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.

Chinese 4J29 Similar Grades just for customers’ reference

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).

Table 3 Typical Coefficient of Linear Expansion

                                                           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

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