Properties of Mullite-Zirconia Composites Prepared through Reaction Sintering Kaolin, α-Al2O3, and ZrO2

2010 ◽  
Vol 160-162 ◽  
pp. 1772-1778 ◽  
Author(s):  
F. Sahnoune ◽  
N. Saheb ◽  
P. Goeuriot
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Coefficient Of Thermal Expansion ◽  
Testing Machine ◽  
Tetragonal Zirconia ◽  
Quantitative Phase Analysis ◽  
Reaction Sintering ◽  
Zro2 Content ◽  
Linear Coefficient ◽  
Zirconia Composites

Mullite–zirconia composites were synthesized through reaction sintering Algerian kaolin, α-Al2O3, and ZrO2. Phases present and their transformations were characterized using x-ray diffraction. Quantitative phase analysis was performed following the Rietveld method. Hardness and fracture toughness were measured by Vickers indentation. The flexural strength was measured using a Universal Testing Machine. It was found that the microstructure of samples sintered for 2 hours at 1600°C was composed of mullite grains which have whiskers’ shape and ZrO2 particles. In the composite containing 16 wt.% ZrO2, the ratio of tetragonal zirconia transformed to monoclinic zirconia was relatively small and did not exceed 18%. However, in the composite containing 32 wt.% ZrO2 around 75% of the tetragonal structure changed to monoclinic structure. Also, it was found that the increase of ZrO2 content from 0 to 32 wt.% decreased the microhardness of the composites from 14 to 10.8 GPa. However, the increase of ZrO2 content from 0 to 24wt.% increased the flexural strength of the composites from 142 to 390 MPa then decreased it with further increase of ZrO2 content. The fracture toughness increased from 1.8 to 2.9 MPa.m1/2 with the increase of ZrO2 content from 0 to 32 wt.%; and the rate of the increase decreased at higher fractions of ZrO2 content. The average linear coefficient of thermal expansion (within the range 50 to 1450°C) for samples containing 0 and 16 wt.% ZrO2 sintered at 1600°C for 2 hours was 4.7 x10-6 K-1 and 5.2 x 10-6 K-1 respectively.

Impact of Different Fiber Reinforcement on Flexural Strength, Fracture Toughness and Abrasive Resistance of Provisional Restorative Resin

2021 ◽  
Author(s):  
Dr. Pratik Bhatnagar
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Clinical Performance ◽  
Testing Machine ◽  
Surface Hardness ◽  
Abrasive Resistance ◽  
Significance Level ◽  
Post Hoc ◽  
The Impact

Aim: To assess and compare the impact of reinforcement of PMMA with glass fibre, polyethylene fibre and carbon fibres on flexural strength, fracture toughness and abrasive resistance. Background: In view of inadequate mechanical and physical characteristics of PMMA which include low impact strength and low surface hardness and resulting lowered clinical performance of the prosthesis, the study was designed to investigate the impact of reinforcement of PMMA with glass, polyethylene and carbon fibers on flexural strength, fracture toughness and abrasive resistance. Methods and Findings: Rectangular specimens (n=120; 30 each from 4 groups; 65 × 10 × 3.3 mm3) were fabricated and loaded on Universal Testing Machine until fracture for flexural strength and fracture toughness and on Taber Abrasive Tester for abrasive resistance. Data were analyzed using one–way ANOVA followed by Post Hoc test - Bonferroni multiple comparison analysis, using significance level of 0.05. Significant increase in fracture toughness was observed in specimens reinforced with polyethylene and carbon fiber, albeit the values of flexural strength were increased insignificantly. Specimens reinforced with glass and carbon fiber had significantly low values of abrasive resistance. Conclusion: Findings indicate that reinforcement of PMMA by non-specific fibers like glass, polyethylene and carbon resulted in significant increase in fracture toughness and decrease in abrasive resistance.

Flexural strength, fracture toughness, and translucency of cubic/tetragonal zirconia materials

2018 ◽  
Vol 120 (6) ◽  
pp. 948-954 ◽  
Author(s):  
Parissa Nassary Zadeh ◽  
Nina Lümkemann ◽  
Beatrice Sener ◽  
Marlis Eichberger ◽  
Bogna Stawarczyk
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Tetragonal Zirconia

Effect of TiN Addition on Microstructure and Mechanical Properties of Zirconia Matrix Ceramic Tool Material

2004 ◽  
Vol 471-472 ◽  
pp. 321-325 ◽  
Author(s):  
Jing Sun ◽  
Chuan Zhen Huang ◽  
Han Lian Liu ◽  
Sui Lian Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Monoclinic Phase ◽  
Tetragonal Zirconia ◽  
Tool Material ◽  
Strengthening Mechanisms ◽  
Microstructure And Mechanical Properties ◽  
Ceramic Tool Material ◽  
Tetragonal Zirconia Polycrystal

In this paper, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) and TiN/3Y-TZP(adding TiN particles to 3Y-TZP) composites were fabricated by hot-pressing technique. Phase composition, microstructure and mechanical properties of the composites were investigated. It is shown that the flexural strength, fracture toughness and Vickers hardness of TiN/3Y-TZP was significantly improved by the addition of TiN particles compared with 3Y-TZP. The flexural strength of ZYT2 (20wt% TiN addition) is 1318 MPa. The fracture toughness of ZYT4 (40wt% TiN addition) is 16.8MPa·m1/2. The toughening and strengthening mechanisms were analyzed. The XRD results show that the additing of TiN can hinder the transformation from tetragonal phase to monoclinic phase of 3Y-TZP during fabrication process.

Effect of Nano-Oxide Addition on Mechanical Properties of Alumina-Mullite-Zirconia Composites

2015 ◽  
Vol 1102 ◽  
pp. 87-90
Author(s):  
Anurat Poowancum ◽  
Sukasem Watcharamaisakul
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Mechanical Tests ◽  
Oxide Addition ◽  
Nano Oxide ◽  
Zirconia Composites ◽  
Microstructure Density ◽  
Sintering Method

This work reports on the effect of CeO2 and Cr2O3 addition on the mechanical properties of Al2O3-mullite-ZrO2 composites. The amount of additives added was 1.5wt%CeO2, 1.5wt%Cr2O3 and the mixture of 1.5wt%CeO2 and 1.5 wt%Cr2O3. Bulk composites have been sintered by using pressure-less sintering method. Phases, microstructure, density and porosity of sintered composites were characterized. Flexural strength and fracture toughness were also determined. The results from mechanical tests showed that the highest flexural strength was obtained with the mixture of CeO2 and Cr2O3 addition, while the highest fracture toughness was obtained with CeO2 addition.

Mechanical Properties of SiC/FexSiy Composites

2011 ◽  
Vol 236-238 ◽  
pp. 1523-1527 ◽  
Author(s):  
Xiao Meng Zhang ◽  
Shu Feng Ye ◽  
Li Hua Xu ◽  
Peng Qian ◽  
Lian Qi Wei ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Raw Material ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Scanning Electron

The SiC/FexSiycomposites were synthesized by reaction sintering process with iron tailings as raw material and carbon as reductant. The room and high temperature flexural strengths and fracture toughness of composites were studied in this paper. Fracture surfaces were observed by means of a scanning electron microscope (SEM). The results showed that the room temperature flexural strength of SiC/FexSiycomposites changed along with the different contents of FexSiyand sintering temperature. The flexural strength of composites reaches the maximum at 900°C. The correlation between flexural strength and temperature is consistent with curveⅠ.The fracture toughness of composites is related to the content of FexSiy. The fracture behavior of composites is mainly transcrystalline in room temperature and intercrystalline in high temperature.

scholarly journals Fracture Toughness Comparison of Three Indirect Composite Resins Using 4-Point Flexural Strength Method

2020 ◽  
Vol 14 (02) ◽  
pp. 212-216 ◽  
Author(s):  
Zohreh Moradi ◽  
Mahdi Abbasi ◽  
Rayhaneh Khalesi ◽  
Masoumeh Hasani Tabatabaei ◽  
Zahra Shahidi
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Statistical Power ◽  
Testing Machine ◽  
Composite Resins ◽  
Volume Percentage ◽  
Composite Restorations ◽  
Significant Difference ◽  
Computer Aided ◽  
Indirect Composite

Abstract Objectives The advantages of indirect composite restorations such as less crack formation during their computer-aided design/computer-aided manufacturing process, compared with ceramic restorations, have resulted in their growing popularity. However, restoration failure is a major concern with regard to the long-term clinical success of restorations and may occur as the result of propagation of a crack originated from an internal flaw in the restoration. This study aimed to compare the fracture toughness of three indirect composite resins. Materials and Methods In this in vitro experimental study, 10 specimens measuring 3 × 3 × 18 mm were fabricated of Gradia, Crios, and high impact polymer composite indirect composites. A single edge notch with a diameter < 0.3 mm and 0.3 mm length was created in the 9 mm longitudinal dimension of specimens using a no. 11 surgical scalpel. The specimens were then subjected to 4-point flexural strength test in a universal testing machine with a crosshead speed of 0.1 mm/s until failure. Statistical Analysis Data were analyzed using IBM SPSS Statistics via one-way analysis of variance (ANOVA) and Tukey’s HSD (honestly significant difference) test. The statistical power was set at p ˂ 0.05. Results One-way ANOVA showed a significant difference in fracture toughness of the three composite groups (p = 0.000). According to the Tukey HSD analysis, the fracture toughness of HIPC was significantly higher than that of the other two composites. The fracture toughness of Gradia was significantly lower among all. Conclusions Within the limitations of this study, the results showed that high temperature-pressure polymerization can increase resistance to crack propagation and subsequently improve the clinical service of indirect composite restorations. Although we do not know the filler volume percentage of HIPC, it seems that filler volume percentage of the composite is inversely correlated with fracture toughness.

Investigation into the Mechanical Properties of Nanometric Zirconia Dental Ceramics

2011 ◽  
Vol 211-212 ◽  
pp. 31-35 ◽  
Author(s):  
Ya Li Hou ◽  
Chang He Li ◽  
Li Li Wang ◽  
Yu Cheng Ding
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Testing Machine ◽  
Apparent Porosity ◽  
Length Variation ◽  
Dental Ceramics ◽  
Linear Contraction ◽  
Before And After

This study was focused on the testing and assessment of the mechanical properties of nanometric zirconia dental ceramics. The density and the apparent porosity of specimens were tested with the Archimedes drainage method. The length variation of the specimens before and after sintering was measured with a vernier caliper, and the linear contraction was tested. An X-ray diffractometer was used for the specimen phase analysis. SEM was used to observe the section micrograph of the specimens. A universal mechanical testing machine was used to test the three-point flexural strength and the fracture toughness. A microhardness tester was used to test the Vickers hardness of the test specimens. Results indicates that the flexural strength of the test specimens ≥ 890MPa, the fracture toughness ≥6Mpa.m1/2, the Vickers hardness ≥ 1240MPa, the linear contraction ≥ 21%, and the apparent porosity ≥ 0.32%. Fully satisfying the requirements in oral medicine, the ceramic is an ideal material for biological joints and dental prosthesis.

Mechanical Properties and Microstructure of Reaction Sintering B4C/SiC Ceramics

2011 ◽  
Vol 66-68 ◽  
pp. 510-515
Author(s):  
Wen Song Lin ◽  
Ning Xiang Fang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Carbon Content ◽  
Sintering Temperature ◽  
Reaction Sintering ◽  
Sic Ceramics ◽  
Compact Pressure ◽  
Optimal Value ◽  
Major Factors

Reaction sintering B4C/SiC ceramics with high density were manufactured. The effect of the carbon content in green bodies on the microstructure and mechanical properties of the ceramics has been studied. Results showed that the carbon content and the value of carbon relative density (ρCRD) in the green bodies were the major factors affected the composition, that is, the free silicon and carbon contents and mechanical behaviors of sintered specimens. The optimal value of ρCRD was gotten at 0.85 g/cm3. The fracture toughness, flexural strength, and hardness of the composites increased with increasing carbon content up to 20 wt.%. The maximum values of fracture toughness of 3.8 MPa∙m1/2, flexural strength of 475 MPa, and hardness of 32.0 GPa were obtained under the following process parameters: value of ρCRD in the green bodies was about 0.85 g/cm3; carbon, B4C and SiC contents in green bodies were 20 wt.%, 30 wt.% and 50 wt.%, respectively; compact pressure was 75 MPa and sintering temperature was 1600°C.

Reaction sintering and mechanical properties of B4C with addition of ZrO2

2000 ◽  
Vol 15 (11) ◽  
pp. 2431-2436 ◽  
Author(s):  
Hae-Won Kim ◽  
Young-Hag Koh ◽  
Hyoun-Ee Kim
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Elevated Temperatures ◽  
Applied Pressure ◽  
Sintering Behavior ◽  
Reaction Sintering ◽  
Densification Behavior ◽  
High Relative Density ◽  
Full Densification

The effect of ZrO2 addition on sintering behavior and mechanical properties of both hot-pressed and pressureless-sintered B4C was investigated. The addition of ZrO2 improved the densification behavior of B4C remarkably via a reaction with the B4C to form ZrB2 at elevated temperatures. When B4C was densified at 2000 °C by hot pressing, only a small amount (approximately 2.5 vol%) of ZrO2 was necessary to achieve a full densification. Excellent mechanical properties (hardness, elastic modulus, flexural strength, and fracture toughness) were observed in those specimens. As the amount of ZrO2 was increased further, the mechanical properties were reduced, except for the fracture toughness, apparently due to the formation of too much ZrB2 in the specimen. Without the applied pressure, larger amounts of ZrO2 should be added to obtain a body with high relative density. When the B4C was sintered at 2175 °C with addition of 10 vol% ZrO2, the specimen has a density higher than 95% of the theoretical, and hardness and flexural strength of 25 GPa and 400 MPa, respectively.

scholarly journals The effect of nano-TiO2 addition on the properties of mullite-zirconia composites prepared by slip casting

2012 ◽  
Vol 44 (3) ◽  
pp. 341-354 ◽  
Author(s):  
S.H. Badiee ◽  
S. Otroj ◽  
M. Rahmani
Keyword(s):  
Phase Composition ◽  
Flexural Strength ◽  
Physical Properties ◽  
Slip Casting ◽  
Reaction Sintering ◽  
Casting Method ◽  
Nano Tio2 ◽  
Zircon Powder ◽  
Zirconia Composites ◽  
Tio2 Addition

The mullite-zirconia composites were prepared by reaction-sintering of alumina and zircon powder. Besides, the slip casting method was employed for fabrication of these composites. Then, the effect of nano-TiO2 addition on the properties of these composites was investigated and the results were compared with micro-sized TiO2. Hence, the physical properties, phase composition, flexural strength and microstructure of these composites after firing at 1600?C were studied. The results showed that the flexural strength of composite tends to increase with the addition of 0.5 wt.% nano-TiO2. It is attributed to the formation of larger size rod-like ZrO2 and enhanced ceramic bonding between them.

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