Kovar is a Ni-Fe alloy with 29% Nickel, 17% Cobalt and the remaining balance is Iron. The expansion characteristics of Kovar match both borosilicate (or Pyrex) glasses and alumina ceramics, making it one of the most popular of the controlled expansion alloys for hermetic sealing applications.
Character
Kovar alloy is magnetic at all temperatures below the Curie point. Magnetic properties will depend upon heat treatment; the lower the hardness, the higher the permeability values and lower hysteresis loss.
Density: 8.36g/cm3
Curie Temp: 435°C(815°F)
Application
Kovar is widely used in applications such as power tubes, microwave tubes, transistors, diodes, hybrid packages, and other kinds of scientific instruments.