Kovar alloy

Alloy 29-17, UNS K94610, K94630, 1.3981, Kovar®, Nilo® Alloy K, 4J29, Fe53-Ni29-Co17

Alloy 29-17 is a a vacuum melted nickel-iron-cobalt low expansion alloy containing approximately 29% nickel and 17% cobalt. Its chemical composition is controlled within narrow limits to assure precise uniform thermal expansion properties. Extensive quality controls are employed in the manufacture of this alloy to ensure uniform physical and mechanical properties for ease in deep drawing, coining, stamping and machining.

Alloy 29-17 thermal expansion characteristics match those of borosilicate glasses and alumina type ceramics. It is manufactured to a close chemistry range, yielding repeatable properties which make it eminently suitable for glass-to-metal seals in mass production applications, or where reliability is of paramount importance.

Alloy 29-17 is a nickel-iron-cobalt alloy which exhibit low expansion at room temperature. They have a coefficient of thermal expansion similar to that of glass. Therefore these types of alloys are used in many glass to metal and hermetic sealing applications.
Alloy 29-17 has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials. This alloy has found wide use in application where high reliability is a necessity. In power tubes, x-ray tubes, lighting tubes, microwave tubes, vacuum tubes, transistors, diodes, photography flash bulbs and intergrated circuits such as flat pack, the dual-in-line package and optoelectronic component cases and bases. The alloy is also frequently used in the telecommunications, military and defense, aerospace and electronic industries.

Alloy 29-17 is non-hardenable by heat treatment.
The alloy is normally used in the annealed condition, attained by heating, preferably in hydrogen or cracked ammonia, to 850-1000°C (1560-1830°F).
Decarburization to prepare for glass-to-metal sealing is usually carried out in an atmosphere of wet hydrogen at 900- 1050°C (1650-1920°F) for 1 hour. For seals requiring a metal oxide interface, the alloy can be oxidized by heating in air to temperatures in the 600-1000°C (1110-1830°F) range, depending on the thickness of oxide film required.

Alloy 29-17 can be hot or cold worked, machined and formed by processes similar to those used for austenitic stainless steels.

Cold worked and bright annealed

Cold worked, bright annealed, polished (MP, EP etc.)

Capillary tube

• _◎ OD 0.30 ~ 3.0 mm
• _◎ WT 0.05 ~ 0.5 mm

Precision seamless tube

• _◎ OD 3.0 ~ 89 mm
• _◎ WT 0.10 ~ 10.0 mm

HP / UHP BA+ tube

• _◎ OD 3.0 ~ 76 mm
• _◎ WT 0.10 ~ 10.0 mm