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Kovar Material Suppliers

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).

City Special Metals manufacture a variety of Kovar Alloy Products, including Kovar Plates, Bars and Saws. As well as Kovar, we are also widely known as Europe's largest stockist of low and controlled expansion alloys. Discuss your requirements by contacting our team today.

Kovar Stockist Range

Product FormRange FromRange To
Kovar Plate4mm210mm
Kovar Round Bar4mm160mm
Kovar Sheet & Coil0.025mm3.175mm
Kovar Wire0.1mm3.175mm
Kovar Tube3.175x0.254mm25.4x1.0mm

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Kovar Alloy Products & Properties

As experienced manufacturers of this metal, as well as a great many others also, we’ve got plenty to say. Would you like to read more about Kovar®? Find Everything you Need to Know here.

If you’d also like more information about the Machinability of Kovar®, read our blog article here: Kovar – Machinability Information.

Ready to enquire with City Special Metals? We’re Europe’s leading speciality metals stockists and always happy to help. Skip to our contact form below, fill in some details and also tell us about your manufacturing requirements. Click here to do that.

Alternatively, below is information on the Applications, Products and Properties of this versatile controlled expansion alloy.

Beneficial Properties

  • Expansion Control Reliable hermetic sealing applications
  • Uniformity Precise and uniform thermal expansion characteristics
  • Shock-resistant Their coefficient thermal expansion makes the seal resistant to shock and cracking

Markets & Applications

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

Kovar Mechanical Properties

Metallurgical ConditionAnnealed, Descaled
Yield StrengthKSI (MPa)40 (276)
Tensile StrengthKSI (MPa)75 (518)

Kovar Technical Specifications

F15K946101.3981I-23011 CL1

Kovar Chemistry


Kovar Physical Properties

Co Efficient of Thermal Expansion
20-100°C10-6/°C0.8 - 1.7
20-200°C10-6/°C2.2 – 2.9
Curie Temp°F815
Melting Point°F2640
Modulus of Elasticity at 20°CMPa207
Specific HeatJ/g- °C0.11
Thermal Conductivity at 20°CW/m.k17.3
Thermal ExpansionW.m-¹°C0.17
Electrical Resistivitymm²/m49
Poisson's coefficient0.317

We offer a bespoke service so, if you don’t see the size or form that you require, contact us either by phone, email or our contact form below, and we will provide a solution to your requirements.

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. In 2019 and beyond, City Special Metals serve to manufacture Kovar to the highest standard. You can learn more about our Quality Assurances here.

Kovar is also known by the following trade names

  • Kovar®
  • Pernifer 29-18®
  • Dilaton 29-18® Dilver P®
  • Dilver® NiCoFe®
  • Telcoseal 1®
  • Sealvar®
  • Nilo K®
  • Nicoseal®
  • Nicosel®
  • Therlo®
  • FeNi29Co17®