Controlled expansion alloys are often used in applications where metals must form a hermetic seal with glass or ceramic. In order to prevent the glass or ceramic from cracking, the thermal expansion characteristics of the alloy must closely match the thermal expansion characteristics of the glass or ceramic to prevent undue stress as the material expands and contracts as the assembly is heated and cooled.
Typical applications for hermetic seals include: vacuum tubes, lamps, power tubes, microwave tubes, transistors, switches and integrated circuits (Chips).
In addition, controlled expansion alloys are used where a specific expansion must be met over a certain temperature range. This often includes a minimum expansion requirement around ambient temperature. Invar 36 is often selected for this application. Controlled expansion alloys can be used in optoelectronics, optical and laser benches, and other scientific instruments.
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Electrical/Electronic Nickel
Commercially pure nickel contains only traces of minor elements. Available in several grades, pure nickel has good mechanical properties and excellent resistance to many corrosive environments. Other features include high thermal and electrical conductivities which is often desirable in electronic applications. This material is often used in electrical and electronics parts. Typical applications include: components for electronics packaging such as, leads, terminals, getter tabs, and lids. It used as anodes, cathodes, and shields in special purpose electron tubes. It is also needed in fuel cells and Ni-Cd batteries as well as applications where corrosion resistance is a necessity.