosive Environment))

Arriving 80s and 90s, final century, invar alloy is extensively applied in microwave technology, liquid air container, shadow mask in colour Television, core material of overhead electric wire, resonant cavity, laser collimator chamber, photo-etching camera base plate and all of the like. After it entered 21th century, the new applications include applying in space remote sensing, precision laser, optical measuring system, acting as component in waveguide tube and supporting system of huge lens in microscope and astronomical telescope, as well as applying in various scientific instruments that require installing lens.

All in all, using the constant application of invar alloy in manmade satellite, laser, sound laser gyro as well as other sophisticated high-tech products, it powerfully demonstrates this old material, expansion alloy represented by invar alloy has helped contemporary science advance to a higher level.