Effects of sintering time and hydrothermal aging on the mechanical properties of monolithic zirconia ceramic systems

2020 ◽  
Author(s):  
Perihan Oyar ◽  
Rukiye Durkan ◽  
Gonca Deste
Keyword(s):  
Mechanical Properties ◽  
Zirconia Ceramic ◽  
Hydrothermal Aging ◽  
Sintering Time ◽  
Monolithic Zirconia

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.

scholarly journals Effect of Graphene Nanosheets Content on Microstructure and Mechanical Properties of Titanium Matrix Composite Produced by Cold Pressing and Sintering

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1024 ◽  
Author(s):  
Milad Haghighi ◽  
Mohammad Shaeri ◽  
Arman Sedghi ◽  
Faramarz Djavanroodi
Keyword(s):  
Mechanical Properties ◽  
Matrix Composite ◽  
Volume Fraction ◽  
Graphene Nanosheets ◽  
Microstructural Analysis ◽  
Titanium Matrix ◽  
Titanium Matrix Composite ◽  
Cold Pressing ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties

The effect of graphene nanosheet (GNS) reinforcement on the microstructure and mechanical properties of the titanium matrix composite has been discussed. For this purpose, composites with various GNS contents were prepared by cold pressing and sintering at various time periods. Density calculation by Archimedes’ principle revealed that Ti/GNSs composites with reasonable high density (more than 99.5% of theoretical density) were produced after sintering for 5 h. Microstructural analysis by X-ray diffraction (XRD) and a field emission scanning electron microscope (FESEM) showed that TiC particles were formed in the matrix during the sintering process as a result of a titanium reaction with carbon. Higher GNS content as well as sintering time resulted in an increase in TiC particle size and volume fraction. Microhardness and shear punch tests demonstrated considerable improvement of the specimens’ mechanical properties with the increment of sintering time and GNS content up to 1 wt. %. The microhardness and shear strength of 1 wt. % GNS composites were enhanced from 316 HV and 610 MPa to 613 HV and 754 MPa, respectively, when composites sintered for 5 h. It is worth mentioning that the formation of the agglomerates of unreacted GNSs in 1.5 wt. % GNS composites resulted in a dramatic decrease in mechanical properties.

scholarly journals Biaxial flexural strength of different types of monolithic zirconia

2019 ◽  
Vol 22 (1) ◽  
pp. Process
Author(s):  
Shereen Ahmed Nossair ◽  
Tarek Salah ◽  
Kamal Khaled Ebeid
Keyword(s):  
Flexural Strength ◽  
Zirconia Ceramic ◽  
Group 4 ◽  
Dental Esthetics ◽  
Biaxial Flexural Strength ◽  
Different Types ◽  
Monolithic Zirconia ◽  
Group 5 ◽  
Group 2 ◽  
Post Hoc

Objective: This study was designed to evaluate the biaxial flexural strength (BFS) of different types of unshaded and shaded monolithic zirconia. Material and Methods: 120 monolithic zirconia ceramic discs were fabricated. They were divided into twelve groups (n=10), Group 1; Bruxzir unshaded, Group 2; Bruxzir shaded A2, Group 3; Bruxzir anterior white, Group 4; Bruxzir anterior shade A2, Group 5; Prettau unshaded, Group 6; Prettau shaded with A2 coloring liquid, Group 7; Prettau anterior white, Group 8; Prettau anterior shaded with A2 coloring liquid, Group 9; Katana HT white, Group 10; Katana HT shade A2, Group 11; Katana ST white, Group 12; Katana ST shade A2. All discs were milled using a dental milling machine, and had final dimensions after sintering of 15 mm diameter and 1 mm thickness. BFS was tested using piston on three ball technique. Results:  One-way ANOVA revealed significant differences among the 12 groups. Tukey post-hoc tests revealed no significant differences between the groups 3, 4, ,7 ,8 11, and 12. However, they all had BFS values that are significantly lower than all other groups. Group 2 showed statistically significant higher BFS values when compared to group 3,4, 7, 8, 11, and 12 while it showed statistically significant lower values when compared to groups 1, 5, 6, 9, and 10. Conclusion: Increase in the yttria content in zirconia led to a decrease in its BFS. Shading of zirconia did not have a significant effect on the final strength of zirconia. KeywordsDental ceramics; Dental esthetics; Flexural strength; Shaded zirconia. 

scholarly journals Synthesis of "in situ" reinforced silicon nitride composites

2004 ◽  
Vol 69 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Aleksandra Vuckovic ◽  
Snezana Boskovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Pressureless Sintering ◽  
Sintering Additives ◽  
Sintering Time

The objective of this work was to investigate the effect of two different sintering additives (CeO2 and Y2O3 + Al2O3), sintering time and amount of ?-Si3N4 seeds on the densification, mechanical properties and microstructure of self-reinforced Si3N4 based composites obtained by pressureless sintering. Preparation of ?-Si3N4 seeds, also obtained by a pressureless sintering procedure, is described. Samples without seeds were prepared for comparison. The results imply that self-reinforced silicon nitride based composites with densities close to the theoretical values and with fracture toughness of 9.3MPa m1/2 can be obtained using a presureless sintering procedure.

scholarly journals The Aging Time Effects of the Pre-expanded Polystyrene on the Patterns Mechanical Properties

2015 ◽  
Vol 15 (1) ◽  
pp. 131-137 ◽  
Author(s):  
K. Buczkowska ◽  
T. Pacyniak
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Manufacturing Process ◽  
Smooth Surface ◽  
Raw Materials ◽  
Expanded Polystyrene ◽  
Optimum Time ◽  
Time Effects ◽  
Blowing Agent ◽  
Sintering Time

Abstract The aging granulate is to activate the blowing agent during the manufacturing process to granulate models can re-expand and shape the model of well-sintered granules, smooth surface and a suitable mechanical strength. The article presents the results of studies which aim was to determine the optimum time for aging pre-foamed granules for pre-selected raw materials. The testing samples were shaped in an autoclave, with constant parameters sintering time and temperature. Samples were made at 30 minute intervals. Models have been subjected to flexural strength and hardness.

Effects of Hydrothermal Treatment on the Phase Transformation, Surface Roughness, and Mechanical Properties of Monolithic Translucent Zirconia

2022 ◽  
Author(s):  
CY Zhang ◽  
C Agingu ◽  
H Yang ◽  
H Cheng ◽  
H Yu
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Hydrothermal Treatment ◽  
Cross Sections ◽  
Monoclinic Phase ◽  
Control Group ◽  
Hydrothermal Aging ◽  
Characteristic Strength

SUMMARY Objectives: This study aimed to investigate the effects of hydrothermal treatment on four types of monolithic, translucent, yttria-stabilized, tetragonal zirconia polycrystals (Y-TZPs). Methods and Materials: Two commercially available Y-TZP brands—SuperfectZir High Translucency (Aidite Technology Co, China) and Katana HT (Kuraray Noritake Dental, Japan) were assessed. For each brand of Y-TZP, materials of four coloring types, including noncolored (NC), colored by staining (CS), precolored (PC), and multilayered (ML) specimens were investigated after hydrothermal aging in an autoclave at 134°C/0.2 MPa for 0 (control group), 5, 10, and 20 hours. The tetragonal-to-monoclinic phase transformation, surface roughness, flexural strength, and structural reliability (Weibull analysis) were measured and statistically analyzed (α=0.05). The subsurface microstructure was analyzed with scanning electron microscopy. Results: The group ML exhibited the lowest flexural strength and Weibull characteristic strength among the four coloring types (p&lt;0.05). Slight increases in the monoclinic phase volume, flexural strength, and Weibull characteristic strength were observed after hydrothermal aging (pall&lt;0.05). Regardless of coloring type, no significant effects of aging on the Weibull modulus or surface roughness were found for the tested materials. Compared with the Katana HT cross-sections, the SuperfectZir High Translucency cross-sections exhibited a similar but thicker transformation zone. Conclusions: The coloring procedure and material type were found to affect the mechanical properties and aging resistance of translucent monolithic Y-TZP ceramics. Regardless of the aging time, the surface roughness of the tested Y-TZP ceramics remained unchanged.

scholarly journals Effect of Hydrothermal Aging and Beverages on Color Stability of Lithium Disilicate and Zirconia Based Ceramics

Medicina ◽  
2019 ◽  
Vol 55 (11) ◽  
pp. 749 ◽  
Author(s):  
Satheesh B. Haralur ◽  
Noura Raqe S. Alqahtani ◽  
Fatimah Alhassan Mujayri
Keyword(s):  
Green Tea ◽  
In Vitro Study ◽  
Color Stability ◽  
Lithium Disilicate ◽  
Color Difference ◽  
Hydrothermal Aging ◽  
Monolithic Zirconia ◽  
Post Hoc ◽  
Coloring Agents

Background and aim: All-ceramic prosthesis is widely used in modern dental practice because of its improved physico-mechanical and optical properties. These restorations are exposed to coloring agents from various nutrition and beverages in the oral cavity. Long-term color stability is critical for the success of these restorative materials. The purpose of this in vitro study was to assess the effect of common beverages and mouthwash on the color stability of lithium disilicate (LD), monolithic zirconia (MZ) and bilayer zirconia (BZ) surfaces. Material and methods: Thirty disc-shaped specimens from each material were fabricated; each group was subdivided (n = 10) according to coffee, green tea and chlorhexidine immersion solutions. The baseline color of ceramic discs was recorded according to the CIE L*a*b* system with a portable spectrophotometer. The second measurement was recorded after 3000 thermocycling and immersion in coloring agents for 7 days. The mean color difference was calculated and data were compared with Kruskal-Wallis and Mann-Whitney post hoc tests (0.05). Results: ΔE values for LD with the immersion of coffee, tea, and Chlorhexidine gluconate (CHG) were 1.78, 2.241 and 1.58, respectively. Corresponding ΔE values for MZ were 5.60, 5.19, and 4.86; marginally higher than the clinically acceptable level of 3.5. Meanwhile, BZ showed better color stability compared to MZ with ΔE values of 4.22, 2.11 and 1.43. Conclusion: Among the ceramics evaluated, LD ceramic was found to be more color stable, while MZ ceramics displayed a higher susceptibility to discoloration. MZ and BZ ceramic colors were significantly altered with coffee immersion, while LD ceramics were more affected by green tea.

Translucency of Monolithic Zirconia after Hydrothermal Aging: A Review of In Vitro Studies

2020 ◽  
Vol 29 (6) ◽  
pp. 489-500 ◽  
Author(s):  
Katerina Papageorgiou‐Kyrana ◽  
Maria Fasoula ◽  
Eleana Kontonasaki
Keyword(s):  
In Vitro Studies ◽  
Hydrothermal Aging ◽  
Monolithic Zirconia
Sign in / Sign up

Export Citation Format

Share Document