Burner rig testing of "herringbone" EB-PVD Thermal Barrier Coatings

In order to lower the thermal conductivity of Electron Beam-Physical Vapour Deposited Thermal Barrier Coatings (EB-PVD TBCs), so-called " herringbone " TBCs with a zigzag or wavy column structure have been developed. This structure can result in more than 25 % reduction in thermal conductivity compared to a straight column TBC. This paper focuses on burner rig tests which were done to assess the service life of herringbone TBCs. Burner rig tests at 1135 °C and with a cycle length of 5 minutes showed that the number of cycles to failure of the herringbone TBCs was comparable to but lower than that of reference straight column TBCs. Furthermore, the symmetric zigzag TBCs showed erosion at the flame-heated side. It is concluded that though the new herringbone TBCs show promising thermal properties, the production process must be optimised to improve the life and flame erosion resistance.