General Description

Kovar is a nominal 29%Ni-17%Co-54%Fe alloy that is a well-known glass-sealing alloy suitable for sealing to hard glasses. Kovar has a nominal expansion coefficient of approximately 5 ppm/°C and inflection temperature of ~450 °C (840 °F).

Kovar (ASTM F15) has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials. This alloy has found wide application in power tubes, microwave tubes, transistors, and diodes. In integrated circuits, it has been used for the flat pack and the dual-in-line package.

Chemical Composition

Grade C% P% S% Mn% Si% Cu% Cr% Mo% Co% Ni% Fe%
Kovar Alloy Max 0.03 Max 0.02 Max 0.02 Max 0.50 Max 0.30 Max 0.20 Max 0.20 Max 0.20 16.8-17.8 28.5-29.5 Bal.


UNS K94610

Werkstoff Nr. 1.3981


Strip/Sheet  ASTM F15

Bar, Kovar thin wall tube is available per request

Physical Properties

Density: 8.17 g/cm3

Melting Point: 1449°C

Mechanical Properties

Form Soft 1/4 Hard 1/2 Hard 3/4 Hard Full Hard
Kovar Strip Max 570 520-630 590-900 600-770 Min 700
Kovar Wire Max 585 585-725 655-795 725-860 Min 860

Linear Coefficient of Thermal Expansion ā,10-6/℃

Grade 20-200℃ 20-300℃ 20-400℃ 20-450℃ 20-500℃ 20-600℃ 20-700℃ 20-800℃
Kovar Alloy 5.9 5.3 5.1 5.3 6.2 7.8 9.2 10.2

Find out more about Kovar capillary tube on the our website.

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