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Influence of activation modes on diametral tensile strength of dual-curing resin cements.

Fonseca, Renata Garcia; Santos, Juliana Gomes dos; Adabo, Gelson Luis
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 267-271
ENG
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In metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. The effect of the lack of photoactivation on the strength of these cements has been rarely studied. This study evaluated the influence of activation modes on the diametral tensile strength (DTS) of dual-curing resin cements. Base and catalyst pastes of Panavia F, Variolink II, Scotchbond Resin Cement, Rely X and Enforce were mixed and inserted into cylindrical metal moulds (4 x 2 mm). Cements were either: 1) not exposed to light (chemical activation = self-cured groups) or 2) photoactivated through mylar strips (chemical and photo-activation = dual-cured groups) (n = 10). After a 24 h storage in 37 masculineC distilled water, specimens were subjected to compressive load in a testing machine. A self-curing resin cement (Cement-It) and a zinc phosphate cement served as controls. Comparative analyses were performed: 1) between the activation modes for each dual-curing resin cement, using Students t test; 2) among the self-cured groups of the dual-curing resin cements and the control groups, using one-way ANOVA and Tukeys test (alpha = 0.05). The dual-cured groups of Scotchbond Resin Cement (53.3 MPa), Variolink II (48.4 MPa) and Rely X (51.6 MPa) showed higher DTS than that of self-cured groups (44.6...

Development of the liquid dynamic compaction technique and its application to two high strength aluminum alloys

Lavernia, Enrique J
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 2 v. (336 leaves); 21995825 bytes; 21995582 bytes; application/pdf; application/pdf
ENG
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by Enrique J. Lavernia.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE; Vita.; Bibliography: leaves 312-335.

Hydrogen assisted cracking of high strength steel welds

Gedeon, Steven Anthony
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 2 v. (360 [i.e. 361] leaves); 16081912 bytes; 16081670 bytes; application/pdf; application/pdf
ENG
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by Steven Anthony Gedeon.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987.; Vita.; Bibliography: v. 2, leaves 324-359.

Dispersed-phase transformation toughening in ultrahigh-strength steels

Haidemenopoulos, Gregory N
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 174 leaves; 10968164 bytes; 10967924 bytes; application/pdf; application/pdf
ENG
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by Gregory N. Haidemenopoulos.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1988.; Vita.; Includes bibliographical references.

Grain-refining dispersions and mechanical properties in ultrahigh-strength steels

Gore, Mark John
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 167 leaves; 12123141 bytes; 12122895 bytes; application/pdf; application/pdf
ENG
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by Mark John Gore.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1988.; Vita.; Includes bibliographical references.

Polyelectrolyte multilayers : nanofabricated architectures for bio-interface materials

Mendelsohn, Jonas Daniel, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 135 p.; 14268994 bytes; 14268753 bytes; application/pdf; application/pdf
ENG
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The layer-by-layer process, whereby aqueous solutions of oppositely charged polymers are alternately and repeatedly deposited onto a substrate, has emerged in recent years as a promising approach for creating thin films with nanoscale control of structure, composition, and surface properties. Applications ranging from surface modification to optical and electronic devices have arisen from the versatility of this nanocomposite fabrication technique. The additional ability to assemble into films a wide variety of biological entities, such as enzymes and DNA, has expanded the use of polyelectrolyte multilayers for biosensor and other biomaterials applications. This thesis further explores the rationale of using multilayers as biomaterials, with particularly emphasis on the importance of the underlying molecular architecture. Many of the results presented here concern films assembled from weak polyions, i.e., ones with pH-dependent charge densities, including poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH). Using weak polyions enables the creation of thin films with chemical and structural properties controlled with nanoscale precision by simply adjusting the pH of the polymer solutions. Under certain assembly conditions...

Multiscale mechanical studies of nacre from gastropod mollusk Trochus Nilocitus

Bruet, Benjamin J. F. (Benjamin Jean Fernand), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 83 p.; 4147986 bytes; 4156885 bytes; application/pdf; application/pdf
EN_US
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(cont.) revealed jagged and branched crack fronts at plate interface, tortuous crack paths, non-uniform angles of polygons (suggesting possible intrinsic deformability and displacement/sliding). The technique of nanoindentation was carried out on individual aragonite tablets using a diamond-coated Berkovich probe tip (end-radius of 70 nm, tip angle of 142.3 degrees), at a rate of indentation of 10 [micro]N/s (load controlled), forces from 10 to 1000 [micro]N and indentation depths from 10 to 97 nm. AFM inspection of the indented region showed the existence of extensive plastic deformation within the tablet and suggested that occluded biomacromolecules may play a significant role in the deformation at loads below 100 [micro]N. Using the contact elastic theory, a Young modulus of 112.3 GPa and a hardness of 10.5 GPa were found for an individual platelet. This study shows that a biocomposite principally composed of a poor ceramic (aragonite) can achieve surprisingly good macroscopic mechanical properties thanks to a complex hierarchical structure allowing an extraordinary variety of energy-dissipating mechanisms. Our aim is to continue to formulate multiscale structure-property relationships to eventually aid in the design and advancement of new synthetic biologically inspired lightweight...

Chemomechanics of calcium leaching of cement-based materials at different scales : the role of CH-dissolution and C-S-H degradation on strength and durability performance of materials and structures

Heukamp, Franz H. (Franz Hoyte), 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 380 p.; 16345201 bytes; 16345001 bytes; application/pdf; application/pdf
ENG
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Calcium leaching is a durability threat for cement-based materials employed in critical infrastructures, such as Nuclear Waste Storage Systems. This thesis presents a comprehensive study of the material and structural consequences of calcium leaching on the strength and deformation behavior of cementitious materials. Starting from a three-level microstructural division of the heterogeneous microstructure of cement-based materials, a series of experimental and theoretical investigations is conducted leading to the development of a novel constitutive model and model-based simulations of the long-term mechanical performance of concrete structures subjected to calcium leaching. A chemically accelerated leaching device is developed using an ammonium nitrate solution to obtain asymptotically leached specimens in short times. An acceleration rate of 300 compared to natural leaching is obtained. The strength domain of leached cement pastes and mortars is evaluated through triaxial compression tests and uniaxial tension tests, revealing an important strength loss and an increased pressure sensitivity of the materials at failure, associated with leaching. A micromechanical approach for the homogenization of the elastic properties and the strength properties based on the three microstructural levels is developed. These developments allow estimating the relations between the microstructural changes and poroelastic properties including Biot-coefficient and Biot-modulus. In addition...

Synthesis and characterization of nanocrystalline alloys in the binary Ni-Co system/

Wu, Bruce Y. C., 1980
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 leaves; 3862057 bytes; 3860069 bytes; application/pdf; application/pdf
ENG
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Nanocrystalline Ni-Co alloys were synthesized using pulsed electrodeposition from a Watts-type bath, and the various plating parameters were systematically varied to examine their effect on the composition, quality, and structure of the resulting deposits. Increasing the pH of the plating bath and/or the average plating current density increased the Ni content of the deposits, but both of these parameters exhibited rather narrow processing windows for the preparation of high-quality deposits. The addition of saccharin during plating was observed both to reduce the crystallographic texture of the Ni-Co alloys and to refine the grain structure. Owing to the low stacking fault energy of Co, many of the alloy deposits exhibited a large density of nanoscale twins. The unique dual-scale grain and nano-twin structure found here caused apparent discrepancies in the grain size measured by XRD and by other microscopy techniques, and also resulted in unique trends in hardness. This thesis lays the groundwork for future tailoring of nanostructured alloys to explore how twins and stacking faults influence their strength and ductility.; by Bruce Y.C. Wu.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering...

Experimental investigation of tearing fracture in sheets under quasi-static loading

Roach, Michael L. (Michael Louis)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 162 leaves; 7587659 bytes; 7594467 bytes; application/pdf; application/pdf
ENG
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Although there has been interest in the behavior of metal plates under blast and projectile loading for many years, definitive open-source analysis has only been recently forthcoming. This analysis is most often in the form of scaled recreations of the dynamic blast event, or "live fire" tests. New developments in methods of recreating blast and projectile induced plate failure using a quasi-static approach provide possible, accurate, alternatives to the cumbersome and expensive live fire test. This research endeavors to develop an accurate, quasi-static method of recreating the petalling phase of blast and projectile failure in metal sheets, based on a modified trousers- type test. By using the trousers-type fracture test the overall plastic bending kinematics of the fractured petal is preserved, as well as the mixed mode (mode one and mode three) fracture. Through analytical and qualitative analysis, a testing apparatus to generate this trousers-type, plastic bending and mixed mode fracture was designed and machined. The apparatus was then used to test thin steel sheets of varying thickness (0.419 and 0.724mm) in order to validate the quasi-static method of recreating the petalling phase through a comparison with analytically derived results.; by Michael L. Roach.; Thesis (Nav. E.)--Massachusetts Institute of Technology...

Triptycene side unit effects on compressive yield strength in polycarbonates

Fraser, Douglas (Douglas H.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 25 leaves; 1156183 bytes; 1154492 bytes; application/pdf; application/pdf
ENG
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Polycarbonates have long been studied for their excellent mechanical toughness. Adding side units to polycarbonate could increase physical properties of the polymer. The role of triptycene in polycarbonate was studied by adding a low concentration of triptycene-containing polymer chains, and using compression testing. The triptycene polycarbonate was a blend created from two separate products. Differential Scanning Calorimetry was used to determine if the samples had phase separated. Thermal degradation of the samples was checked for using Thermogravimetric Analysis. Results indicated that triptycene-containing polycarbonates had higher compressive yield strengths than non-triptycene polycarbonates. The polymers were stronger due to the interlocking mechanism and the steric hindrance of the triptycene units. The design of strengthening polymers by adding triptycene units could prove useful to improve high performing polymers, or to give low molecular weight polymers more stability.; by Douglas Fraser.; Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.; Includes bibliographical references (leaf 25).

Mechanical characterization and in vivo operation of an implantable drug delivery MEMS device

Li, Yawen, 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 137 p.
ENG
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The goal of this thesis was to advance an implantable drug delivery MEMS (MicroElectroMechanical Systems) device developed in our laboratory. This device was designed to locally deliver multiple substances in complex release profiles in order to maximize the effectiveness of drug therapies. It consists of an array of microreservoirs etched into a silicon substrate. Different types and dosages of drugs can be contained in these reservoirs capped by thin gold membranes. The drug release is achieved by the application of a small anodic potential on the gold membrane in a chloride containing medium (such as the body fluid). The gold membrane will corrode and disintegrate so that the drug contained within the reservoir is free to diffuse into the surrounding medium. Previous researchers have demonstrated in vitro and in vivo release of tracer molecules as well as a radiolabled chemotherapeutic agent (carmustine, or BCNU) from the device. However, systematic characterization of the mechanical and electrochemical behavior of gold membranes on the drug delivery device was necessary in order to achieve more reliable device performance and to demonstrate efficacy of BCNU delivered from the MEMS device against an experimental tumor model. A bulge test apparatus was constructed to characterize the mechanical properties of gold membranes. Uniform pressure was applied from underneath the gold membrane and the membrane deflection was measured using optical interferometry. Analyzing the deflection and pressure data allowed extraction of the elastic modulus and residual stress of the gold membrane.; (cont.) Gold membranes with in-plane sizes ranging from 20 to 200pim showed lower modulus (126-168 GPa) than bulk (111) single crystal gold (189 GPa). But their yield strength (317-351 MPa) was higher than the bulk value. An in situ experimental setup was constructed to observe the electrochemical disintegration process of the gold membranes. Real time images recorded from a CCD camera showed non-uniform corrosion occurring first around the membrane edges. Bulge tests on the corroded membranes indicated a gradual loss of mechanical integrity of the gold membranes due to corrosion. The gold membrane disintegration probably occurred by a combination of membrane thinning through active dissolution and accumulation of plastic deformation due to the transient formation of a passive film on top of the gold membrane in each voltammetry cycle. Dense gold membranes with reproducible opening behavior are critical to the success of large scale in vivo studies and future commercial applications. Defects in the gold membranes led to premature leakage of BCNU...

Block copolymer-templated iron oxide nanoparticles for bimodal growth of multi-walled carbon nanotubes

Yazzie, Kyle E
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 74 leaves
ENG
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Since their discovery carbon nanotubes (CNTs) have sparked great interest due to their exceptional mechanical, electrical, and thermal properties. These properties make carbon nanotubes desirable for numerous applications including: nanoelectronics, high-strength composites, energy storage, superhydrophobic surfaces, sensors, and biomaterial interfaces. Bulk synthesis of carbon nanotubes with controlled physical features, i.e. length, diameter, multiwalled vs. single walled, carbon nanotube chirality, etc. is necessary to make full use of carbon nanotubes exceptional properties in commercial aspects. Typical carbon nanotube synthesis processes use chemical vapor deposition (CVD), arc-discharge, and laser ablation. Synthesizing carbon nanotubes via CVD typically involves depositing a thin metal film on a silicon substrate, and heating the substrate so that the thin metal film dewets and forms metallic nanoparticles. A hydrocarbon gas is then flowed over the nanoparticles to initiate carbon nanotube growth. Though these thin metal film catalysts are easy to prepare, they offer poor control over nanoparticle diameters and areal density. It has been shown that physical properties of carbon nanotubes, such as diameter and uniformity of growth...

Novel approaches to low temperature transient liquid phase bonding in the In-Sn/Cu and In-Sn-Bi/Cu systems

Fischer, David S., Ph. D. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 114 leaves
ENG
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A fluxless low temperature transient liquid phase (LTTLP) bonding process was studied as a method of producing Cu/Cu joints below 125°C and 75°C using interlayer alloys from the In-Sn and In-Sn-Bi systems. Using thermodynamic models, three different compositions (wt. %) of base alloys were chosen to accomplish this task: 50In-43.6Sn-6.4Bi (Tm = 110°C) and eutectic 50.9In-49.1Sn (Tm = 120°C) alloys were used for bonding at 125°C and a eutectic 48.3In-15.6Sn-36.1Bi (Tm = 60°C) alloy was used for bonding at 75°C. In addition, novel approaches to TLP bonding, including the addition of base material to the interlayer alloy and application of an electroless Ni diffusion barrier layer, were employed in an attempt to optimize this joining method. The LTTLP processes were assessed based on their abilities to produce joints with minimal thickness, high reflow temperatures, and good mechanical properties at room/elevated temperatures. It was found that interlayer alloys containing higher Bi contents produced the thinnest joints, with the 48.3In-15.6Sn-36.1Bi alloy producing joints on the order of 10 gm. Increases in nominal Cu composition of the interlayer alloy tended to form larger joints. Application of the Ni layer was observed to decrease the growth rate of the eutectic In-Sn joints made with 5 wt % Cu additions. Shear tests were performed on the joints at room (25°C) and operating (service) temperatures (100°C). Most of the TLP joints had room temperature shear strengths around 13...

Supplement to mechanical properties of plastic laminates

Werren, Fred; Forest Products Laboratory (U.S.); University of Wisconsin
Fonte: United States Dept. of Agriculture, Forest Service, Forest Products Laboratory; United States Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis ) Publicador: United States Dept. of Agriculture, Forest Service, Forest Products Laboratory; United States Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
Tipo: Artigo de Revista Científica Formato: 5, [17] p. : ill. ; 26 cm.
Publicado em // ENGLISH
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(Additional Physical Form) Also available in electronic format.; (Statement of Responsibility) by Fred Werren.; Caption title.; "Original report dated 1953"--Cover.; "Information reviewed and reaffirmed 1960"--Cover.; "In cooperation with the University of Wisconsin"--Cover.

Fundamental studies of polyelectrolyte multilayer films : optical, mechanical, and lithographic property control; Fundamental studies of PEM films : optical, mechanical, and lithographic property control

Nolte, Adam John
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 225 p.
ENG
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Polyelectrolyte multilayers (PEMs) are a versatile type of thin film that is created via layer-by-layer assembly of positively and negatively charged polymers from aqueous solutions. Precise control of the PEM thickness, chemical functionality, and molecular architecture is made possible by changing the polyelectrolytes and assembly conditions during film growth, allowing films to be designed with properties suitable for a given application. This thesis elucidates the intra-film structure and interactions of PEMs through the use of optical, mechanical, and chemical techniques. PEM rugate filters, wherein the refractive index varies through the depth of the film in a continuous, periodic fashion, were constructed by confining silver nanoparticle growth to layers of nanometer-scale thickness. The ability to construct such structures is shown to be dependent on the ability to precisely control the concentration of metal-binding carboxylic acid groups throughout the depth of the film. Software to enable the computation design and optical simulation of these and similar structures was developed.; (cont.) A buckling instability technique was used to probe the Young's modulus of PEM assemblies as a function of polyelectrolyte type, assembly pH...

Systematic analysis of the crystal structure, chemical ordering, and microstructure of Ni-Mn-Ga ferromagnetic shape memory alloys

Richard, Marc Louis
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 147 p.; 29332225 bytes; 29334542 bytes; application/pdf; application/pdf
ENG
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Ni-n-Ga based ferromagnetic shape-memory alloys (FSMAs) have shown great promise as an active material that yields a large output strain over a range of actuation frequencies. The maximum strain has been reported to be 6% in the tetragonal martensitic phase and up to 10% in the orthorhombic phase. There has been a large body of work exploring the engineering properties of these alloys but less extensive work in the understanding of the underlying structure and its connection to the material properties. This is particularly true for the off-stoichiometry compositions that are of most practical interest. The crystal structure of Ni-Mn-Ga ferromagnetic shape-memory alloys is extremely sensitive to composition. Several martensitic structures including tetragonal (5-layer), orthorhombic (7-layer) and non-modulated tetragonal have been identified. A systematic exploration of the composition-structure relationship has been performed using x-ray diffraction on samples taken from several single crystals with different compositions. A room temperature phase diagram has been constructed delineating the fields where the tetragonal and orthorhombic martensites are found.; (cont.) Temperature-dependent magnetic and x-ray measurements have revealed markedly different transformation behavior in the tetragonal and orthorhombic materials. The orthorhombic material shows a much larger difference between the martensite start and finish temperatures as compared to tetragonal martensite. The observed difference in transformation behavior has been shown not to be related to composition inhomogeneity or the presence of intermediate martensitic phases. A thermodynamic model is proposed to explain the differences in the transition behavior by including strain energy effects in the two martensite phases that may arise during the transformation. Single-crystal and powder neutron diffraction have been employed to study for the first time the chemical ordering in the austenite and martensite phases in off- stoichiometric alloy compositions. A comparison of compositions with close to 50 at% 3Ni and those further from stoichiometry revealed the need for a more complex model for the site occupancy in alloys with a significant excess or deficiency of Ni.; (cont.) The microstructure of several different Ni-Mn-Ga alloys was analyzed using transmission electron microscopy providing new microstructural data that has not been shown elsewhere. The superstructures of the different compositions has been confirmed...

The effect of the packing density on the indentation hardness of cohesive-frictional porous materials

Cariou, Sophie, S.M. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 192 p.; 30577924 bytes; 30577274 bytes; application/pdf; application/pdf
ENG
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Natural composites in general and sedimentary rocks in particular are highly heterogeneous materials which defy a straightforward implementation of the materials science paradigm of microstructure-properties-performance correlation. The application of nanoindentation to natural composites has provided the geomechanics community with a new versatile tool to test in situ phase properties and structures of geomaterials that cannot be recapitulated ex situ in bulk form. But it requires a rigorous indentation analysis to translate indentation data into meaningful mechanical properties. The development and implementation of such an indentation analysis for the strength properties of cohesive-frictional porous materials is the focus of this thesis. We report the development and implementation of a multi-scale indentation analysis based on limit analysis, which makes it possible to infer from an experimental hardness value and the solid's packing density the strength properties of the cohesive-frictional porous material.; (cont.) Making use of most recent advances in non-linear strength homogenization theory, we implement a homogenized cohesive Cam-Clay type elliptical strength criterion which takes into account the strength properties of the constituents (cohesion and friction)...

Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

Al-Makramani,Bandar Mohammed Abdullah; Razak,Abdul Aziz Abdul; Abu-Hassan,Mohamed Ibrahim
Fonte: Faculdade De Odontologia De Bauru - USP Publicador: Faculdade De Odontologia De Bauru - USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
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Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. OBJECTIVES: The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. MATERIAL AND METHODS: Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. RESULTS: The mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows...

Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

Al-Makramani, Bandar Mohammed Abdullah; Razak, Abdul Aziz Abdul; Abu-Hassan, Mohamed Ibrahim
Fonte: Universidade de São Paulo. Faculdade de Odontologia de Bauru Publicador: Universidade de São Paulo. Faculdade de Odontologia de Bauru
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 01/12/2010 ENG
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Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. OBJECTIVES: The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. MATERIAL AND METHODS: Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. RESULTS: The mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows...