Infiltration graded by glass in an experimental composite based on whiskers of alumina and zircônia: development, microstructural characterization and optical and mechanical properties

Abstract

Glass infiltration in polycrystalline ceramic systems has shown to improve optical and mechanical properties, as well as adhesion by silanization methods. Although such advantages have already been proven for zirconia based systems, these material are susceptible to Low Temperature Degradation (LTD), which was the rationale behind the Young Investigator proposal #2012/19078-7 that motivated the development of zirconia-alumina composites (Zirconia-Toughened Alumina-ZTA and Alumina-Toughened Zirconia-ATZ). Preliminary data reported to FAPESP and already published in the literature have demonstrated the successful development of ceramic composites resistant to LTD with unaltered optical and mechanical properties. Thus, this project aims to innovate on two ways: 1) the development of a zirconia-based composite with the addition of alumina whiskers with a high potential to increase the mechanical properties and expand the use of the already developed composites of the Young Investigator grant, and; 2) the development of a compatible bioglasses for the gradual infiltration of this composite, aiming an additional gain in the mechanical properties and especially in the optical and adhesion properties. The material will be synthesized in a proportion of 10% Al2O3-90% ZrO2, with alumina in the form of whiskers and conventional zirconia, tetragonal yttria-stabilized (Y-TZP). After sintering, the materials will be characterized by Energy-Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FT-IR) and X-Ray Diffraction (XRD). The density will be estimated, and the optical properties will be evaluated in a spectrophotometer. Hardness and fracture toughness will be calculated using Vickers indentation and gradual variation in the modulus of elasticity by nanoindentation. The biaxial flexural strength test will be performed to calculate the probability of survival, Weibull modulus and characteristic strength. (AU)