|
6356 |
|
Thursday, June 11, 2020, Hall D 9:00 AM Power Generation - Industrial Gas Turbines |
|
Industrial TBC systems under CMAS attack: Different YSZ behavior in chemical resistance |
|
Omar Ligabue* / Lincotek Surface Solutions S.p.A., Italy Simone Bursich / Turbocoating S.p.A., Italy Nelso Antolotti/ Turbocoating S.p.A., Italy Stefania Morelli/ 2Department of Engineering Enzo Ferrari , University of Modena and Reggio Emilia, Italy Giovanni Bolelli/ 2Department of Engineering Enzo Ferrari , University of Modena and Reggio Emilia, Itlay Luca Lusvarghi/ 2Department of Engineering Enzo Ferrari , University of Modena and Reggio Emilia, Italy |
|
The thermochemical reaction between CMAS (calcium magnesium aluminum silicate) and ceramic top coat, based on YSZ (yttria-partially stabilized zirconia), represents one of the major reasons for TBC failure in both IGT (industrial gas turbine) and aviation engine components. This is mainly due to chemical dissolution and de-stabilization of the YSZ ceramic due to the interaction and attack of these silicates, deposited onto hot-section components and then molten during service. In this study the performance of different TBC industrial systems has been evaluated in order to understand the resistance to CMAS attack. Systems with standard porosity and DVC (dense-vertically cracked) microstructure were prepared via APS, while a columnar top coat was obtained by SPS (suspension plasma spray). CMAS attack was simulated in an oven, keeping the silicate stoichiometry and thermal cycle conditions constant. The characterization of the samples after CMAS attack, via SEM-EDX, Raman spectroscopy and XRD, shows that chemical reaction occurs mainly along YSZ grain boundaries and it is promoted by coating porosity. Chemical purity also played a role because the attack seems to be slower and less severe in samples obtained using a higher YSZ purity feedstock. TBC systems were ranked in terms of CMAS attack resistance. |