Glass sealed and controllled expansion alloys
*kovar alloy, Standard:ASTM F15, Nilo-K, UNS K94610 (FeNi29Co17), Chinese 4J29
*Specifications:ASTM F15; DIN 17745; S.E.W. 385; Werkstoff Nr. 1.3981; AFNOR NF A54-301
Note: A Nickel-Iron-Cobalt, controlled expansion alloy containing 29% Nickel 17%Cobalt.
It’s coefficient of expansion (which decreases with rising temperature to the inflection point), matches the expansion rate of borosilicate glasses and aluminia ceramics.Applications include glass to metal seals in applications requiring high reliability or resistance to thermal shock, ie. highpower transmitting valves, transistor leads and heaters and photography flash bulbs.
Table 1 Grade & Chemical Composition
Kovar alloy is a vacuum melted, Iron-nickel-cobalt, low expansion alloy whose chemical composition is controlled within narrow limits to assure precise uniform thermal expansion properties.
Grade | Chemical Composition (%) | ||||||||||
C | P | S | Mn | Si | Cu | Cr | Mo | Ni | Co | Fe | |
4J29 Kovar | ≤ | ||||||||||
0.03 | 0.020 | 0.020 | 0.5 | 0.30 | 0.20 | 0.20 | 0.20 | 28.5~29.5 | 16.8~17.8 | Bal. | |
Chinese 4J29 Similar Grades just for customers’ reference
Russia | U.S.A. | U.K. | France | Germany |
29HK | Kovar | Nilo K | Dilver P0 | Vacon 12 |
Physical Property (see Table 2 & Table 3)
Table 2 Coefficient of Linear Expansion
Note: Kovar alloy is a Glass and Ceramic sealing alloy (Glass to metal sealing and Ceramic to metal sealing).
Grade | Heat Treatment of the Samples | Average Coefficient of Linear Expansion | ||
20~300℃ | 20~400℃ | 20~450°C | ||
4J29 Kovar | Heat to temperature of 900±20℃ in the hydrogen, hold for 1h; re-heat to 1100±20℃, hold for 15 min.; cooled to 200℃ at a rate less than 5℃/min |
| 4.6~5.2 | 5.1~5.5 |
Table 3 Typical Coefficient of Linear Expansion
Grade | Average Coefficient of Linear Expansion | |||||||
20~200℃ | 20~300℃ | 20~400℃ | 20~450℃ | 20~500℃ | 20~600℃ | 20~700℃ | 20~800℃ | |
4J29 Kovar | 5.9 | 5.3 | 5.1 | 5.3 | 6.2 | 7.8 | 9.2 | 10.2 |
Applications
Kovar alloy 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 intergrated circuits, it has been used for the flat pack and the dual-in-line package.
Specification: Sheet/Plate, Bar/Rod/Wire/Coil,Capillary/Pipe/Tube
Note: We could do any other products with specified technical standard, say, ASTM,SAE,DIN,S.E.W.,JIS,ISO,IEC,NF,BS.PLS contact us for more information:
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