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Expansion Precision Alloy 4J29 (Ni29Co18) UNS K94610 Electric Vacuum Kovar Strip Tube Bar Wire Plate
OhmAlloy-4J29 (Expansion alloy)
(Common Name: Kovar, Nilo K, KV-1, Dilver Po, Vacon 12)
OhmAlloy-4J29 also known as Kovar alloy. it was invented to meet
the need for a reliable glass-to-metal seal, which is required in
electronic devices such as light bulbs, vacuum tubes, cathode ray
tubes, and in vacuum systems in chemistry and other scientific
research. Most metals cannot seal to glass because their
coefficient of thermal expansion is not the same as glass, so as
the joint cools after fabrication the stresses due to the
differential expansion rates of the glass and metal cause the joint
to crack.
Chemical Composition
Grade | C% | P% | S% | Mn% | Si% | Cu% | Cr% | Mo% | Ni% | Co% | Fe% |
Kovar | Max 0.03 | Max 0.020 | Max 0.020 | Max 0.50 | Max 0.30 | Max 0.20 | Max 0.20 | Max 0.20 | 28.5-29.5 | 16.8-17.8 | Bal. |
Specifications
Grade | UNS | Werkstoff Nr. |
Kovar | K94610 | 1.3981 |
Physical Properties
Grade | Density | Melting Point |
Kovar | 8.17 g/cm3 | 1449°C |
Mechanical Properties
Grade | Tensile Strength N/mm² | ||||
Soft | 1/4 Hard | 1/2 Hard | 3/4 Hard | Full Hard | |
Kovar Strip | <570 | 520-630 | 590-700 | 600-770 | >700 |
Kovar Wire | <585 | 585-725 | 655-795 | 725-860 | >860 |
Coefficient of Expansion
Alloy | Linear Coefficient of Thermal Expansion a,10-6/°C | |||||||
20-200°C | 20-300°C | 20-400°C | 20-450°C | 20-500°C | 20-600°C | 20-700°C | 20-800°C | |
Kovar | 5.9 | 5.3 | 5.1 | 5.3 | 6.2 | 7.8 | 9.2 | 10.2 |
Package