Development of deposition beam current dependent microstructure and nanomechanical properties in ZrO2-8wt%Y2O3 thermal barrier coatings produced by electron beam-physical vapor deposition technique

Abstract 8 wt% yttria stabilized zirconia (8YSZ) coatings have been produced by changing the beam currents of electron beam-physical vapor deposition. The phase composition, microstructure, roughness, nanomechanical properties and residual stress were characterized and analyzed. The as-deposited 8YSZ coating was mainly composed of the metastable tetragonal phase. The enhancement of deposition beam current caused larger crystallite sizes and root mean square roughness, which confirmed by microscopic observations and atomic force microscopy technique. The nanomechanical properties were evaluated by an instrumented nanoindentation test. It was found that Young's modulus and hardness increase with the improvement of deposition beam current, which is due to the lower porosity. The thermal residual stresses generated in the deposition process was measured by two-dimension X-ray diffraction using sin2ψ technique. The measurement result indicated that residual stresses were dependent on the coating process.