Thermal insulation properties of YSZ coatings: Suspension Plasma Spraying (SPS) versus Electron Beam Physical Vapor Deposition (EB-PVD) and Atmospheric Plasma Spraying (APS)

Abstract

Improving efficiency of hot section components of aero engines such as turbine blades or nozzle guide vanes is critical for the aircraft industry. Over many years, the development of advanced Thermal Barrier Coatings (TBCs) has been a field of active research to achieve this purpose. Electron Beam Physical Vapor Deposition (EB-PVD) and Atmospheric Plasma Spraying (APS) processes are widely used to apply TBCs on metal substrates. High costs and rather high thermal conductivities of EB-PVD coatings, as well as low thermal lifetime of APS ones, are real drawbacks for next generations of turbine engines. In this study, Suspension Plasma Spraying (SPS) was assessed to improve TBC thermal properties. It was shown that the SPS process allows to perform columnar microstructure easily tunable in terms of both compaction of columnar structure and thermal conductivity. Thermal conductivities were in the 0.7–1.25W·m−1·K−1 range for SPS coatings while values of 0.9 and 1.5W·m−1·K−1 were measured for APS and EB-PVD coatings, respectively. The effect of heat conduction paths, which impact thermal diffusivity values, was highlighted for the columnar structure.