Synthesis of an ATZ nanocomposite (80%ZrO2-20%Al2O3) and microstructural, optical and survival characterization before and after aging

• Grant number: 20/16500-6
• Support type: Scholarships in Brazil - Master
• Effective date (Start): October 01, 2021
• Effective date (End): March 31, 2022
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal researcher: Estevam Augusto Bonfante
• Grantee: Mariana Miranda de Toledo Piza
• Home Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Associated research grant: 12/19078-7 - Development and processing of Al2O3-ZrO2 translucent composite for CAD/CAM monolithic prostheses: the effect of aging on biaxial flexural strength, AP.JP

Abstract

Polycrystalline Tetragonal Zirconia stabilized by 3 mol% of Yttria (3Y-TZP) is a promising material in dentistry, however its hydrothermal instability has motivated innovations in the area. It is known that 3Y-TZP can present degradation at low temperatures (DBT), resulting in changes in its properties. Thus, this study seeks to continue the FAPESP project 2018/19094-9 inserted in the aid Young Researcher 2012/19078-7, in the synthesis line of ATZ (80% ZrO2 -20% Al2O3, Alumina-Toughened Zirconia) having as differential the synthesis of an ATZ from nanometric powders, where microstructural, optical and survival characterization will be carried out, before and after being subjected to aging. The objective is to develop a composite with increased mechanical properties and less susceptibility to DBT when compared to that described in the proposal FAPESP 2018/19094-9. 120 specimens of ATZ nano will be prepared, all in disk format and final dimensions of 12mm in diameter and 1mm in thickness, via uniaxial and isostatic pressing. The samples will be divided into 3 groups: ATZi (immediate), ATZea (aged in autoclave), ATZer (aged in hydrothermal reactor). After sintered and polished, the groups ATZea and ATZer, will be submitted to the aging protocol for 25h, at 134ºC and 2.2 bars, simulating the effects of DBT. The optical properties will be evaluated (n=10/group) in a spectrophotometer to obtain values of contrast ratio and translucency parameter. The biaxial flexural strength test (ISO 6872:2015) (n=30/group) and fractographic analysis will be performed to calculate the probability of survival, Weibull modulus and characteristic strength. The crystalline phases will be observed by X-ray diffraction (XRD) (n=5/group).