Non-contact sensing of TBC/BC interface temperature in a thermal gradient

• Published in: Surface & coatings technology 2006-12, Vol.201 (7), p.3937-3941
• Main Authors: Gentleman, M.M., Eldridge, J.I., Zhu, D.M., Murphy, K.S., Clarke, D.R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Luminescence; Metals. Metallurgy; Nonmetallic coatings; Production techniques; Sensors; Surface treatment; Thermal barrier coatings; Thermal gradient
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2006.08.102

Luminescence lifetimes of rare-earth ions in yttria-stabilized zirconia have been shown to exhibit temperature sensitivity from 500–1150 °C [Gentleman, M.M. and Clarke, D.R. (2005) Surface and Coatings Technology 200, 1264; Gentleman, M.M. and Clarke, D.R. (2004) Surface and Coatings Technology 188–189, 93.]. These doped zirconias can be deposited along with standard thermal barrier coatings to create thin temperature sensing layers within the coating. Of particular interest is the temperature at the coating/bond coat interface as the oxidation life of a TBC system is exponentially dependent on this temperature. In this study, thin (∼ 10 μm) layers of europia-doped yttria-stabilized zirconia were deposited by EB-PVD onto bond-coated CMSX-4 superalloy buttons to achieve sensor layers located next to the TBC/BC interface. These coatings were then used to measure the interface temperature in a thermal gradient. Combined with pyrometric measurements of the coating-surface temperature and metal-surface temperature, the thermal conductivity of the coating (1.5 W/mK) and heat flux (∼ 1 MW/m 2) in the tests were calculated.