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Kovar (Nilo®, Alloy K) / 1.3981 / UNS K94610

Kovar® is a nickel-iron-cobalt alloy with a coefficient of thermal expansion like that of hard glass. Since Kovar Alloy is tough and versatile, while employing extensive quality controls throughout UNS K94610 alloy’s manufacturing process to ensure uniform physical and mechanical properties for ease in deep drawing, stamping and machining are consistently achieved. Furthermore, the coefficient of thermal expansion (CTE) of Kovar® is its most dynamic mechanical property. It's expansion characteristics match both borosilicate (or Pyrex) glasses and alumina ceramics. This alone ensures it is a highly popular controlled expansion alloys for hermetic sealing applications (also known as Glass to Metals Sealing).

Material Data Sheet

UNS K94610
AMS I-23011 CL1

Main fields of application

Kovar is used for:

  • Hermetic sealing
  • Production of transistors and diodes in electronic industry
  • Vacuum systems in chemistry and scientific research
  • Electronic tubes (power, microwave, X-Ray)
  • Hybrid circuit casings
  • Oscillator housings
  • Concentrated solar power
  • Scientific instruments


Chemical composition of Kovar

Ni Co Fe Mn Si C
29 17 Balance 0.5 0.2 0.04

Mechanical properties of Kovar

Density g/cm³ 8.26  
Curie Temp °F 815 °C 435
Melting Point °F 2640 °C 1449
Modulus of Elasticity at 20°C MPa 207
Specific Heat J/g- °C 0.11
Thermal Conductivity at 20°C W/m.k 17.3
Thermal Expansion W.m-¹°C 0.17
Electrical Resistivity mm²/m 49
Poisson's coefficient 0.317  

Delivery program

Material is mainly used in bars or as wire. Various dimensions are available upon request.

Material Outlet by Hempel

ECONOXX.com offers buyers a new and uncomplicated procurement channel, which also includes small quantities and materials in special alloys at favourable conditions.

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