Chromel

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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[edit]

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[edit]

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[edit]

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[edit]

  1. ^ Concept Alloys, Inc. Intellectual Property retrieved 12 April 2016
  2. ^ a b 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[edit]