| Texto completo | |
| Autor(es): |
Piza, Mariana M. T.
;
Bergamo, Edmara T. P.
;
Campos, Tiago M. B.
;
Carvalho, Laura F.
;
Goulart, Celso A.
;
Gutierres, Eliezer
;
Lopes, Adolfo C. O.
;
Jalkh, Ernesto B. Benalcazar
;
Bonfante, Estevam A.
Número total de Autores: 9
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Dental Materials; v. 39, n. 11, p. 10-pg., 2023-10-14. |
| Resumo | |
Objectives: To process an alumina-toughened zirconia (ATZ) nanocomposite and to characterize its crystalline phases, microstructure, residual stress, mechanical and optical properties before and after two different artificial aging methodologies. Methods: Disc-shaped specimens were obtained through uniaxial pressing of a commercial ATZ powder comprised of 80%ZrO2 / 20%Al2O3, with a particle size of 50 nm and 150 nm, respectively. Sintering was performed at 1500 degrees C for 2 h. Groups were established according to the aging protocol as immediate (ATZ-I) and aged either in autoclave (ATZ-A) or hydrothermal reactor (ATZ-R) at 134 degrees C for 20 h at 2.2 bar. Crystalline phases and microstructure were assessed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Residual stress was evaluated by Raman spectroscopy. Contrast Ratio (CR) and Translucency Parameter (TP) were calculated to characterize optical properties. Mechanical properties were analyzed through Vickers microhardness, fracture toughness, and biaxial flexural strength test.Results: XRD spectra of both aging protocols revealed the presence of monoclinic zirconia (20-31%), where higher phase transformation was observed after aging in hydrothermal reactor. Optical properties evaluation demonstrated high opacity (CR: 0.99) and masking ability (TP: 0.26), with no significant differences after aging. Raman spectroscopy evidenced the presence of residual compressive stresses in the aged groups, being significantly higher for ATZ-R (-215.2 MPa). As-sintered specimens revealed hardness of-12.3 GPa and fracture toughness of-1.9 MPa.m1/2. Characteristic strength was 740 MPa for ATZ-I, 804 MPa for ATZ-A, and 879 MPa for ATZ-R, with significant differences between groups. Weibull modulus ranged from 16.5 to 18.8. All groups demonstrated high reliability up to 500 MPa stress missions (99-100%), with no significant differences after aging.Significance: The experimental ATZ nanocomposite presented high opacity and a high Weibull modulus. While aging created internal compressive stress responsible for an increase in characteristic strength, the nano-composite was susceptible to hydrothermal degradation. Further studies are required to evaluate its degradation kinetics at low temperatures. (AU) | |
| Processo FAPESP: | 12/19078-7 - Desenvolvimento e processamento de compósito de Al2O3-ZrO2 para próteses monolíticas CAD/CAM: efeito do envelhecimento na resistência à flexão biaxial |
| Beneficiário: | Estevam Augusto Bonfante |
| Modalidade de apoio: | Auxílio à Pesquisa - Jovens Pesquisadores |
| Processo FAPESP: | 19/14798-0 - Desenvolvimento de blocos pré sinterizados de compósito ZTA - 80%Al2O3/20%ZrO2 para fresagem em sistema CAD/CAM |
| Beneficiário: | Adolfo Coelho de Oliveira Lopes |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |
| Processo FAPESP: | 16/18818-8 - EMU concedido no processo 2012/19078-7: ElectroPuls E3000 Linear-Torsion All-Electric dynamic test instrument package |
| Beneficiário: | Estevam Augusto Bonfante |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Equipamentos Multiusuários |
| Processo FAPESP: | 21/08018-2 - Caracterização nanomecânica de compósitos ZTA e ATZ infiltrados por vidro |
| Beneficiário: | Edmara Tatiely Pedroso Bergamo |
| Modalidade de apoio: | Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado |
| Processo FAPESP: | 20/12874-9 - Infiltração gradada por vidro em um compósito experimental à base de whiskers de alumina e zircônia: desenvolvimento, caracterização microestrutural e das propriedades ópticas e mecânicas |
| Beneficiário: | Tiago Moreira Bastos Campos |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 19/08693-1 - Compósitos experimentais à base de alumina e zircônia infiltrados por vidro: caracterização microestrutural e das propriedades ópticas e mecânicas. |
| Beneficiário: | Edmara Tatiely Pedroso Bergamo |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 22/07157-1 - Caracterização física e mecânica de um sistema multicamadas utilizando zircônia reciclada |
| Beneficiário: | Ernesto Byron Benalcazar Jalkh |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |