Kovar® Bar

Alternative and trade names
Pernifer 2918®, Dilvar P1®, NILO K®
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Description

Kovar is a controlled expansion alloy. It is a nickel iron alloy with 29% nickel, 17% cobalt and the remaining balance is iron. The expansion characteristics of Kovar match both borosilicate (or Pyrex) glasses and alumina ceramics, making it one of the most popular of the controlled expansion alloys for hermetic sealing applications. Kovar is produced to ensure good properties for machining and deep drawing, and is a porosity free product.

Related Standards

Equivalent Materials

This material data has been provided by Matmatch.

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.

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Properties

General

PropertyTemperatureValue

Density

23.0 °C

8.36 g/cm³

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Dimension

PropertyValue

Width

1.6 - 152.4 mm

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Dimensions

Available widths: 1.6mm, 2.4mm, 3.2mm, 4.0mm, 4.8mm, 6.4mm, 8.0mm, 9.5mm, 12.7mm, 15.9mm, 19.1mm, 22.2mm, 25.4mm, 28.6mm, 31.8mm, 34.9mm, 38.1mm, 41.3mm, 44.5mm, 47.6mm, 50.8mm, 57.2mm, 63.8mm, 77.5mm, 88.9mm, 152.4mm

Mechanical

PropertyTemperatureValueComment

Elastic modulus

23.0 °C

207 GPa

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Elongation

23.0 °C

30 %

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in 2 in.

Hardness, Rockwell B

23.0 °C

80 [-]

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Tensile strength

23.0 °C

518 MPa

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Yield strength

23.0 °C

276 MPa

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Thermal

PropertyTemperatureValueComment

Coefficient of thermal expansion

100.0 °C

5.8E-6 1/K

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from 30°C to the mentioned temperature

150.0 °C

5.6E-6 1/K

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from 30°C to the mentioned temperature

200.0 °C

5.4E-6 1/K

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from 30°C to the mentioned temperature

250.0 °C

5.3E-6 1/K

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from 30°C to the mentioned temperature

300.0 °C

5.1E-6 1/K

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from 30°C to the mentioned temperature

350.0 °C

4.9E-6 1/K

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from 30°C to the mentioned temperature

400.0 °C

4.6E-6 - 5.2E-6 1/K

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from 30°C to the mentioned temperature

450.0 °C

5.1E-6 - 5.5E-6 1/K

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from 30°C to the mentioned temperature

500.0 °C

6.1E-6 1/K

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from 30°C to the mentioned temperature

550.0 °C

6.8E-6 1/K

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from 30°C to the mentioned temperature

600.0 °C

7.5E-6 1/K

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from 30°C to the mentioned temperature

700.0 °C

8.7E-6 1/K

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from 30°C to the mentioned temperature

800.0 °C

1.03E-5 1/K

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from 30°C to the mentioned temperature

900.0 °C

1.08E-5 1/K

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from 30°C to the mentioned temperature

1000.0 °C

1.17E-5 1/K

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from 30°C to the mentioned temperature

Melting point

1449 °C

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Specific heat capacity

23.0 °C

460 J/(kg·K)

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Thermal conductivity

23.0 °C

17 W/(m·K)

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Electrical

PropertyTemperatureValue

Electrical resistivity

23.0 °C

4E-7 Ω·m

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Magnetic

PropertyValue

Curie temperature

435 °C

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Chemical properties

PropertyValue

Carbon

0.02 %

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Chromium

0.2 %

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Cobalt

17 %

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Iron

Balance

Nickel

29 %

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Silicon

0.2 %

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Technological properties

Property
Application areas

Common applications of Kovar: Glass-to-metal hermetic sealing with hard borosilicate glass, ceramic-to-metal sealing, power tubes, microwave tubes, transistors, diodes, integrated circuits, hybrid packages