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Everything You Wanted To Know About Dumet Wire

Controlled Expansion Materials

Controlled expansion materials are Iron-Nickel alloys that were developed to exhibit a coefficient of thermal expansion within certain ranges.  The purpose of the controlled expansion is to insure good mating and/or seals when mating with other materials.  Controlled expansion alloys that have a thermal expansion coefficient that is similar to glass are commonly referred to as Glass Sealing alloys.

JLC Electromet offers many alloys for Controlled Expansion and Glass Sealing applications.  We are capable of offering Alloy 36 (Invar “36”® (® = Registered Trademark of Carpenter Technology Corporation), Alloy 42,  Alloy 52, Dumet and Kovar® (® = Registered Trademark of Corning Glass).
Controlled expansion alloys and glass sealing alloys are available in two categories:

  1. Alloys having a very low expansion coefficient within a certain temperature range are classified as Low Thermal Expansion alloys.  Electronic devices and thermostats commonly use the low expansion alloys such as Alloy 36 and Alloy 42. Kovar, another low expansion alloy, can provide a strong hermetic seal to hard borosilicate glasses and ceramic materials. 
  2. Alloys that offer the same expansion coefficients as the glass or ceramic that they are being used with are referred to as Matching Expansion.  Matching Expansion alloys are commonly used in the electronics industry.  The most common alloys with Matching Expansion would be Alloy 42 or Alloy 52.
  3. Alloy 36 has the lowest thermal expansion coefficient of the Iron-Nickel Alloys.  Alloy 36 is available in diameter size of .0005” to .025” in wire form.  Alloy 42 is offered in diameter sizes .001” to .020”.  Alloy 52 is available in diameter sizes of .0005” to .060” and the size range for Dumet and Kovar is .001” to .040”.  All these materials are also available as stranded and insulated or as ribbon.
  4. Dumet is a glass sealing alloys used for lamps.  Dumet has a Nickel Iron core with a Copper cladding.  In addition to Kovar, we offer other alloys that can be used for glass sealing such as OFHC Copper, Molybdenum, Nickel A/200, Nickel 205 or Nickel 211.