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https://www.readbyqxmd.com/read/29151459/the-ball-on-disk-cyclic-wear-of-cad-cam-machinable-dental-composite-and-ceramic-materials
#1
Kazuyuki Handa, Natsuko Murakami, Toshiki Yamazaki, Hidekazu Takahashi, Noriyuki Wakabayashi
The purpose of this study was to investigate the wear volume and the principal strain of machinable dental composite and ceramics in simulated mastication. A ball-on-disk wear test was performed for 3,000 cycles in water, using nine ball/disk combinations of three commercial CAD/CAM materials: feldspathic, lithium disilicate glass ceramics, and a highly loaded composite material (n = 7 for each combination). The wear volume was optically measured using a digital scanner and analyzed for statistical differences based on the materials (α = 0...
November 17, 2017: Journal of Oral Science
https://www.readbyqxmd.com/read/29144007/analysis-of-surface-roughness-fracture-toughness-and-weibull-characteristics-of-different-framework-veneer-dental-ceramic-assemblies-after-grinding-polishing-and-glazing
#2
Guillermo Pradíes, Laura Godoy-Ruiz, Mutlu Özcan, Isabel Moreno-Hay, Francisco Martínez-Rus
PURPOSE: To compare the surface roughness and biaxial flexural strength of dental ceramics obtained after chairside surface modification by mechanical polishing procedures, versus laboratory reglazing. MATERIALS AND METHODS: Discs (16 × 1.5 ± 1.6 mm) (N = 90) of various framework-veneering combinations were fabricated: D/FC: lithium disilicate/feldspathic ceramic; Z/AL: zirconium dioxide/aluminous ceramic; N/FC: noble alloy/feldspathic ceramic; N/FF: noble alloy feldspathic with fluorapatite; B/FC: base alloy/feldspathic ceramic; B/FF: base alloy/feldspathic ceramic with fluorapatite...
November 16, 2017: Journal of Prosthodontics: Official Journal of the American College of Prosthodontists
https://www.readbyqxmd.com/read/29134692/water-rich-biomimetic-composites-with-abiotic-self-organizing-nanofiber-network
#3
Lizhi Xu, Xueli Zhao, Chuanlai Xu, Nicholas A Kotov
Load-bearing soft tissues, e.g., cartilage, ligaments, and blood vessels, are made predominantly from water (65-90%) which is essential for nutrient transport to cells. Yet, they display amazing stiffness, toughness, strength, and deformability attributed to the reconfigurable 3D network from stiff collagen nanofibers and flexible proteoglycans. Existing hydrogels and composites partially achieve some of the mechanical properties of natural soft tissues, but at the expense of water content. Concurrently, water-rich biomedical polymers are elastic but weak...
November 14, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29123105/total-morphosynthesis-of-biomimetic-prismatic-type-caco3-thin-films
#4
Chuanlian Xiao, Ming Li, Bingjun Wang, Ming-Feng Liu, Changyu Shao, Haihua Pan, Yong Lu, Bin-Bin Xu, Siwei Li, Da Zhan, Yuan Jiang, Ruikang Tang, Xiang Yang Liu, Helmut Cölfen
Biomimetic mineralization can lead to advanced crystalline composites with common chemicals under ambient conditions. An exceptional example is biomimetic nacre with its superior fracture toughness. The synthesis of the prismatic layer with stiffness and wear resistance nonetheless remains an elusive goal. Herein, we apply a biomimetic mineralization method to grow prismatic-type CaCO3 thin films, mimicking their biogenic counterparts found in mollusk shells with a three-step pathway: coating a polymer substrate, deposition of a granular transition layer, and mineralization of a prismatic overlayer...
November 9, 2017: Nature Communications
https://www.readbyqxmd.com/read/29119950/bio-inspired-composites-with-functionally-graded-platelets-exhibit-enhanced-stiffness
#5
Sanjay Tapse, Anup S
Unidirectional composites inspired from biological materials such as nacre, are composed of stiff platelets arranged in a staggered manner within a soft matrix. Elaborate analyses have been conducted on the aforementioned composites and they are found to have excellent mechanical properties like stiffness, strength and fracture toughness. The superior properties exhibited by these composites have been proved to be the result of its unique structure. An emerging development in the field of composite structures is Functionally Graded Composites(FGC), whose properties vary spatially and possess enhanced thermo-mechanical properties...
November 9, 2017: Bioinspiration & Biomimetics
https://www.readbyqxmd.com/read/29116135/novel-electrical-and-mechanical-characteristics-of-composites-composed-of-electrically-conducting-ni-cr-alloy-particles-in-non-conducting-soda-lime-glass
#6
Yoshiharu Waku, Teruyuki Yamashita, Hiroyuki Kitagawa, Masahiro Yoshinobu, Hiromichi Katsuyama, Daiki Hamano, Shinji Harui
The bulk resistivity of Ni-Cr alloys is inherently constant. Therefore, it is necessary to regulate the cross-section and length of Ni-Cr alloys to achieve the desired electrical resistance. Here, we describe a composite, comprising a soda-lime glass matrix and disk-like Ni-Cr alloy particles, that has variable bulk resistivity. The bulk resistivity of the composite can be controlled accurately by adjusting the volume fraction (30-80 vol% Ni-Cr alloy) and aspect ratio of the particles. Furthermore, the composite's strength and fracture toughness are both improved by microdispersion of the disk-like Ni-Cr alloy particles...
November 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29116133/atomistic-representation-of-anomalies-in-the-failure-behaviour-of-nanocrystalline-silicene
#7
Tawfiqur Rakib, Sourav Saha, Mohammad Motalab, Satyajit Mojumder, Md Mahbubul Islam
Silicene, a 2D analogue of graphene, has spurred a tremendous research interest in the scientific community for its unique properties essential for next-generation electronic devices. In this work, for the first time, we present a molecular dynamics (MD) investigation to determine the fracture strength and toughness of nanocrystalline silicene (nc-silicene) sheet of varying grain sizes and pre-existing cracks at room temperature. Our results suggest a transition from an inverse pseudo Hall-Petch to a pseudo Hall-Petch behaviour in nc-silicene at a critical grain size of 17...
November 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29113700/high-performance-dental-resin-composites-with-hydrolytically-stable-monomers
#8
Xiaohong Wang, George Huyang, Sri Vikram Palagummi, Xiaohui Liu, Drago Skrtic, Carlos Beauchamp, Rafael Bowen, Jirun Sun
OBJECTIVE: The objectives of this project were to: 1) develop strong and durable dental resin composites by employing new monomers that are hydrolytically stable, and 2) demonstrate that resin composites based on these monomers perform superiorly to the traditional bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) composites under testing conditions relevant to clinical applications. METHODS: New resins comprising hydrolytically stable, ether-based monomer, i...
November 4, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/29112917/influence-of-minor-combined-addition-of-cr-and-pr-on-microstructure-mechanical-properties-and-corrosion-behaviors-of-an-ultrahigh-strength-al-zn-mg-cu-zr-alloy
#9
Ming Wang, Lanping Huang, Kanghua Chen, Wensheng Liu
This work focuses on controlling grain boundary structure in an ultra-high strength Al-8.6Zn-2.5Mg-2.2Cu-0.16Zr (wt.%) alloy by the combined addition of trace Cr (0.1wt.%) and Pr (0.14wt.%), and evaluating mechanical properties and localized corrosion behaviors of the alloy in the peak aged condition. The introduction of trace Cr and Pr leads to the formation of nanoscale Cr, Pr-containing Al3Zr and Zr-containing PrCr2Al20 dispersoids which can obviously inhibit the recrystallization and sub-grain growth of the super-high strength Al-Zn-Mg-Cu alloys, and retain the deformation-recovery microstructure dominated by low-angle grain boundaries...
October 26, 2017: Micron: the International Research and Review Journal for Microscopy
https://www.readbyqxmd.com/read/29111203/the-effect-of-microcracking-in-the-peritubular-dentin-on-the-fracture-of-dentin
#10
Bingbing An, H Daniel Wagner
Dentin is a biocomposite possessing elegant hierarchical structure, which allows it to resist fracture effectively. Despite the considerable efforts to unravel the peculiar fracture behavior of dentin, the effect of microstructural features on the fracture process is largely unknown. In this study, we explore the interaction between the primary crack with crack tip located in intertubular dentin (ITD) and microcracking of peritubular dentin (PTD) ahead of the primary crack. A micromechanical model accounting for the unique composite structure of dentin is developed, and computational simulations are performed...
October 25, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/29107057/rapid-fabrication-of-microneedles-using-magnetorheological-drawing-lithography
#11
Zhipeng Chen, Lei Ren, Jiyu Li, Lebin Yao, Yan Chen, Bin Liu, Lelun Jiang
Microneedles are micron-sized needles that are widely applied in biomedical fields owing to their painless, minimally invasive, and convenient operation. However, most microneedle fabrication approaches are costly, time consuming, involve multiple steps, and require expensive equipment. In this study, we present a novel magnetorheological drawing lithography (MRDL) method to efficiently fabricate microneedle, bio-inspired microneedle, and molding-free microneedle array. With the assistance of an external magnetic field, the 3D structure of a microneedle can be directly drawn from a droplet of curable magnetorheological fluid...
October 26, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/29104278/use-of-nanoparticles-for-enhancing-the-interlaminar-properties-of-fiber-reinforced-composites-and-adhesively-bonded-joints-a-review
#12
REVIEW
Davide De Cicco, Zohreh Asaee, Farid Taheri
This review paper aims at reporting some of the notable works carried out concerning the use of nanoparticles (NPs) as a means of improving the resistance of fiber-reinforced polymer composite materials (FRPs) and adhesively bonded joints (ABJs) to delamination initiation and propagation. Applications of various nanoparticles, such as carbon-based, ceramic-based and mineral-based are discussed. The main properties that have been considered for improving the delamination and fatigue resistance of FRPs are the interlaminar shear strength, fracture toughness, and fracture energy...
November 1, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29098851/micro-and-macromechanical-properties-of-thermoelectric-lead-chalcogenides
#13
Guodong Li, Umut Aydemir, Bo Duan, Matthias T Agne, Hongtao Wang, Max Wood, Qingjie Zhang, Pengcheng Zhai, William A Goddard, G Jeffrey Snyder
Both n- and p-type lead telluride (PbTe)-based thermoelectric (TE) materials display high TE efficiency, but the low fracture strength may limit their commercial applications. To find ways to improve these macroscopic mechanical properties, we report here the ideal strength and deformation mechanism of PbTe using density functional theory calculations. This provides structure-property relationships at the atomic scale that can be applied to estimate macroscopic mechanical properties such as fracture toughness...
November 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29094137/asynchronous-cracking-with-dissimilar-paths-in-multilayer-graphene
#14
Bongkyun Jang, Byungwoon Kim, Jae-Hyun Kim, Hak-Joo Lee, Takashi Sumigawa, Takayuki Kitamura
Multilayer graphene consists of a stack of single-atomic-thick monolayer graphene sheets bound with π-π interactions and is a fascinating model material opening up a new field of fracture mechanics. In this study, fracture behavior of single-crystalline multilayer graphene was investigated using an in situ mode I fracture test under a scanning electron microscope, and abnormal crack propagation in multilayer graphene was identified for the first time. The fracture toughness of graphene was determined from the measured load-displacement curves and the realistic finite element modelling of specimen geometries...
November 16, 2017: Nanoscale
https://www.readbyqxmd.com/read/29084171/simulation-of-intergranular-ductile-cracking-in-%C3%AE-titanium-alloys-based-on-a-micro-mechanical-damage-model
#15
Huan Li, Jinshan Li, Bin Tang, Jiangkun Fan, Huang Yuan
The intergranular crack propagation of the lamellar structure β titanium alloys is investigated by using a modified Gurson-type damage model. The representative microstructure of the lamellar alloy, which consists of the soft α phase layer surrounding the hard grain interiors, is generated based on an advanced Voronoi algorithm. Both the normal fracture due to void growth and the shear fracture associated with void shearing are considered for the grain boundary α layer. The individual phase properties are determined according to the experimental nanoindentation result and the macroscopic stress-strain curve from a uni-axial tensile test...
October 30, 2017: Materials
https://www.readbyqxmd.com/read/29081449/physicochemical-properties-of-discontinuous-s2-glass-fiber-reinforced-resin-composite
#16
Qiting Huang, Wei Qin, Sufyan Garoushi, Jingwei He, Zhengmei Lin, Fang Liu, Pekka K Vallittu, Lippo V J Lassila
The objective of this study was to investigate several physicochemical properties of an experimental discontinuous S2-glass fiberreinforced resin composite. The experimental composite was prepared by mixing 10 wt% of discontinuous S2-glass fibers with 27.5 wt% of resin matrix and 62.5 wt% of particulate fillers. Flexural strength (FS) and modulus (FM), fracture toughness (FT), work of fracture (WOF), double bond conversion (DC), Vickers hardness, volume shrinkage (VS) and fiber length distribution were determined...
October 27, 2017: Dental Materials Journal
https://www.readbyqxmd.com/read/29062036/3d-printing-bioinspired-ceramic-composites
#17
Ezra Feilden, Claudio Ferraro, Qinghua Zhang, Esther García-Tuñón, Eleonora D'Elia, Finn Giuliani, Luc Vandeperre, Eduardo Saiz
Natural structural materials like bone and shell have complex, hierarchical architectures designed to control crack propagation and fracture. In modern composites there is a critical trade-off between strength and toughness. Natural structures provide blueprints to overcome this, however this approach introduces another trade-off between fine structural manipulation and manufacturing complex shapes in practical sizes and times. Here we show that robocasting can be used to build ceramic-based composite parts with a range of geometries, possessing microstructures unattainable by other production technologies...
October 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29053320/interplay-between-process-zone-and-material-heterogeneities-for-dynamic-cracks
#18
Fabian Barras, Philippe H Geubelle, Jean-François Molinari
Using an elastodynamic boundary integral formulation coupled with a cohesive model, we study the problem of a dynamic rupture front propagating along an heterogeneous plane. We show that small-scale heterogeneities facilitate the supershear transition of a mode-II crack. The elastic pulses radiated during front accelerations explain how microscopic variations of fracture toughness change the macroscopic rupture dynamics. Perturbations of dynamic fronts are then systematically studied with different microstructures and loading conditions...
October 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29053258/parrotfish-teeth-stiff-biominerals-whose-microstructure-makes-them-tough-and-abrasion-resistant-to-bite-stony-corals
#19
Matthew A Marcus, Shahrouz Amini, Cayla A Stifler, Chang-Yu Sun, Nobumichi Tamura, Hans A Bechtel, Dilworth Y Parkinson, Harold S Barnard, Xiyue X X Zhang, J Q Isaiah Chua, Ali Miserez, Pupa U P A Gilbert
Parrotfish (Scaridae) feed by biting stony corals. To investigate how their teeth endure the associated contact stresses, we examine the chemical composition, nano- and microscale structure, and the mechanical properties of the steephead parrotfish Chlorurus microrhinos tooth. Its enameloid is a fluorapatite (Ca5(PO4)3F) biomineral with outstanding mechanical characteristics: the mean elastic modulus is 124 GPa, and the mean hardness near the biting surface is 7.3 GPa, making this one of the stiffest and hardest biominerals measured; the mean indentation yield strength is above 6 GPa, and the mean fracture toughness is ∼2...
November 14, 2017: ACS Nano
https://www.readbyqxmd.com/read/29048345/enhancement-of-fracture-toughness-of-epoxy-nanocomposites-by-combining-nanotubes-and-nanosheets-as-fillers
#20
Nadiim Domun, Keith R Paton, Homayoun Hadavinia, Toby Sainsbury, Tao Zhang, Hibaaq Mohamud
In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, GIC, by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS) were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71...
October 19, 2017: Materials
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