Comparison on Thermal Resistance Performance of YSZ and Rare-Earth GZ Multilayer Thermal Barrier Coating at 1250 ̊C Gas Turbine Combustor Liner

Abstract

Thermal barrier coating (TBC) is used to provide thermal resistance to hot section components in advanced gas turbines. By applying TBC, even at high temperature the durability and efficiency of the turbines can be improved. Yttria stabilized zirconia (YSZ) is the most selected material as the top coat due to its low thermal conductivity and relatively high thermal expansion coefficient. Gadolinium zirconate (GZ) was found to be an alternative material to YSZ due to their good phase stability at high temperature and lower thermal conductivity than the typical YSZ. Multi-layer coatings of GZ/YSZ are being researched in order to take advantage of these materials and improve the durability of the gas turbine combustor liners. This work focused on the study of multilayer (GZ/YSZ) TBC processed by air plasma spraying (APS) and compared with the currently used, standard single-layer of YSZ coating in terms of thermal resistance. The constant variables for both TBC systems are the usage of the bond coat (NiCrAlY), the deposition parameter used and the thickness for the whole TBC system. This thermal resistance test was conducted using a custom-made furnace which imitate almost similar of the GE Frame 9FA combustor liner operating conditions. It was found that than the single layer of YSZ system performed 12 % better rather than the multi-layered TBC system at 1250 ̊C.