Fernico

Fernico represents a group of a plurality of slightly different alloy of iron (Fe ), nickel (Ni) and cobalt (Co), having a wide temperature range, a similar low thermal expansion such as the borosilicate glass used technically. Fernico is used inter alia to realize the electrical connections in the evacuated glass envelope of electron tubes. With the use of metals having a glass to markedly different thermal expansion characteristics, there would otherwise when the temperature changes at the interface between the metallic glass and performing body to crack and thus to an unwanted entry of air into the electron tube.

The term Fernico provides up to the letter " R " is the chemical names of the alloy constituents and was originally a brand name of General Electric Company.

There are used two forms of this alloy, in weight percent, the alloys have the following shares:

Both alloys have a similar coefficient of thermal expansion of about 5 ppm and also exhibit permanent magnetic properties. However, they are hardly used alternatives as a permanent magnet material due to better.

Fernico I is also known as Kovar. In addition, there are other specialty alloys with similar applications as Cunife, which are based on copper as a main component and nickel, and iron.