Thermal Conductivity and Stability of HfO2−Y2O3and La2Zr2O7Evaluated for 1650°C Thermal/Environmental Barrier Coating Applications [chapter]

Dongming Zhu, Narottam P. Bansal, Robert A. Miller
2012 Advances in Ceramic Matrix Composites IX  
HfO 2 -Y 2 O 3 and La 2 Zr 2 O 7 are candidate thermal and environmental barrier coating (T/EBC) materials for gas turbine ceramic matrix composite (CMC) combustor applications because of their relatively low thermal conductivity and high temperature capability. In this paper, thermal conductivity and high temperature stability of hot-pressed and plasma-sprayed specimens with representative partially-stabilized and fully-cubic HfO 2 -Y 2 O 3 compositions and La 2 Zr 2 O 7 were evaluated at
more » ... e evaluated at temperatures up to 1700 °C using a steady-state laser heat-flux technique. Sintering behavior of the plasma-sprayed coatings was determined by monitoring the thermal conductivity increases during a 20-hour test period at various temperatures. Durability and failure mechanisms of the HfO 2 -Y 2 O 3 and La 2 Zr 2 O 7 coatings on mullite/SiC hexoloy or SiC/SiC CMC substrates were investigated at 1650 °C under thermal gradient cyclic conditions. Coating design and testing issues for the 1650 °C thermal/environmental barrier coating applications are also discussed.
doi:10.1002/9781118406892.ch23 fatcat:xklxqhjglfe6xpxvgav5ocz6oe