Original paper(Vol.48 No.7 pp.740)

Abstract:Thermal barrier coatings (TBCs) had been already applied to hot section parts of gas turbines, such as a bucket and a combustor. It is thought that TBCs are in dispensable for the bas turbines in campany with cooling technologies. Nowadays, it is desired the higher durability to TBCs with increasing the combustion temperature. The object of this study is to clearify the sintering behavior under the condition of gradient temperature for the plasma sprayed zirconia TBC in air atmosphere. On the assumption based on experimental results that the linear shrinkage of zirconia coating followed a 2/5 power time law and an Arrhenius type temperature dependence of sintering rate constants, thermal stress behavior due to sintering under the gradient temperature was made clear by the simulation analysis. There was a tendency that the tension stress at zirconia coating layer increased with increasing the combustion temperature and heating time. The cracking conditions of zirconia coating was estimated by paying attention to the shrinkage stress and residual stress due to the difference of thermal expansion.

Key Words:Thermal barrier coating, Zirconia, Air plasma spray, MCrAlY bond coating, Sintering, Shrinkage stress, Residual stress, TBC cracking