Mechanical properties and resistance to hydrothermal aging of ceria- and yttria-doped tetragonal zirconia ceramics

The microwave sintered zirconia ceramics with 0, 1, 3, and 5 wt% TiO2addition at a low sintering temperature of 1300°C and a short holding time of 1 hour were investigated. Effect of contents of TiO2addition on microstructure and mechanical properties of microwave sintered zirconia bioceramics was reported. In the sintered samples, the main phase is monoclinic zirconia (m-ZrO2) phase and minor phase is tetragonal zirconia (t-ZrO2) phase. The grain sizes increased with increasing the TiO2contents under the sintering temperature of 1300°C. Although the TiO2phase was not detected in the XRD pattern, Ti and O elements were detected in the EDS analysis. The presence of TiO2effectively improved grain growth of the ZrO2ceramics. The Vickers hardness was in the range of 125 to 300 Hv and increased with the increase of TiO2contents. Sintering temperature dependence on the Vickers hardness was also investigated from 1150°C to 1300°C, showing the increase of Vickers hardness with the increase of the sintering temperature as well as TiO2addition.

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Effect of Short Time Sintering on the Mechanical Properties of Undoped Zirconia Ceramics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.629.420 ◽

2014 ◽

Vol 629 ◽

pp. 420-425 ◽

Cited By ~ 3

Author(s):

Sivanesan Sivakumar ◽

Ramesh Singh ◽

Hsien Loong Teow ◽

Yong Leng Chuan ◽

Jeffrey Kong Chin Leong

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Tetragonal Zirconia ◽

Matrix Stiffness ◽

Zirconia Ceramics ◽

High Relative Density ◽

The Matrix ◽

The Many ◽

Short Time ◽

Critical Grain Size

Sintering parameters are undoubtedly among the many factors that influence the mechanical properties and hydrothermal ageing resistance of tetragonal zirconia ceramics. In this research, the effect of using short holding times i.e. (1 min., 30 min. and 1 hour) as compared to the conventional 2 hours during sintering of 3 mol% Yttria Tetragonal Zirconia Polycrystals (3Y-TZP) on the mechanical properties were systematically investigated. The research revealed that holding time of 1 minute and sintered at 1400oC yielded a high relative density (above 95% of theoretical density) and high Young’s modulus (above 180 GPa) without compromising on tetragonal phase stability and mechanical properties. The study also revealed that the bulk density is an important parameter governing the matrix stiffness of 3Y-TZPs and that grain size strongly influences the transformability and consequently, the toughness of 3Y-TZPs. The toughness of the ceramic was observed to increase steeply when grains exceeded 0.52 µm, which has been identified as the critical grain size for toughening.

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Surface and Mechanical Characterization of Dental Yttria-Stabilized Tetragonal Zirconia Polycrystals (3Y-TZP) After Different Aging Processes

Microscopy and Microanalysis ◽

10.1017/s1431927616011843 ◽

2016 ◽

Vol 22 (6) ◽

pp. 1179-1188 ◽

Cited By ~ 10

Author(s):

Palena A. Pinto ◽

Guillaume Colas ◽

Tobin Filleter ◽

Grace M. De Souza

Keyword(s):

Mechanical Properties ◽

Phase Transformation ◽

Clinical Performance ◽

Tetragonal Zirconia ◽

Surface Hardness ◽

Compositional Analysis ◽

Hydrothermal Aging ◽

Experimental Conditions ◽

Force Microscopy ◽

Chewing Simulation

AbstractYttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) is a ceramic material used in indirect dental restorations. However, phase transformation at body temperature may compromise the material’s mechanical properties, affecting the clinical performance of the restoration. The effect of mastication on 3Y-TZP aging has not been investigated. 3Y-TZP specimens (IPS E-max ZirCAD and Z5) were aged in three different modes (n=13): no aging (control), hydrothermal aging (HA), or chewing simulation (CS). Mechanical properties and surface topography were analyzed. Analysis of variance showed that neither aging protocol (p=0.692) nor material (p=0.283) or the interaction between them (p=0.216) had a significant effect on flexural strength, values ranged from 928.8 MPa (IPSHA) to 1,080.6 MPa (Z5HA). Nanoindentation analysis showed that material, aging protocol, and the interaction between them had a significant effect (p<0.001) on surface hardness and reduced Young’s modulus. The compositional analysis revealed similar yttrium content for all the experimental conditions (aging: p=0.997; material: p=0.248; interaction material×aging: p=0.720). Atomic force microscopy showed an effect of aging protocols on phase transformation, with samples submitted to CS exhibiting features compatible with maximized phase transformation, such as increased volume of the material microstructure at the surface leading to an increase in surface roughness.

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PREPARATION OF DENSE TETRAGONAL ZIRCONIA CERAMICS FROM ZrO2 MICROPOWDERS

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1986135 ◽

1986 ◽

Vol 47 (C1) ◽

pp. C1-237-C1-241

Author(s):

A. SMITH ◽

B. CALES ◽

J. F. BAUMARD

Keyword(s):

Tetragonal Zirconia ◽

Zirconia Ceramics

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Effect of Accelerated Aging on Some Mechanical Properties and Wear of Different Commercial Dental Resin Composites

Materials ◽

10.3390/ma14112769 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2769

Author(s):

Jonne Oja ◽

Lippo Lassila ◽

Pekka K. Vallittu ◽

Sufyan Garoushi

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Accelerated Aging ◽

Wear Depth ◽

Resin Composites ◽

Expiration Date ◽

Dental Resin ◽

Hydrothermal Aging ◽

Dental Resin Composites

The aim of current in vitro research was to determine the effect of hydrothermal accelerated aging on the mechanical properties and wear of different commercial dental resin composites (RCs). In addition, the effect of expiration date of the composite prior its use was also evaluated. Five commercially available RCs were studied: Conventional RCs (Filtek Supreme XTE, G-aenial Posterior, Denfil, and >3y expired Supreme XTE), bulk-fill RC (Filtek Bulk Fill), and short fiber-reinforced RC (everX Posterior). Three-point flexural test was used for determination of ultimate flexural strength (n = 8). A vickers indenter was used for testing surface microhardness. A wear test was conducted with 15,000 chewing cycles using a dual-axis chewing simulator. Wear pattern was analyzed by a three-dimensional (3D) noncontact optical profilometer. Degree of C=C bond conversion of monomers was determined by FTIR-spectrometry. The specimens were either dry stored for 48 h (37 °C) or boiled (100 °C) for 16 h before testing. Scanning electron microscopy (SEM) was used to evaluate the microstructure of each material. Data were analyzed using ANOVA (p = 0.05). Hydrothermal aging had no significant effects on the surface wear and microhardness of tested RCs (p > 0.05). While flexural strength significantly decreased after aging (p < 0.05), except for G-aenial Posterior, which showed no differences. The lowest average wear depth was found for Filtek Bulk Fill (29 µm) (p < 0.05), while everX Posterior and Denfil showed the highest wear depth values (40, 39 µm) in both conditions. Passing the expiration date for 40 months did not affect the flexural strength and wear of tested RC. SEM demonstrated a significant number of small pits on Denfil’s surface after aging. It was concluded that the effect of accelerated aging may have caused certain weakening of the RC of some brands, whereas no effect was found with one brand of RC. Thus, the accelerated aging appeared to be more dependent on material and tested material property.

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