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Kovar Material Suppliers

Kovar alloy 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 Sheets. 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 Plate icon

Kovar Plate

Kovar Round Bar icon

Kovar Round Bar

Kovar Sheet & Coil icon

Kovar Sheet & Coil

Kovar Wire icon

Kovar Wire

Kovar Tube icon

Kovar Tube


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    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
    Call City Special Metals +44 1268 774 261

    Kovar Composition

    Mechanical Properties

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

    Technical Specifications

    F15K946101.3981I-23011 CL1



    Physical Properties

    Co Efficient of Thermal Expansion
    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

    Kovar Alloy Products & Properties

    City Special Metals stock and supply a wide range of kovar products and materials. Therefore, it should be no surprise that we know a lot about Alloy K too.

    Head over to our insights pages if you’d like ro read more about Kovar. We’ve written features about the Machinability of Kovar®, plus much more.

    Ready to enquire with City Special Metals? We’re a leading UK based speciality metals stockist and always happy to help. Skip to our contact form below, fill in some details and also tell us about your Kovar Material Requirements requirements. Click here to skip down the page. 

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

    Call City Special Metals +44 1268 774 261

    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®