an iron-based alloy containing 18 percent cobalt and 29 percent nickel. Kovar is characterized by a low coefficient of thermal expansion [(4.5–5.2) X 10^-6 1/°C between 20° and 400°C], approximating the coefficient of thermal expansion of glass. Melting point, 1450°C; specific electrical resistance, 0.5 microhm · m; Curie temperature, 420°C. The alloy corrodes in a moist medium and requires protective coatings. When sealed in glass, Kovar forms a strong vacuum-tight adhesion, which is used in electrical engineering for the manufacture of casings and current outlets in various tubes and devices.