Physical and mechanical characterization of a bilayered zirconia system: influence of hydrothermal aging

Abstract

A strategy to further improve the mechanical properties of ultra-translucent zirconia systems (Y-PSZ) has been recently proposed through the development of layered systems. However, multilayered zirconia systems have shown a significant reduction in the strength relative to the isolated counterparts, which was associated with the presence of defects at the interface. Hence, the objective of the present study will be the study of different zirconia powders and processing routes for bilayered zirconia systems, and to investigate their optical and mechanical performance when subjected to hydrothermal aging. Commercial zirconia powders (3Y-TZP, 4Y-PSZ, and 5Y-PSZ) will be acquired. Bilayered zirconia discs will be processed via successive uniaxial pressing, where the first layer will consist of a 3Y-TZP or a 4Y-PSZ powder and the second layers of a 5Y-PSZ. After sintering and polishing, half of the specimens will be aged and characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD) to investigate microstructure and crystalline content, respectively. The density will be determined using Archimedes principle. Optical properties will be evaluated in a spectrophotometer using reflectance tests. The hardness will be calculated using Vickers indentation test. The biaxial flexural strength test will be conducted to determine the probability of survival, Weibull modulus and characteristic strength. (AU)