Biaxial flexural strength, roughness and hardness of monolithic zirconias: effect of silica infiltration by sol-gel method and physiological wear simulation

Author(s)

Larissa Marcia Martins Alves

• Document type: Master's Dissertation
• Press: São José dos Campos. 2017-01-26.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Ciência e Tecnologia. São José dos Campos
• Defense date: 2016-12-20
• Advisor: Renata Marques de Melo Marinho; Tiago Moreira Bastos Campos

Abstract

This study evaluated the mechanical properties (biaxial flexural strength and hardness) and surface properties (roughness) of infiltrated, glazed or polished monolithic zirconia. 198 zirconia discs were prepared (14 mm diameter, 1,2 mm thickness). The specimens were polished with SiC abrasive paper #1200, and then specimens were divided into three main groups (n=66). In the first, the discs were infiltrated with silica, in the second were glazed and and in third were polished with abrasive rubbers. Thereon, were divided into two subgroups (n=33), in which only one group of each treatment was subjected to wear with steatite, in order to simulate the physiological wear. The specimens were then subjected to roughness analysis, hardness and biaxial bending test (ISO 6872) immersed in water. The groups were evaluated by x-ray diffraction (XRD). The strength values (MPa) were ranked and subjected to Weibull analysis to calculate the Weibull modulus and characteristic strength of the material (CI 95%). The samples were also analyzed by SEM to visualize the wear. In the XRD, it was showed that the treatments did not induce phase transformation as well as wear, however the polishing induced the formation of a compressed cubic phase on the surface. SEM showed the surfaces of the samples with grooves formation on polished, zirconium silicate on infiltrated and irregularities on glazed. It was also possible to verify the removal of surface treatment after simulated wear. The glaze showed higher roughness amd hardness, with a significant difference compared to the other treatments, when there was no wear. In groups with wear there was no significant difference. The results of the bending test, the group with the highest average was polished without wear and after the Weibull analysis, there was no significant difference among them. (AU)

• FAPESP's process: 15/11405-7 - Biaxial flexural strenght, roughness and hardness of monolithic zirconias: effect of silica infiltration by sol-gel method and physiological wear simulation
• Grantee: Larissa Marcia Martins Alves
• Support Opportunities: Scholarships in Brazil - Master