Durability of YSZ coated Ti ₂ AlC in 1300°C high velocity burner rig tests

Abstract

Abstract A thermal barrier coating (TBC) system survived 500 hours in aggressive, 1300°C burner rig testing. The yttria‐stabilized zirconia (7YSZ) TBC was plasma sprayed on an oxidation‐resistant Ti 2 AlC‐type MAX phase and tested in a jet fuel burner at 100 m/s, using 5 hours cycles. No coating spallation or surface recession was observed; Al 2 O 3 ‐scale growth produced a slight 2.4 mg/cm 2 mass gain. The coating surface exhibited craze‐cracked colonies of [111] flourite textured columns, with no visible moisture attack. The 20 μm alumina scale remained intact under the YSZ face, about twice that producing failure for TBC/superalloy systems. TiO 2 nodules, initially formed on the uncoated backside, were removed, and Al 2 O 3 was etched through volatile hydroxides formed in water vapor (~10%). Overall, the test indicated exceptional stability of the YSZ/Al 2 O 3 /Ti 2 AlC system under turbine conditions due in large part to close thermal expansion matching.