Chromel

Chromel is an alloy made of approximately 90 percent nickel and 10 percent chromium that is used to make the positive conductors of ANSI Type E (chromel-constantan) and K (chromel-alumel) thermocouples. It can be used at temperatures up to 1100 °C in oxidizing atmospheres. Chromel is a registered trademark of Concept Alloys, Inc.[1]

Characteristics and properties of chromel (90%-10% Ni-Cr)
CHARACTERISTICS:
Temperature coefficient 0.00032 K−1
Electrical resistivity 0.706 µΩ m
Mechanical properties
Elongation at break <44%
Izod impact strength 108 J m−1
Modulus of elasticity 186 GPa
Tensile strength 620–780 MPa
Physical properties
Density 8.5 g cm−3
Melting point 1420 °C
Thermal properties
Coefficient of thermal expansion 12.8×10−6 K−1 at 20–1000 °C
Maximum use temperature in air 1100 °C
Thermal conductivity 19 W m−1 K−1 at 23 °C

Chromel A

Chromel A is an alloy containing approximately 80% of nickel and 20% chromium (by weight). More precisely, Cr 20%, Fe 0.5%, Si 1%, Ni remainder [2] It is used for its excellent resistance to high-temperature corrosion and oxidation. It is also commonly called Nichrome 80-20 and used for electric heating elements.

Chromel C

Chromel C is an alloy containing 60% nickel, 16% chromium, and 24% iron. It is also commonly called Nichrome 60 and is used for heating elements, resistance windings, and hot wire cutters.

Chromel-R

Apollo 11 lunar EVA glove. The grey areas are Chromel-R

Chromel R has a composition of Cr 20%, Ni 80%.[2]

Chromel-R was also produced as a woven fabric of chromel wires. It was developed by Litton Industries for use by NASA in the Apollo program.[3] Patches of Chromel-R formed an outer layer of the spacesuit where abrasion resistance was needed.[4] These patches can be seen as silver-grey areas over the white Beta cloth of the main suit. The upper areas of the overshoes, the gloves[5] and patches beneath the life support backpack were of Chromel-R.

References

  1. Concept Alloys, Inc. Intellectual Property retrieved 12 April 2016
  2. 1 2 John P. Frick, ed. (2000). Woldman's Engineering Alloys. ASM International. p. 264. ISBN 9780871706911.
  3. Schneiderman, Deborah; Winton, Alexa Griffith (2016). Textile Technology and Design. Bloomsbury Publishing. p. 177. ISBN 9781474261968.
  4. "New Apollo is to have fireproof cabin materials and spacesuits". Popular Science. November 1967. p. 98.
  5. "Apollo Experience Report - Development of the Extra Vehicular Mobility Unit" (PDF), NASA Technical Note, NASA, p. 12, November 1975, NASA TN D-8093

External links


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