Journal of the American Ceramic Society, Vol.98, No.12, 3639-3642, 2015
Microtexture Analysis of the Alumina Scale in Thermal Barrier Coatings
Transmission electron microscopy-based grain orientation mapping method was employed to investigate the microtexture of the alumina scale formed in commercial thermal barrier coatings (TBCs) with two standard types of Pt-enriched bond coats. Reliable orientation/phase maps with a spatial resolution down to 2 nm were acquired on the alumina grains. It was observed that the alumina scale on the Pt-aluminide beta-phase bond coat has a stronger c-axis texture normal to the bond coat surface, in comparison with that on the Pt-diffused gamma/gamma'-phase bond coat. The microtexture of the alumina scale could affect its effective coefficient of thermal expansion, which is a contributor to the severity of the bond coat rumpling mechanism of TBCs failure.