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: | |
|---|---|
| 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
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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
- ^ Concept Alloys, Inc. Intellectual Property retrieved 12 April 2016
- ^ a b John P. Frick, ed. (2000). Woldman's Engineering Alloys. ASM International. p. 264. ISBN 9780871706911.
- ^ Schneiderman, Deborah; Winton, Alexa Griffith (2016). Textile Technology and Design. Bloomsbury Publishing. p. 177. ISBN 9781474261968.
- ^ "New Apollo is to have fireproof cabin materials and spacesuits". Popular Science. November 1967. p. 98.
- ^ "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
- Materials properties of thermocouple wires sold by Omega Engineering, Inc.
- Technical information on alloys at Electrovek-Steel Ltd.
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