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Kanthal (alloy)

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Kanthal is the trademark for a family of iron-chromium-aluminium (FeCrAl) alloys used in a wide range of resistance and high-temperature applications. Kanthal FeCrAl alloys consist of mainly iron, chromium (20–30%) and aluminium (4–7.5 %). The first Kanthal FeCrAl alloy was developed by Hans von Kantzow in Hallstahammar, Sweden. The alloys are known for their ability to withstand high temperatures and having intermediate electric resistance. As such, it is frequently used in heating elements. The trademark Kanthal is owned by Sandvik Intellectual Property AB.

Characteristics

For heating, resistance wire must be stable in air when hot. Kanthal FeCrAl alloy forms a protective layer of aluminium oxide (alumina).[1] Aluminium oxide has high thermal conductivity but is an electrical insulator, so special techniques may be required to make good electrical connections.

Ordinary Kanthal FeCrAl alloy has a melting point of 1,425 °C (2,597 °F). Special grades can be used as high as 1,500 °C (2,730 °F).[2]

Depending on specific composition the resistivity is about 1.4 μΩ·m and temperature coefficient is +49 ppm/K (+49×10−6 K−1).

Uses

Kanthal is used in heating elements due to its flexibility, durability and tensile strength. Its uses are widespread, for example in toasters, home and industrial heaters, kilns and diffusion heaters (used in the making of crystalline silicon).[3][4]

Recently, Kanthal has been used for heating coils in electronic cigarettes. Unlike alternative types of metal such as Nichrome, Kanthal is durable enough to withstand the temperatures needed, but flexible and cheap enough to be practical.[5]

Kanthal comes in standardised gauging, with higher numbers being thinner and lower being thicker.

See also

References

  1. ^ "Advanced Topic: Oxidation Resistant Materials" (PDF). Archived from the original (PDF) on 2005-03-20.
  2. ^ US 7027722, Uemori, Susumu & Aitani, Takashi, "Electric heater for a semiconductor processing apparatus", issued 2006-04-11 
  3. ^ "Kanthal heating technology products — Kanthal". www.kanthal.com. Retrieved 2017-01-04.
  4. ^ Harlay, Jérôme (2016-03-08). "A chemist's advice: Don't Dry-Burn your coil". Vaping Post. Retrieved 2017-01-04.
  5. ^ misthub.com. "Tutorial: NiChrome vs Ni-200 vs Titanium vs Kanthal vs Stainless Steel | MistHub". www.misthub.com. Retrieved 2017-01-04.
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