New approach to low thermal conductivity of thermal barrier protection with improved mechanical integrity

Layered ceramic systems with designed stacks of dense and porous layers were investigated as alternative for thermal barrier protection system (TBPs). This approach gives the possibility to obtain low thermal conductivity with the impact protection of dense external layers whilst maintaining the relatively high mechanical properties. Different stacking configurations have been proposed utilizing in total a combination of up to 30 dense/porous layers. Porous layers were produced with two different nominal porosities 20 vol% and 40 vol%. For comparison uni-axial pressed samples with the same porosity level have been prepared. Thermal and mechanical characterization was performed on samples of tape cast (with different stacking designs) and uni-axial pressed fully stabilized zirconia TBPs. The layered fully stabilized zirconia (8YSZ) has 15-30 % lower thermal conductivity in comparison with the uni-axial pressed samples, nevertheless by the same Young`s modulus value. The results of the thermal and mechanical observation shows, that such an approach can be beneficial as an alternative for future thermal barrier protection systems.