Abstract:ZrO 2 (Y 2 O 3 )-based ceramics are widely used as biomaterials due to high fracture toughness, resulting from the tetragonal-monoclinic phase transformation in which the ceramic is submitted during crack propagation. In this context, studies involving the possibility of optimization of the tetragonal phase are important for the properties improvement of this ceramic. This study investigated the recovery of tetragonal phase from a previously transformed ZrO 2 (3 mol% Y 2 O 3 ) ceramic. Zirconia samples were si… Show more
“…As the specimens were sintered in a biphasic region (ZrO 2 -tetragonal+ZrO 2 -cubic) and both structures are remarkably difficult to be distinguished, all the refinements were conducted employing the methodology proposed in [15] The sintered specimens were ground and thoroughly polished using a sequence 9g6g1 µm diamond suspensions after sintering. After polishing, all specimens (discs) were heat-treated at 1250 °C/30 min to recover the tetragonal-ZrO 2 phase previously transformed to monoclinic ZrO 2 during polishing step [16]. The specimens were cleaned with acetone and then in isopropyl alcohol in an ultrasonic bath for 10 min.…”
The objectives of this study were to characterize and evaluate the physical and mechanical properties of an experimental zirconia for dental application and compare the biaxial flexural strength results with the finite element simulation (FEM). Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic samples were sintered at 1475 °C/2 h and characterized by X-ray diffraction, scanning electron microscopy, relative density, flexural strength using piston-on-three balls (P-3B) test and Young’s modulus. From the flexural strength results, numerical simulations were performed using Abaqus software. The complete model used 70216 elements, considering the components of the test. The results indicated full densification of sintered samples, ZrO2-tetragonal and ZrO2-cubic as crystalline phases, and average grain size of 0.6±0.2 μm. Mechanical characterization of sintered samples indicated Young’s modulus of 195±4 GPa, flexural strength of 1191±9 MPa and Weibull modulus m=16.3. FEM simulation indicated a flexural strength close to 1100 MPa, with a difference lower than 7% in relation to the experimental results. The results were compared associating the physical and mechanical properties of Y-TZP with its intrinsic phenomena such as tgm transformation and ferroelastic domain.
“…As the specimens were sintered in a biphasic region (ZrO 2 -tetragonal+ZrO 2 -cubic) and both structures are remarkably difficult to be distinguished, all the refinements were conducted employing the methodology proposed in [15] The sintered specimens were ground and thoroughly polished using a sequence 9g6g1 µm diamond suspensions after sintering. After polishing, all specimens (discs) were heat-treated at 1250 °C/30 min to recover the tetragonal-ZrO 2 phase previously transformed to monoclinic ZrO 2 during polishing step [16]. The specimens were cleaned with acetone and then in isopropyl alcohol in an ultrasonic bath for 10 min.…”
The objectives of this study were to characterize and evaluate the physical and mechanical properties of an experimental zirconia for dental application and compare the biaxial flexural strength results with the finite element simulation (FEM). Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic samples were sintered at 1475 °C/2 h and characterized by X-ray diffraction, scanning electron microscopy, relative density, flexural strength using piston-on-three balls (P-3B) test and Young’s modulus. From the flexural strength results, numerical simulations were performed using Abaqus software. The complete model used 70216 elements, considering the components of the test. The results indicated full densification of sintered samples, ZrO2-tetragonal and ZrO2-cubic as crystalline phases, and average grain size of 0.6±0.2 μm. Mechanical characterization of sintered samples indicated Young’s modulus of 195±4 GPa, flexural strength of 1191±9 MPa and Weibull modulus m=16.3. FEM simulation indicated a flexural strength close to 1100 MPa, with a difference lower than 7% in relation to the experimental results. The results were compared associating the physical and mechanical properties of Y-TZP with its intrinsic phenomena such as tgm transformation and ferroelastic domain.
“…Porém, a transformação de fase tetragonal para monoclínica (t-ZrO2 -> m-ZrO2) envolve uma considerável expansão volumétrica (~4%) que é fortemente anisotrópica, com mudanças abruptas nos parâmetros de rede, provocando grandes variações na estrutura cristalina. (Cain, 1990), (Samis, 1995), (Rendtorff, 2009), (Umeri, 2010), (Gallino, Valentin, & Pacchioni, 2011), (Simba, et al, 2016) Uma liga de zircônia com vários tipos de solutos como MgO, CaO, Y2O3 ou CeO2, dependendo do seu tratamento térmico e da sua composição, pode apresentar a estabilidade de polimorfismo afetada, resultando em materiais multifásicos. A ocorrência de uma fase ou fases com simetria ortorrômbica em ligas ZrO2 e ZrO puras foi relatada em algumas ocasiões.…”
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