Kovar alloy is a iron-nickel-cobalt, low expansion alloy whose chemical composition is controlled within narrow limits to assure precise uniform thermal expansion properties. Kovar alloy has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials.
Kovar Specification
| ASTM | UNS | W.Nr |
| F15 | K94610 | 1.3981 |
Kovar Chemical composition
| Grade | % | Ni | Cr | Fe | Co | Cu | C | Mn | Si | P | S | Mo |
| Kovar | Min | 28.5 | Bal. | 16.8 | ||||||||
| Max | 29.5 | 0.2 | 17.8 | 0.20 | 0.03 | 0.50 | 0.30 | 0.02 | 0.02 | 0.20 |
Kovar Coefficient of linear expansion
| Grade | a/10-6·K-1 | ||
| Kovar | 200-300℃ | 20-400℃ | 20-450℃ |
| / | 4.6-5.2 | 5.1-5.5 | |
