Abstract
A transpiration cooling system for gas turbine applications has significant benefit for reducing the amount of cooling air and increasing cooling efficiency. In this paper, the porous ceramic coating using a plasma-spraying process, which can infiltrate a cooling gas and control the loss of coolant gas pressure, and the properties of the porous coating material fabricated in this study, such as permeability of the cooling gas, thermal conductivity and adhesion strength, are shown. The mixture of 8wt% yttria stabilized zirconia and polyester powders was employed as the coating, in order to deposit the porous ceramic coating onto the Ni-based super alloy substrate. The ceramic coating deposited with such mixed powder showed superior permeability for cooling gas and thereby to lead to considerable reduction of the substrate temperature based on the transpiration cooling mechanism. The adhesion strength of the porous ceramic coating was almost the same level as that of the ceramic coating utilized in current gas turbine components. The high-temperature exposure test revealed that the permeability of cooling gas did not change though a rigorous experience for a long period of up to 1000hours. It was also confirmed that the coating peeling damage did not occur after the thermal cycling test. It is concluded consequently that the transpiration cooling system proposed here for gas turbine could be achieved using the porous ceramic coating.
