Emissivity measurements for YSZ thermal barrier coating at high temperatures using a 1.6-μm single-wavelength pyrometer

Sami D. Alaruri, MEMBER SPIE Lisa Bianchini Andrew J. Brewington Allison Engine Company Rolls Royce Aerospace Group P.O. Box 420, M/S W03A Indianapolis, Indiana 46206-0420 Abstract. A method that employs an integrating sphere and a singlewavelength (1.6-mm) pyrometer to measure the spectral effective emissivities of YSZ thermal barrier coatings in the temperature range (;650 to 1050°C) is described. The effective spectral emissivities for two YSZ samples are measured as a function of the heat cycle duration. An increase in the emissivity of the YSZ samples is observed after the first heat cycle. Such an increase is attributed to the diffusion of aluminum and aluminum oxide from the bond-coat into the YSZ layer. The average effective spectral emissivity measured for YSZ after the first heat cycle was 0.72960.013. © 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)03002-5]