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 | |
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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 |