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

Abstract

The determination of elastic properties of plasma-sprayed ceramic and metallic coatings is difficult due to their complex microstructure, which involves a myriad array of pores, interfaces and other defects. Furthermore, the splat-based build-up of the coating results in transverse anisotropy in the elastic properties. In this paper, we report on the anisotropic elastic properties of these coatings determined by resonant ultrasound spectroscopy (RUS). This approach along with the analysis presented enables, for the first time, the determination of elastic properties as a function of direction and temperature for these complex systems with concomitant implications for design. The coating systems investigated included plasma-sprayed yttria-stabilized zirconia (YSZ) and nickel. An additional nickel coating deposited by high-velocity oxygen-fuel process was investigated and its elastic properties were compared to those of plasma-sprayed nickel. Average Young’s moduli of the coatings were independently measured by using the instrumented indentation method. The elastic properties determined from the RUS and indentation methodologies allowed description of the microstructure–elastic property relationships in the coatings.