Deposition rate dependent phase/mechanical property evolution in zirconia and ceria-zirconia thin film by EB-PVD technique

Abstract

Pure zirconia (ZrO2) and ceria (16 mol%) stabilized zirconia (CeSZr) thin films were prepared by electron beam physical vapor deposition with varying deposition rates (1, 4 and 8 Å/s) in order to correlate the phase changes to the mechanical property. X-ray diffraction and Raman spectra results indicate the presence of mixed monoclinic and tetragonal phases in ZrO2 film, but tetragonal phase dominated at lower deposition rate. However, irrespective of the deposition rate, cerium addition to ZrO2 resulted in complete stabilization of tetragonal phase. Depending on the presence of dual (ZrO2) or single (CeSZr) phase, either surface cracks or well-connected grain structure was observed in SEM, respectively. Thus, CeSZr film showed a four-fold increase in hardness in comparison to ZrO2, which can be attributed to the complete stabilization of tetragonal phase that hinders the crack propagation along the grain. Plastic deformation of CeSZr film was found to be 1.80 × 10−2 GPa, which is about ∼55% higher as compared to pure ZrO2 film (8.04 × 10−3 GPa). Thus, the development of CeSZr coating may lead to better surface protection of many components.