Nickel Round Bar Kovar is a nickel-cobalt-iron alloy designed for applications requiring a controlled thermal expansion coefficient matching certain glass, ceramic, and other materials. Its unique composition allows it to form vacuum-tight seals between metals and non-metallic components, making it invaluable in the manufacture of vacuum tubes, glass-to-metal seals, and other products where preventing leaks from differing thermal expansions is critical. While specialized, Kovar's tailored properties make it an essential material for a range of electronic, vacuum, and sealing applications.