Kovar Material Properties
Kovar is an iron-nickel-cobalt low expansion alloy. By controlling the chemical composition within narrow limits, precise and uniform thermal expansion properties are assured.
With a linear expansion coefficient equal to that of glass and ceramics, Kovar is used for applications requiring a high reliability glass-to-metal or ceramic-to-metal seal with either Pyrex or borosilicate glass and alumina-type ceramic materials. This is particularly useful where resistance to thermal shock is a requirement.
Kovar alloy is magnetic at all temperatures below the Curie point. Magnetic properties are dependent on heat treatment; the lower the hardness, the higher the permeability values.
Applications: Hermetic seals, high-power transmitting valves, transistor leads and headers, integrated-circuit lead frames.
Kovar
| PHYSICAL PROPERTIES | |
|---|---|
| Density | .302 lb/in3 |
| Specific Gravity | 8.36 |
| Melting Point | 2640 °F |
| Curie Temp | 815 °F |
| Composition | Fe 53%, Ni 29%, Co 17% all nominal |
| Mn, Si, C, Cr, Cu, Mo, Al, Mg, Zr, Ti | |
| MECHANICAL PROPERTIES | |
| Tensile Strength | 75,000 PSI |
| Yield Strength | 50,000 PSI |
| Young’s Modulus | 20 x 106 PSI |
| THERMAL PROPERTIES | |
| Thermal Conductivity | 120 BTU-in/sq.ft/hr/°F@77°F |
| Thermal Expansion | 2.9 ppm/°F (75°F to 842°F) |
| Specific Heat | 0.11 BTU/lbm · °F |
| ELECTRICAL PROPERTIES | |
| Electrical Resistivity | 49 µΩ·cm |
