Evaluation of Thermal Insulation Performance of EB-PVD YSZ Thermal Barrier Coatings by Phosphorescence Lifetime Online Measurement

Abstract

Precise measurement of the thermal insulation performance of thermal barrier coatings (TBCs) under the thermal gradient environment is important for the design and development of TBCs. A phosphorescent sensor TBC which contains an Eu doped yttria-stabilized zirconia (YSZ:Eu) surface layer, a YSZ intermediate layer, and a YSZ:Dy bottom layer, is designed and prepared by electron beam physical vapor deposition (EB-PVD). Based on the thermal quenching characteristics of phosphorescence signal, the surface temperature of the YSZ coating and the interface temperature of the bond-coat/YSZ layer are measured online in a temperature gradient environment, and the real thermal insulation effect of the EB-PVD YSZ thermal barrier coating is evaluated. The results show that the EB-PVD YSZ coating with a thickness of 113 μm can achieve an average temperature decrease of 66.5 ℃. The average thermal conductivity of the coating is (0.87±0.15) W/(m·K) in the temperature range between 400 and 700 ℃, which is slightly lower than the value (0.95±0.02) W/(m·K) obtained by using the traditional laser flash method. The above results validate the reliability of online phosphorescence temperature measurement technique, and provide an effective method to monitor the thermal insulation effect of TBCs in real time.

Keywords

• thermal barrier coatings (tbcs)
• phosphorescence online temperature measurement
• thermal insulation
• thermal conductivity
• electron beam physical vapor deposition (eb-pvd)