Analysis of Residual Stress and Damage Durability with Thermal Fatigue Behavior in Thermal Barrier Coatings

摘要

Static thermal fatigue tests for thermal barrier coatings (TBCs) were conducted to observe effects of temperature and holding time on its mechanical properties, hardness and modulus, and damage durability. For which three TBCs samples with different thickness in bonding layer (0.08, 0.14, and 0.28 mm) were prepared using an air plasma spraying (APS) method. Temperature of 950 and 1100℃ and holding time of 10 and 100 hr were selected for the thermal fatigue tests. The TBCs with thin bonding layer (0.08 mm) maintain sound condition for all the thermal fatigue tests, even showing an evidence of cracking at the interface between coating and bonding layers. However, the TBCs with intermediate (0.14 mm) and thick (0.28 mm) bonding layers show delamination at interface and fracture of coating layer after the thermal fatigue tests at 1100℃ for 100 hr. Thermal growth oxide (TGO) layer is created at the interface between coating and bonding layers in all the TBCs after the thermal fatigue tests, and the TGO layer thickness is mainly affected by temperature. Modulus and hardness of coating layer are increased with an increase of temperature in the thermal fatigue tests, due to the re-sintering of coating layer during the thermal fatigue tests. Effects of bonding layer thickness and thermal fatigue condition on mechanical properties, residual stresses, damage durability of the TBCs are discussed extensively.