scholarly journals Ageing of Zirconia Dedicated to Dental Prostheses for Bruxers Part 1: Influence of Accelerating Ageing for Surface Topography and Mechanical Properties

2019 ◽  
Vol 58 (1) ◽  
pp. 189-194 ◽  
Author(s):  
Damian S. Nakonieczny ◽  
Marcin Basiaga ◽  
Agata Sambok ◽  
Magdalena Antonowicz ◽  
Zbigniew K. Paszenda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Surface Topography ◽  
Ageing Time ◽  
Accelerated Aging ◽  
Technical Requirements ◽  
Dental Prostheses ◽  
Ceramic Restorations ◽  
Dental Technology ◽  
Medical Grade

Abstract BACKGROUND: Zirconia is a commonly used ceramic for fixed full-ceramic restorations. Porcelain-fused-to-metal restorations applied for bruxers are often very quickly destroyed by this group of patients. OBJECTIVE: The aim of this study was to investigate the influence of accelerated aging tests on BruxZir HT 2.0 zirconia. METHODS: Zirconia samples were prepared with ISO 13356:2013 and ISO 14704:2008 protocol recommendations. The ageing conditions were times of 2.5, 5 and 10 hours, and pressure of 0.2 MPa and a temperature of 134°C. RESULTS: The correlation between ageing time and mechanical properties, particularly hardness, was difficult to find, while correlations between hardness and the surface topography and fracturing were clear. CONCLUSION: On the basis of the conducted research, it can be stated that BruxZir HT 2.0 zirconia meets the technical requirements for medical grade zirconia used in dental technology. Future investigations should include phase composition research.

scholarly journals Ageing of Zirconia Dedicated to Dental Prostheses for Bruxers Part 2: Influence of Heat Treatment for Surface Morphology, Phase Composition and Mechanical Properties

2019 ◽  
Vol 58 (1) ◽  
pp. 218-225
Author(s):  
Damian S. Nakonieczny ◽  
Agata Sambok ◽  
Magdalena Antonowicz ◽  
Marcin Basiaga ◽  
Zbigniew K. Paszenda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Phase Composition ◽  
High Temperature ◽  
Surface Morphology ◽  
Aging Process ◽  
Negative Impact ◽  
Bending Test ◽  
High Temperature Heat Treatment ◽  
Dental Prostheses

Abstract Purpose: This part of the study focuses on the influence of zirconia heat treatment for surface morphology, phase composition and mechanical properties Methods: Zirconia samples was prepared with ISO 13356:2013 and ISO 14704:2008 recommendations. X-ray diffraction, observations (SEM) and (AFM), microhardness (Olivera & Phara method), and static bending test (4PBT) were taken. Results: characterization of YSZ and high temperature heat treatment has clearly shown that the aging process influences the change in phase composition of the material, significantly worsening the topography. In turn, re-treatment of the high temperature made after the artificial aging process results in reverse transformation of the desired tetragonal phase, but does not affect the improvement of surface morphology. Conclusions: The research made it possible to assess the negative impact of the zirconium oxide aging simulation process. Because of the failure to achieve the intended results, it was also proved that the high-temperature re-processing was not appropriate.

Influence of CAD/CAM Grinding in the Performance of Sintered Dental Zirconia Framework

2012 ◽  
Vol 727-728 ◽  
pp. 1081-1084
Author(s):  
Carlos Nelson Elias ◽  
Andréa Mattos Melo ◽  
Claudinei dos Santos
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Surface Defects ◽  
Tetragonal Zirconia ◽  
Surface Cracks ◽  
Brittle Behavior ◽  
Dental Prostheses ◽  
Cad Cam ◽  
Ceramic Restorations ◽  
Tetragonal Zirconia Polycrystal

The brittle behavior of ceramics limits the use of these materials under conditions of cyclic loading, as is the case of fixed partial dentures. To improve toughness and biocompatibility of ceramics is necessary to employ powders with better purities, adjust the conditions of compaction and sintering, microstructure control and explore mechanisms for increasing the toughness. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is generally used for dental ceramic restorations. The zirconia framework is fabricated using the CAD/CAM system. The ceramic mechanical properties are determined by testing polished sample. Previous work did not analyze the influence of surface defects induced during dentures grinding. Ceramic restorations manufacturing are made with coarse grinding high-speed diamond rotatory cutting instruments. This process induces residual stresses and the high temperature induces surface cracks. Consequently, a lower strength and reliability of the material is observed. In this work the mechanical properties of yttria stabilized zirconia were determined with the use of samples of dental prostheses molded in patients and machined with the use of a dental laboratory CAD/CAM system. The results showed that the mechanical properties of pre-sintered blocks are different from prosthetics machined by CAD/CAM and sintered under the same conditions used in the laboratories of the prosthesis. The defects created during machining reduce the mechanical properties of zirconia.

Structure, Phase Composition, and Mechanical Properties of a Boron-Containing High-Nitrogen Austenitic Steel Made by Induction Melting

2020 ◽  
Vol 2020 (12) ◽  
pp. 1439-1445
Author(s):  
I. O. Bannykh ◽  
O. A. Bannykh ◽  
L. G. Rigina ◽  
E. N. Blinova ◽  
K. Yu. Demin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Austenitic Steel ◽  
Induction Melting ◽  
High Nitrogen ◽  
Structure Phase

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

Materials ◽  
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.

Microstructure and Mechanical Properties of Ti-6Al-4V Manufactured by SLM

2015 ◽  
Vol 651-653 ◽  
pp. 677-682 ◽  
Author(s):  
Anatoliy Popovich ◽  
Vadim Sufiiarov ◽  
Evgenii Borisov ◽  
Igor Polozov
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Phase Composition ◽  
Mechanical Behavior ◽  
Ductile Fracture ◽  
Elevated Temperatures ◽  
Initial Material ◽  
Laser Melting ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The article presents results of a study of phase composition and microstructure of initial material and samples obtained by selective laser melting of titanium-based alloy, as well as samples after heat treatment. The effect of heat treatment on microstructure and mechanical properties of specimens was shown. It was studied mechanical behavior of manufactured specimens before and after heat treatment at room and elevated temperatures as well. The heat treatment allows obtaining sufficient mechanical properties of material at room and elevated temperatures such as increase in ductility of material. The fractography of samples showed that they feature ductile fracture with brittle elements.

scholarly journals Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
O. I. Sekunowo ◽  
G. I. Lawal ◽  
S. O. Adeosun
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Ambient Temperature ◽  
Mechanical Response ◽  
Ageing Time ◽  
Thermal Ageing ◽  
Alloy Ingot ◽  
Solution Treated ◽  
Crucible Furnace

Samples of the 6063 (Al-1.09Mg2Si) alloy ingot were melted in a crucible furnace and cast in metal and sand moulds, respectively. Standard tensile, hardness, and microstructural test specimens were prepared from cast samples, solution treated at 520∘C, soaked for 6 hrs, and immediately quenched at ambient temperature in a trough containing water to assume a supersaturated structure. The quenched specimens were then thermally aged at 175∘C for 3–7 hrs. Results show that at different ageing time, varied fractions of precipitates and intermetallics evolved in the specimens’ matrices which affect the resulting mechanical properties. The metal mould specimens aged for four hours (MTA-4) exhibited superior ultimate tensile strength of 247.8 MPa; microhardness, 68.5 HV; elongation, 28.2% . It is concluded that the extent of improvement in mechanical properties depends on the fractions, coherence, and distribution of precipitates along with the type of intermetallics developed in the alloy during ageing process.

Phase composition and mechanical properties of alloys of the Al-Mg-Li-Me system

2008 ◽  
Vol 50 (1-2) ◽  
pp. 80-82 ◽  
Author(s):  
L. V. Tarasenko ◽  
N. I. Kolobnev ◽  
L. B. Khokhlatova
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Alloys Of The Al
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