Kovar Material Manufacturer and Supplier

Kovar Material Manufacturer and Supplier

Kovar is a nickel-iron-cobalt, controlled expansion alloy. 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). Brilliance Special Steel manufactures a variety of Kovar Alloy Products, including Kovar Plates, Bars,Wire,etc.

Kovar Mechanical Properties

Metallurgical Condition  Annealed, Descaled     

Yield Strength    KSI (MPa)       40 (276)

Tensile Strength    KSI (MPa)       75 (518)

Hardness HB   78

Elongation     50mm     >20

Kovar Chemistry

Nickel     Ni    29

Cobalt    Co   17

Iron Fe    Balance

Manganese    Mn  0.5

Silicon     Si     0.2

Carbon   C     0.04

Kovar Physical Properties

Co-efficient of Thermal Expansion            

20-100°C       10-6/°C  0.8 - 1.7

20-200°C       10-6/°C  2.2 – 2.9

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

A Versatile Controlled Expansion Alloy

Kovar has been in use for many decades as a controlled expansion alloy. However, despite its relatively long history, many people outside the engineering industry have never heard of Kovar.

What makes Kovar so unique is it's coefficient of thermal expansion. As a controlled expansion alloy, it shared some remarkable similarities to borosilicate glass (hard glass) and ceramic.

Kovar's coefficient of thermal expansion is not an accident, though. Going back in history, Kovar was carefully formulated to meet a specific need.