Anisotropic elastic properties of thermal spray coatings determined via resonant ultrasound spectroscopy

It is difficult to determine the elastic properties of thermal-sprayed ceramic and metallic coatings owing to the microstructural complexity, sample size and geometry, heterogeneity and availability of suitable techniques. Furthermore, the splat-based build-up of the coating results in transverse anisotropy in the elastic properties. This work reports on such anisotropic elastic properties of these coatings determined by resonant ultrasound spectroscopy. This approach, along with the analysis presented, enables the elastic properties to be determined for the first time as a function of direction and temperature, essential information for design. Coating systems investigated include plasma-sprayed yttria stabilized zirconia and nickel. An additional nickel coating deposited by the high-velocity oxygen-fuel process was also investigated and compared with the plasma-sprayed coating. Average Young’s moduli of the coatings were independently measured by indentation. The elastic properties determined enabled the coating microstructure–elastic property relationships to be described.