CCS and Power Systems
Advanced Energy Systems - Hydrogen Turbines
Degradation of TBC Systems in Environments Relevant to Advanced Gas Turbines for IGCC Systems
Performer: University of Pittsburgh
Project No: FE0007271
Free-standing YSZ coupons reacted with commercial fly ash. A thin reaction layer formed at 1200 °C, while the ash melted and severely degraded the YSZ at 1300 °C.
YSZ reacted with a synthetic ash at 1100 °C for 72 hours showing a continuous reaction layer. Synthetic ash mixtures with lower amounts of CaO did not form this reaction product, showing that there is a minimum CaO activity necessary in the ash to react with the YSZ.
NiCoCrAlY alloys after 50 hours exposure to class C fly ash in CO2-H2O at 1100 °C. Alloy degradation is mitigated when increasing the β phase fraction.
YSZ reacted with synthetic ash (SA) with and without additions of K2SO4 and FeS. The reaction product formed with only synthetic ash does not infiltrate the cracks in the YSZ. The degradation is more aggressive with the additives: the reaction product is thicker and the infiltration is more significant.
Ni-19Co-15Cr-24Al-0.3Y (atomic %) after 50 hours exposure to class C fly ash in CO2-H2O at 1100 oC. Excessive doping caused extensive alloy degradation.
NiCoCrAlY alloys after 50 hours exposure to CaO in air at 1100 °C. Reaction of CaO with the Cr-rich γ-phase to form a calcium chromate causes extensive alloy degradation.
Role of phase distribution in CaO-induced degradation of β-γ NiCoCrAlY alloys.