International Journal of Thermophysics

, Volume 29, Issue 1, pp 222–230 | Cite as

Optimizing Heat Treatment of Gas Turbine Blades with a Co–C Fixed Point for Improved In-service Thermocouples

  • J. V. PearceEmail author
  • G. Machin
  • T. Ford
  • S. Wardle


Improvement of energy efficiency of jet aircraft is achieved by operating gas turbine engines at higher temperatures. To facilitate this, gas turbine engine manufacturers are continuously developing new alloys for hot-zone turbine blades that will withstand the increased in-service temperatures. A critical part of the manufacture of these blades is heat treatment to ensure that they attain the necessary metallurgical characteristics. Current heat-treatment temperature-control requirements are at the limit of what is achievable with conventional thermocouple calibrations. A project that will allow thermocouple manufacturer CCPI Europe Ltd. to realize uncertainties of ± 1°C, or better, in the calibration of its noble metal thermocouples is described. This will be realized through implementing a Co–C eutectic fixed point in CCPI’s calibration chain. As this melts at 1,324°C, very close to the heat-treatment temperatures required, low uncertainties will be obtained. This should yield an increase in effectiveness of the heat-treatment process performed by Bodycote Heat Treatments Ltd., allowing them to respond effectively to the increasingly stringent demands of engine manufacturers. Outside the current project, there is a strong requirement by industry for lower uncertainties at and above 1,300°C. Successful implementation of the current fixed point in an industrial setting is likely to result in rapid take-up by other companies, probably through the supply of ultra-low uncertainty thermocouples, looking to improve their high-temperature processes.


Aerospace Heat transfer High temperatures Melting Thermocouples 


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  1. 1.
    Yamada, Y., Sakate, H., Sakuma, F., Ono, A.: Metrologia 36, 207 (1999)CrossRefADSGoogle Scholar
  2. 2.
    Woolliams, E.R., Machin, G., Lowe, D.H., Winkler, R.: Metrologia 43, R11 (2006)CrossRefADSGoogle Scholar
  3. 3.
    Yamada, Y.: MAPAN 20, 183 (2005)Google Scholar
  4. 4.
    Edler, F., Baratto, A.C.: Metrologia 42, 201 (2005)CrossRefADSGoogle Scholar
  5. 5.
    M. Sadli, J. Fischer, Y. Yamada, V.I. Sapritsky, D. Lowe, G. Machin, in Proceedings of TEMPMEKO 2004, 9th International Symposium on Temperature and Thermal Measurements in Industry and Science, ed. by D. Zvizdić, L.G. Bermanec, T. Veliki, T. Stašić (FSB/LPM, Zagreb, Croatia, 2004), pp. 341–347Google Scholar
  6. 6.
    R. Morice, F. Edler, J. Pearce, G. Machin, J. Fischer, J.R. Filtz, in Proceedings of TEMPMEKO 2007, Int. J. Thermophys., doi:  10.1007/s10765-007-0356-y
  7. 7.
    Pearce, J.V.: Metrologia 44, L1 (2007)CrossRefADSGoogle Scholar
  8. 8.
    Anhalt, K., Hartmann, J., Lowe, D., Machin, G., Sadli, M., Yamada, Y.: Metrologia 43, S78 (2006)CrossRefADSGoogle Scholar
  9. 9.
    F. Edler, R. Morice, J. Pearce, in Proceedings of TEMPMEKO 2007, Int. J. Thermophys., doi:  10.1007/s10765-007-0353-1

Copyright information

© GovernmentEmployee: National Physical Laboratory, UK 2008

Authors and Affiliations

  1. 1.National Physical LaboratoryTeddingtonUK
  2. 2.CCPI Europe, Units 3, 4 & 5KillamarshUK
  3. 3.Bodycote Heat Treatments Ltd.DerbyUK

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