Effect of Age-Induced Transparency on the Mechanical Properties of Human Dentin

2005 ◽  
Vol 874 ◽  
Author(s):  
Ravi K. Nalla ◽  
John H. Kinney ◽  
John A. Pople ◽  
Thomas M. Breunig ◽  
Antoni P. Tomsia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Crystallite Size ◽  
Fatigue Behavior ◽  
High Stress ◽  
Mineral Concentration ◽  
X Ray ◽  
Human Dentin ◽  
The Difference ◽  
Induced Transparency

AbstractMost non-traumatic fractures occur in teeth that have been treated, for example restored or endodontically repaired. It is therefore essential to evaluate the structure and mechanical properties of altered forms of dentin. One such altered dentin is transparent (sclerotic) dentin, which forms gradually with aging. Accordingly, in the present study, we seek to study differences in the structure, i.e., dentinal mineral concentration, mineral crystallite size, and the mechanical properties, i.e., elastic moduli, fracture toughness and fatigue behavior, of normal and transparent root dentin. The mineral concentration, measured by x-ray computed tomography, was found to be significantly higher in transparent dentin, with the majority of the increase being due to the closure of the tubule lumens. Crystallite size, as measured by small angle x-ray scattering, appeared to be slightly reduced in transparent dentin, although the difference was not statistically significant. The elastic properties remained unchanged, although transparent dentin showed almost no yield/post-yield behavior. The fracture toughness was lowered by roughly 20%, while the fatigue resistance was deleteriously affected at high stress levels. These results are discussed in terms of the altered microstructure of transparent dentin.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3-TiC-ZrO2 Ceramic Composites

2012 ◽  
Vol 476-478 ◽  
pp. 1031-1035
Author(s):  
Wei Min Liu ◽  
Xing Ai ◽  
Jun Zhao ◽  
Yong Hui Zhou
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Al2O3-TiC-ZrO2ceramic composites (ATZ) were fabricated by hot-pressed sintering. The phases and microstructure of the composites were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relative density and mechanical properties (flexural strength, fracture toughness and Vicker’s hardness) of the composites were tested. The results show that the microstructure of the composites was the gray core-white rim. With the increase of sintering temperature, the relative density and mechanical properties of the composites increased first and then decreased. The composite sintered at 1705°C has the highest synthetical properties, and its relative density, flexural strength, fracture toughness and Vickers hardness are 98.3%,970MPa,6.0 MPa•m1/2and 20.5GPa, respectively.

Mechanical Behavior of the Cr3C2 Compound at High Pressure and High Temperature

2015 ◽  
Vol 1120-1121 ◽  
pp. 1187-1193 ◽  
Author(s):  
Bin Li Jiang ◽  
Zi Li Kou ◽  
De Jiang Ma ◽  
Yong Kun Wang ◽  
Chun Xia Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Pressure ◽  
Relative Density ◽  
X Ray Diffraction ◽  
Density Measurements ◽  
X Ray ◽  
Hardness Tests ◽  
Novel Method ◽  
Heat Preservation

In the present study, we present a novel method to sinter Cr3C2 powders under high pressure without any addittives. The sintering Cr3C2 samples were charaterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), relative density measurements, Vicker’s hardness tests and Fracture toughness tests. The reasults show that Cr3C2 powders could be sintered to be bulk under the conditions of 3-5 GPa, 800-1200 °C and the heat preservation for 15 min. Moreover, the sintering body of Cr3C2 compound with the relative density of 99.84% by simultaneously tuning the pressure-temperature conditions exhibited excellent mechanical properties: a Vickers hardness of 20.3 GPa and a fracture toughness of ~8.9 MPam1/2. These properties were much higher than that by using the previous methods. The temperature condition obtained good mechanical properties in the experiment was about 1/3 lower than that using any other methods owing to the high pressure.

Effect of the Ratio of Co to Ni+Co on the Microstructures and Mechanical Properties of Ti(C, N)-Based Cermets

2017 ◽  
Vol 726 ◽  
pp. 292-296 ◽  
Author(s):  
Peng Wu ◽  
Shao Cun Liu ◽  
Xiu Rong Jiang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rupture Strength ◽  
Hard Particle ◽  
Core Size ◽  
Transverse Rupture Strength ◽  
X Ray ◽  
The Core ◽  
Scanning Electron

The microstructures of the prepared Ti(C, N)-based cermets with various ratios of Co to Ni+Co were studied using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Mechanical properties such as transverse rupture strength (TRS), fracture toughness (K1C) and hardness (HRA) were also measured. The results showed that when Ni was partly replaced by Co, the core size of hard particle and the thickness of rim phase changed. With the increasing of the ratio of Co to Ni+Co, the porosity of the cermets increased gradually, the fracture toughness of the cermets decreased gradually, the transverse rupture strength increased firstly and then decreased, the hardness changed slightly。When the ratio of Co to Ni+Co was 0.2, the cermets had better transverse rupture strength (TRS), which was characterized by fine grains and the moderate thickness of rim phase in the binder.

scholarly journals Effect of Silica Addition on Mechanical Properties of Eggshell-Derived Hydroxyapatite

2021 ◽  
Vol 10 (2) ◽  
pp. 129-138
Author(s):  
. Fatma ◽  
. Desnelli ◽  
Fahma Riyanti ◽  
Mustafa Kamal ◽  
Muhammad Ramdan Abdul Mannan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Crystallite Size ◽  
Fourier Transform Infrared Spectroscopy ◽  
Biomedical Applications ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silica Addition

Eggshell is a solid waste that is available in abundance but is being left unused. Eggshell containing calcium in a high amount. Calcium can be used as a precursor for hydroxyapatite (HAp). Modification of HAp with SiO2 is expected to improve its low mechanical properties for biomedical applications. In this study, HAp is synthesized from the eggshell. Then, it was modified by adding SiO2 utilizing the coprecipitation method with concentrations of 10%, 20%, 30%, and 40%, respectively. The HAp and HAp/SiO2 were characterized using; X-ray diffraction and Fourier transform infrared spectroscopy. The analysis HAp and HAp/SiO2 were density, compressive strength, and hardness. The best mechanical properties of HAp/SiO2 were characterized using SEM-EDS. The HAp were prepared successfully with a ratio of Ca/P was 1.673, close to the theoretical 1.67. The addition of SiO2 caused a decrease in crystallite size and density but increased compressive strength and hardness. The best mechanical properties of HAp/SiO2 were obtained with SiO2 of 30% and 40% with similar values.

Techniques of SrAl12O19 Platelets Formation in ZTA

2015 ◽  
Vol 788 ◽  
pp. 246-251
Author(s):  
Natalya Belousova ◽  
Sergey Veselov ◽  
Nina Cherkasova ◽  
Aleksey Lazarev ◽  
Ruslan Kuzmin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Ceramic Material ◽  
Ceramic Materials ◽  
Mechanical Tests ◽  
Initial Material ◽  
X Ray Diffraction ◽  
Sintered Ceramic ◽  
X Ray ◽  
Platelet Formation

A possibility of the SrAl12O19platelet formation in the Al2O3– ZrO2ceramic using SrCO3or Sr3Al2O6is evaluated. An impact of two techniques of platelet synthesis on mechanical properties of the material is investigated. Defects revealed in the sintered ceramic material are analyzed. Recommendations on the best method of the SrAl12O19phase formation in ceramic materials are given based on the structural and X-ray diffraction analyses as well as on mechanical tests. It is shown that an addition of 3 wt% SrAl12O19into the ZTA ceramic results in an increase in fracture toughness by up to 30 % in comparison with the initial material.

Effect of graphite addition on mechanical properties of Al2O3 ceramics by directed laser deposition

2020 ◽  
pp. 095440542094480
Author(s):  
Yuan Xu ◽  
Chao Yu ◽  
Qiu-yu Miao ◽  
Shuai Yan ◽  
Guang-yi Ma
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Lower Cost ◽  
Ceramic Materials ◽  
Laser Deposition ◽  
High Toughness ◽  
The Difference ◽  
Rapid Manufacture ◽  
Forming Defects ◽  
New Phase

In this article, graphite-reinforced Al2O3 ceramic materials were prepared by directed laser deposition. The effects of graphite addition (3–12 wt.%) on the phase composition, microhardness and fracture toughness of Al2O3 ceramics were studied. The results showed that the process was beneficial for maintaining uniform mixing of graphite and ceramics and thus could avoid the delamination caused by the difference in their densities. When adding 6% and 9% graphite, there were fewer internal defects in the samples, and no obvious new phase was generated after adding more graphite. The microhardness of 6% and 9% graphite-reinforced Al2O3 ceramics reached 18.84 and 18.86 GPa, respectively, and it was close to that of pure Al2O3 ceramics. The microhardness of all graphite-reinforced Al2O3 materials was lower than that of pure Al2O3 ceramics, but the value increased first and then decreased with addition of more graphite. The change in microhardness was similar to the trend of the number of defects, thus, these newly forming defects were an important factor affecting the microhardness. With an increase in graphite addition, the fracture toughness increased gradually. Furthermore, the fracture toughness reached 5.89 MPa m1/2 at 12% graphite addition, which was higher than 4.82 MPa m1/2 of pure Al2O3 ceramics. Adding more graphite was beneficial in enhancing the deflection and pinning of the graphite particles against cracks, resulting in higher fracture toughness. Graphite can improve the fracture toughness of Al2O3 ceramic, prepared by directed laser deposition, and the method can solve the uneven distribution caused by the difference in densities between the two powders. This also provides a new idea for the rapid manufacture of high-toughness ceramic parts at lower cost.

Effect of La2O3-Rich Glass Addition on Sintering of Zirconia Based Ceramics

2008 ◽  
Vol 587-588 ◽  
pp. 104-108
Author(s):  
Claudinei dos Santos ◽  
R.C. Souza ◽  
Maria Helena F.V. Fernandes ◽  
Nuno A.F. Almeida ◽  
Flávia A. Almeida ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tetragonal Zirconia ◽  
X Ray Diffraction ◽  
Indentation Method ◽  
Glass Addition ◽  
X Ray ◽  
Heating And Cooling ◽  
Mesh Screen ◽  
Cold Pressed

In this study, the influence of La-rich glass addition and sintering conditions on the densification and mechanical properties of 3 mol.%Y2O3-stabilized tetragonal zirconia polycrystals (3Y-TZP) ceramics were evaluated. High-purity tetragonal ZrO2 powder stabilized with 3 mol.% Y2O3 and La2O3-Rich glass were used as starting powders. Two compositions, ZrO2 containing 5 and 10 wt.% of a La2O3-rich glass were studied in this work. The starting powders were mixed/milled by planetary milling, dried at 90°C for 24 hours, sieved through a 60 mesh screen and uniaxially cold pressed under 80 MPa. The samples were sintered in air at 1200, 1300 and 1400°C for 60min, and at 1450°C for 120min, with heating and cooling rates of 10°C/min. Sintered samples were characterized by relative density, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties, hardness and fracture toughness, were obtained by Vickers indentation method. Dense sintered samples were obtained for all conditions. Samples sintered at 1300°C for 60 min presented the optimal mechanical properties with hardness of 1170 kgf.mm-2 and fracture toughness of 8.3 MPam1/2.

Crosslinking and Mechanical Properties of Liquid Rubber. I. Curative Effect of Aliphatic DIOLS

1979 ◽  
Vol 52 (5) ◽  
pp. 920-948 ◽  
Author(s):  
Yuji Minoura ◽  
Shinzo Yamashita ◽  
Hiroshi Okamoto ◽  
Tadao Matsuo ◽  
Michiaki Izawa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Low Molecular Weight ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Curative Effect ◽  
Polyurethane Elastomers ◽  
X Ray ◽  
Structure Property Relationships ◽  
The Difference

Abstract The structure-property relationships of polyurethane elastomers derived from a liquid hydroxyl-terminated polybutadiene/low molecular weight aliphatic diol/diisocyanate system were studied. The effects of the amount of low molecular weight diol on the mechanical properties of the elastomer were discussed on the basis of the results of stress-strain, swelling, dynamic viscoelasticity, x-ray diffraction, etc. It was found that some particular combinations of low molecular weight diol and diisocyanate specifically affect the properties of elastomers. When the mechanical properties of the elastomers were plotted against the number of methylene carbons in the low molecular weight diol, characteristic zigzag patterns were obtained. These patterns were explained by the difference in the packing and the dependence of the strength of intermolecular hydrogen bonding on whether the number of the methylene carbons was even or odd. This assumption was confirmed by x-ray diffraction.

scholarly journals The Effects of Nanosilica on Mechanical Properties and Fracture Toughness of Geopolymer Cement

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2178
Author(s):  
Cut Rahmawati ◽  
Sri Aprilia ◽  
Taufiq Saidi ◽  
Teuku Budi Aulia ◽  
Agung Efriyo Hadi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Agricultural Waste ◽  
X Ray ◽  
Geopolymer Cement ◽  
Direct Tensile ◽  
Direct Tensile Strength ◽  
Geopolymer Paste

Nanosilica produced from physically-processed white rice husk ash agricultural waste can be incorporated into geopolymer cement-based materials to improve the mechanical and micro performance. This study aimed to investigate the effect of natural nanosilica on the mechanical properties and microstructure of geopolymer cement. It examined the mechanical behavior of geopolymer paste reinforced with 2, 3, and 4 wt% nanosilica. The tests of compressive strength, direct tensile strength, three bending tests, Scanning Electron Microscope-Energy Dispersive X-ray (SEM/EDX), X-ray Diffraction (XRD), and Fourier-transform Infrared Spectroscopy (FTIR) were undertaken to evaluate the effect of nanosilica addition to the geopolymer paste. The addition of 2 wt% nanosilica in the geopolymer paste increased the compressive strength by 22%, flexural strength by 82%, and fracture toughness by 82% but decreased the direct tensile strength by 31%. The microstructure analysis using SEM, XRD, and FTIR showed the formation of calcium alumina-silicate hydrate (C–A–S–H) gel. The SEM images also revealed a compact and cohesive geopolymer matrix, indicating that the mechanical properties of geopolymers with 2 wt% nanosilica were improved. Thus, it is feasible for nanosilica to be used as a binder.

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