Effect of thermal exposure on stress distribution in TGO layer of EB-PVD TBC

The stress distributions in thermally grown oxide (TGO) layer of electron beam enhanced physical vapor deposited thermal barrier coating (EB-PVD TBC) before and after thermal exposure are measured by photo-stimulated luminescence spectrum. It is found that the stress in the TGO layer in original state is an order of ∼3 GPa. It increases from 3.0-3.9 GPa with the increase of heat exposure time from 0-100 h. The stress distribution in the direction of thickness in the TGO layer is not uniform. The stress near ceramic top coat is smaller than that close to metal bond coat. The stress at thickness imperfections in the TGO near the bond coat is smaller than that in the regular TGO