Evaluation of Delamination Life of 8mass%Y2O3·ZrO2/NiCoCrAlY Thermal Barrier Coating under Creep Deformation
Masahiko KATO, Keijiro NAKASA, Baohua ZHAO and Gou TANIGUCHI
Abstract:Thermal barrier coating(TBC) was applied to Ni based superalloy specimens, where bond coat was NiCoCrAlY deposited by high velocity oxygen fuel(HVOF) spraying and top coat was 8mass% yittria stabilized zirconia(YSZ) by atmospheric plasma spraying. The creep tests of the specimens were carried out at 1273K, 1373K and 1423K by three-point bending until the delamination of coating. The results showed that the creep strain increased with increasing loading time and heating temperature, and the strain at delamination decreased both with increasing time and decreasing temperature. An equation to evaluate the delamination life of TBC was introduced by combining the damage of interface due to heat cycle, holding time and creep deformation using the strain parallel to interface. The predicted delamination life coincided relatively well with experimental one. Key Words:Thermal barrier coating, Creep strain, High temperature, Oxide layer, Delamination, Life prediction