COMPARISON OF THERMAL SHOCK BEHAVIOR OF 7YSZ, 15YSZ AND SYSZ THERMAL BARRIER COATINGS PRODUCED BY APS METHOD

Nanostructured scandia, yttria doped zirconia (SYSZ), 7wt. % yttria stabilized zirconia (7YSZ) and 15YSZ thermal barrier coatings (TBCs) were produced by plasma spraying on nickel-based superalloy substrates with NiCrAlY as the bond coat. The thermal shock behavior of the three as-sprayed TBCs at 1000 °C was investigated. The results indicated that the thermal cycling lifetime of SYSZ and 7YSZ TBCs was longer than the 15YSZ TBCs due to the lower thermal mismatch stress between the ceramic layer and the metallic layer at high temperature and higher amount of tetragonal phase.