Kovar,  which finds application in glass-to-metal seals in scientific apparatus, and conductors entering glass envelopes of electronic parts, has a density of  8.0g /cm, hardness of 160 HV1, and Curie temperature of 435 C.
Kovar (trademark of CRS Holdings, inc., Delaware) is a nickelcobalt ferrous alloy compositionally identical to Fernico 1, designed to have substantially the same thermal expansion characteristics as borosilicate glass (~5  10 /K between 30 and 200 C, to ~10  10 /K at 800 C) to allow a tight mechanical joint between the two materials over a range of temperatures. It finds application in glass-to-metal seals in scientific apparatus, and conductors entering glass envelopes of electronic parts such as vacuum tubes (valves), X-ray and microwave tubes and some lightbulbs. Density g /cm 8.0 Hardness / HV1 160 Curie Temperature / C 435 
