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Materials, Volume 10, Issue 10 (October 2017)

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Cover Story (view full-size image) Powder-bed-fusion additive manufactured (PBFAM) parts exhibit a rough surface that has a [...] Read more.
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Open AccessFeature PaperArticle Industrial-Graded Epoxy Nanocomposites with Mechanically Dispersed Multi-Walled Carbon Nanotubes: Static and Damping Properties
Materials 2017, 10(10), 1222; https://doi.org/10.3390/ma10101222
Received: 16 August 2017 / Revised: 21 September 2017 / Accepted: 8 October 2017 / Published: 24 October 2017
Cited by 1 | PDF Full-text (2097 KB) | HTML Full-text | XML Full-text
Abstract
The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing
[...] Read more.
The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young’s modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices. Full article
(This article belongs to the Special Issue Improving Performance of Nanocomposite Materials)
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Open AccessFeature PaperReview On the Hole Injection for III-Nitride Based Deep Ultraviolet Light-Emitting Diodes
Materials 2017, 10(10), 1221; https://doi.org/10.3390/ma10101221
Received: 5 September 2017 / Revised: 7 October 2017 / Accepted: 11 October 2017 / Published: 24 October 2017
Cited by 2 | PDF Full-text (2532 KB) | HTML Full-text | XML Full-text
Abstract
The hole injection is one of the bottlenecks that strongly hinder the quantum efficiency and the optical power for deep ultraviolet light-emitting diodes (DUV LEDs) with the emission wavelength smaller than 360 nm. The hole injection efficiency for DUV LEDs is co-affected by
[...] Read more.
The hole injection is one of the bottlenecks that strongly hinder the quantum efficiency and the optical power for deep ultraviolet light-emitting diodes (DUV LEDs) with the emission wavelength smaller than 360 nm. The hole injection efficiency for DUV LEDs is co-affected by the p-type ohmic contact, the p-type hole injection layer, the p-type electron blocking layer and the multiple quantum wells. In this report, we review a large diversity of advances that are currently adopted to increase the hole injection efficiency for DUV LEDs. Moreover, by disclosing the underlying device physics, the design strategies that we can follow have also been suggested to improve the hole injection for DUV LEDs. Full article
(This article belongs to the Special Issue Wide Bandgap Semiconductors: Growth, Properties and Applications)
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Open AccessArticle Effect of Wafer Level Underfill on the Microbump Reliability of Ultrathin-Chip Stacking Type 3D-IC Assembly during Thermal Cycling Tests
Materials 2017, 10(10), 1220; https://doi.org/10.3390/ma10101220
Received: 28 August 2017 / Revised: 19 October 2017 / Accepted: 23 October 2017 / Published: 24 October 2017
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Abstract
The microbump (μ-bump) reliability of 3D integrated circuit (3D-IC) packaging must be enhanced, in consideration of the multi-chip assembly, during temperature cycling tests (TCT). This research proposes vehicle fabrications, experimental implements, and a nonlinear finite element analysis to systematically investigate the assembled packaging
[...] Read more.
The microbump (μ-bump) reliability of 3D integrated circuit (3D-IC) packaging must be enhanced, in consideration of the multi-chip assembly, during temperature cycling tests (TCT). This research proposes vehicle fabrications, experimental implements, and a nonlinear finite element analysis to systematically investigate the assembled packaging architecture that stacks four thin chips through the wafer level underfill (WLUF) process. The assembly of μ-bump interconnects by daisy chain design shows good quality. Results of both TCT data and the simulation indicate that μ-bumps with residual SnAg solders can reach more than 1200 fatigue life cycles. Moreover, several important design factors in the present 3D-IC package influence μ-bump reliability. Analytical results show that the μ-bump’s thermo-mechanical reliability can be improved by setting proper chip thickness, along with a WLUF that has a low elastic modulus and a small coefficient of thermal expansion. Full article
(This article belongs to the Special Issue Selected Papers from IMETI2016)
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Open AccessReview Aspects of Solvent Chemistry for Calcium Hydroxide Medicaments
Materials 2017, 10(10), 1219; https://doi.org/10.3390/ma10101219
Received: 13 September 2017 / Revised: 17 October 2017 / Accepted: 17 October 2017 / Published: 23 October 2017
PDF Full-text (421 KB) | HTML Full-text | XML Full-text
Abstract
Calcium hydroxide pastes have been used in endodontics since 1947. Most current calcium hydroxide endodontic pastes use water as the vehicle, which limits the dissolution of calcium hydroxide that can be achieved and, thereby, the maximum pH that can be achieved within the
[...] Read more.
Calcium hydroxide pastes have been used in endodontics since 1947. Most current calcium hydroxide endodontic pastes use water as the vehicle, which limits the dissolution of calcium hydroxide that can be achieved and, thereby, the maximum pH that can be achieved within the root canal system. Using polyethylene glycol as a solvent, rather than water, can achieve an increase in hydroxyl ions release compared to water or saline. By adopting non-aqueous solvents such as the polyethylene glycols (PEG), greater dissolution and faster hydroxyl ion release can be achieved, leading to enhanced antimicrobial actions, and other improvements in performance and biocompatibility. Full article
(This article belongs to the Special Issue Dental Biomaterials 2017)
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Open AccessArticle Fabrication of Composite Filaments with High Dielectric Permittivity for Fused Deposition 3D Printing
Materials 2017, 10(10), 1218; https://doi.org/10.3390/ma10101218
Received: 30 September 2017 / Revised: 18 October 2017 / Accepted: 20 October 2017 / Published: 23 October 2017
Cited by 4 | PDF Full-text (16206 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Additive manufacturing of complex structures with spatially varying electromagnetic properties can enable new applications in high-technology sectors such as communications and sensors. This work presents the fabrication method as well as microstructural and dielectric characterization of bespoke composite filaments for fused deposition modeling
[...] Read more.
Additive manufacturing of complex structures with spatially varying electromagnetic properties can enable new applications in high-technology sectors such as communications and sensors. This work presents the fabrication method as well as microstructural and dielectric characterization of bespoke composite filaments for fused deposition modeling (FDM) 3D printing of microwave devices with a high relative dielectric permittivity ϵ = 11 in the GHz frequency range. The filament is composed of 32 vol % of ferroelectric barium titanate (BaTiO 3 ) micro-particles in a polymeric acrylonitrile butadiene styrene (ABS) matrix. An ionic organic ester surfactant was added during formulation to enhance the compatibility between the polymer and the BaTiO 3 . To promote reproducible and robust printability of the fabricated filament, and to promote plasticity, dibutyl phthalate was additionally used. The combined effect of 1 wt % surfactant and 5 wt % plasticizer resulted in a uniform, many hundreds of meters, continuous filament of commercial quality capable of many hours of uninterrupted 3D printing. We demonstrate the feasibility of using the high dielectric constant filament for 3D printing through the fabrication of a range of optical devices. The approach herein may be used as a guide for the successful fabrication of many types of composite filament with varying functions for a broad range of applications. Full article
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Open AccessArticle A Constitutive Relationship for Gravelly Soil Considering Fine Particle Suffusion
Materials 2017, 10(10), 1217; https://doi.org/10.3390/ma10101217
Received: 18 September 2017 / Revised: 13 October 2017 / Accepted: 19 October 2017 / Published: 23 October 2017
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Abstract
Suffusion erosion may occur in sandy gravel dam foundations that use suspended cutoff walls. This erosion causes a loss of fine particles, degrades the soil strength and deformation moduli, and adversely impacts the cutoff walls of the dam foundation, as well as the
[...] Read more.
Suffusion erosion may occur in sandy gravel dam foundations that use suspended cutoff walls. This erosion causes a loss of fine particles, degrades the soil strength and deformation moduli, and adversely impacts the cutoff walls of the dam foundation, as well as the overlying dam body. A comprehensive evaluation of these effects requires models that quantitatively describe the effects of fine particle losses on the stress-strain relationships of sandy gravels. In this work, we propose an experimental scheme for studying these types of models, and then perform triaxial and confined compression tests to determine the effects of particle losses on the stress-strain relationships. Considering the Duncan-Chang E-B model, quantitative expressions describing the relationship between the parameters of the model and the particle losses were derived. The results show that particle losses did not alter the qualitative stress-strain characteristics of the soils; however, the soil strength and deformation moduli were degraded. By establishing the relationship between the parameters of the model and the losses, the same model can then be used to describe the relationship between sandy gravels and erosion levels that vary in both time and space. Full article
(This article belongs to the Section Porous Materials)
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Open AccessArticle Cl-Assisted Large Scale Synthesis of Cm-Scale Buckypapers of Fe3C-Filled Carbon Nanotubes with Pseudo-Capacitor Properties: The Key Role of SBA-16 Catalyst Support as Synthesis Promoter
Materials 2017, 10(10), 1216; https://doi.org/10.3390/ma10101216
Received: 24 July 2017 / Revised: 26 September 2017 / Accepted: 20 October 2017 / Published: 23 October 2017
PDF Full-text (4149 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We show a novel chemical vapour deposition (CVD) approach, in which the large-scale fabrication of ferromagnetically-filled cm-scale buckypapers is achieved through the deposition of a mesoporous supported catalyst (SBA-16) on a silicon substrate. We demonstrate that SBA-16 has the crucial role of promoting
[...] Read more.
We show a novel chemical vapour deposition (CVD) approach, in which the large-scale fabrication of ferromagnetically-filled cm-scale buckypapers is achieved through the deposition of a mesoporous supported catalyst (SBA-16) on a silicon substrate. We demonstrate that SBA-16 has the crucial role of promoting the growth of carbon nanotubes (CNTs) on a horizontal plane with random orientation rather than in a vertical direction, therefore allowing a facile fabrication of cm-scale CNTs buckypapers free from the onion-crust by-product observed on the buckypaper-surface in previous reports. The morphology and composition of the obtained CNTs-buckypapers are analyzed in detail by scanning electron microscopy (SEM), Energy Dispersive X-ray (EDX), transmission electron microscopy (TEM), high resolution TEM (HRTEM), and thermogravimetric analysis (TGA), while structural analysis is performed by Rietveld Refinement of XRD data. The room temperature magnetic properties of the produced buckypapers are also investigated and reveal the presence of a high coercivity of 650 Oe. Additionally, the electrochemical performances of these buckypapers are demonstrated and reveal a behavior that is compatible with that of a pseudo-capacitor (resistive-capacitor) with better performances than those presented in other previously studied layered-buckypapers of Fe-filled CNTs, obtained by pyrolysis of dichlorobenzene-ferrocene mixtures. These measurements indicate that these materials show promise for applications in energy storage systems as flexible electrodes. Full article
(This article belongs to the Section Porous Materials)
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Open AccessArticle Effect of Nano-CuO on Engineering and Microstructure Properties of Fibre-Reinforced Mortars Incorporating Metakaolin: Experimental and Numerical Studies
Materials 2017, 10(10), 1215; https://doi.org/10.3390/ma10101215
Received: 29 September 2017 / Revised: 18 October 2017 / Accepted: 19 October 2017 / Published: 23 October 2017
Cited by 4 | PDF Full-text (6087 KB) | HTML Full-text | XML Full-text
Abstract
In this study, the effects of nano-CuO (NC) on engineering properties of fibre-reinforced mortars incorporating metakaolin (MK) were investigated. The effects of polypropylene fibre (PP) were also examined. A total of twenty-six mixtures were prepared. The experimental results were compared with numerical results
[...] Read more.
In this study, the effects of nano-CuO (NC) on engineering properties of fibre-reinforced mortars incorporating metakaolin (MK) were investigated. The effects of polypropylene fibre (PP) were also examined. A total of twenty-six mixtures were prepared. The experimental results were compared with numerical results obtained by adaptive neuro-fuzzy inference system (ANFIS) and Primal Estimated sub-GrAdient Solver for SVM (Pegasos) algorithm. Scanning Electron Microscope (SEM) was also employed to investigate the microstructure of the cement matrix. The mechanical test results showed that both compressive and flexural strengths of cement mortars decreased with the increase of MK content, however the strength values increased significantly with increasing NC content in the mixture. The water absorption of samples decreased remarkably with increasing NC particles in the mixture. When PP fibres were added, the strengths of cement mortars were further enhanced accompanied with lower water absorption values. The addition of 2 wt % and 3 wt % nanoparticles in cement mortar led to a positive contribution to strength and resistance to water absorption. Mixture of PP-MK10NC3 indicated the best results for both compressive and flexural strengths at 28 and 90 days. SEM images illustrated that the morphology of cement matrix became more porous with increasing MK content, but the porosity reduced with the inclusion of NC. In addition, it is evident from the SEM images that more cement hydration products adhered onto the surface of fibres, which would improve the fibre–matrix interface. The numerical results obtained by ANFIS and Pegasos were close to the experimental results. The value of R2 obtained for each data set (validate, test and train) was higher than 0.90 and the values of mean absolute percentage error (MAPE) and the relative root mean squared error (PRMSE) were near zero. The ANFIS and Pegasos models can be used to predict the mechanical properties and water absorptions of fibre-reinforced mortars with MK and NC. Full article
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Open AccessReview Activation of Alkaline Irrigation Fluids in Endodontics
Materials 2017, 10(10), 1214; https://doi.org/10.3390/ma10101214
Received: 12 September 2017 / Revised: 4 October 2017 / Accepted: 20 October 2017 / Published: 23 October 2017
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Abstract
In conventional endodontic treatment, alkaline solutions of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are used in combination to disinfect the root canal system and to eliminate debris and smear layers. An important concept that has emerged over recent years is the use
[...] Read more.
In conventional endodontic treatment, alkaline solutions of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are used in combination to disinfect the root canal system and to eliminate debris and smear layers. An important concept that has emerged over recent years is the use of active physical methods for agitating these fluids to improve their penetration within areas that are not reached by endodontic instruments and to accelerate the chemical actions of these alkaline fluids against planktonic microorganisms, biofilms, soft tissue remnants and smear layers. Ultrasonic agitation and more recently pulsed lasers have emerged as two promising methods for activating endodontic irrigation fluids. Ultrasonic agitation with piezoelectric devices employs a moving tip, while laser agitation uses a stationary tip. Both methods cause cavitation, followed by implosions and shear forces which assist with debridement. Fluid streaming further enhances the activity of the fluids. While agitation enhances performance of irrigants, extrusion of fluids from the root canal during activation is a hazard that must be controlled. Full article
(This article belongs to the Special Issue Dental Biomaterials 2017)
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Open AccessCase Report Treatment of Severely Resorbed Maxilla Due to Peri-Implantitis by Guided Bone Regeneration Using a Customized Allogenic Bone Block: A Case Report
Materials 2017, 10(10), 1213; https://doi.org/10.3390/ma10101213
Received: 4 October 2017 / Revised: 18 October 2017 / Accepted: 19 October 2017 / Published: 21 October 2017
Cited by 3 | PDF Full-text (1276 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this case report is to introduce a customized CAD/CAM freeze-dried bone allograft (FDBA) block for its use in Guided Bone Regeneration (GBR) procedures for severely deficient maxillary bones. Additionally, a special newly developed remote incision technique is presented to avoid
[...] Read more.
The objective of this case report is to introduce a customized CAD/CAM freeze-dried bone allograft (FDBA) block for its use in Guided Bone Regeneration (GBR) procedures for severely deficient maxillary bones. Additionally, a special newly developed remote incision technique is presented to avoid wound dehiscence. The results show optimal integration behavior of the FDBA block after six months and the formation of new vital bone. Thus, the results of the present case report confirm the use of the customized CAD/CAM bone block for augmentation of complex defects in the maxillary aesthetic zone as a successful treatment concept. Full article
(This article belongs to the Special Issue Dental Biomaterials 2017)
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Open AccessArticle Assembly of 1D Granular Structures from Sulfonated Polystyrene Microparticles
Materials 2017, 10(10), 1212; https://doi.org/10.3390/ma10101212
Received: 9 October 2017 / Revised: 9 October 2017 / Accepted: 17 October 2017 / Published: 21 October 2017
PDF Full-text (2304 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Being able to systematically modify the electric properties of nano- and microparticles opens up new possibilities for the bottom-up fabrication of advanced materials such as the fabrication of one-dimensional (1D) colloidal and granular materials. Fabricating 1D structures from individual particles offers plenty of
[...] Read more.
Being able to systematically modify the electric properties of nano- and microparticles opens up new possibilities for the bottom-up fabrication of advanced materials such as the fabrication of one-dimensional (1D) colloidal and granular materials. Fabricating 1D structures from individual particles offers plenty of applications ranging from electronic sensors and photovoltaics to artificial flagella for hydrodynamic propulsion. In this work, we demonstrate the assembly of 1D structures composed of individual microparticles with modified electric properties, pulled out of a liquid environment into air. Polystyrene particles were modified by sulfonation for different reaction times and characterized by dielectric spectroscopy and dipolar force measurements. We found that by increasing the sulfonation time, the values of both electrical conductivity and dielectric constant of the particles increase, and that the relaxation frequency of particle electric polarization changes, causing the measured dielectric loss of the particles to shift towards higher frequencies. We attributed these results to water adsorbed at the surface of the particles. With sulfonated polystyrene particles exhibiting a range of electric properties, we showed how the electric properties of individual particles influence the formation of 1D structures. By tuning applied voltage and frequency, we were able to control the formation and dynamics of 1D structures, including chain bending and oscillation. Full article
(This article belongs to the Special Issue Designed Colloidal Self-Assembly)
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Open AccessArticle Time-Variant Reliability Analysis for Rubber O-Ring Seal Considering Both Material Degradation and Random Load
Materials 2017, 10(10), 1211; https://doi.org/10.3390/ma10101211
Received: 1 September 2017 / Revised: 16 October 2017 / Accepted: 17 October 2017 / Published: 20 October 2017
Cited by 3 | PDF Full-text (4840 KB) | HTML Full-text | XML Full-text
Abstract
Due to the increase in working hours, the reliability of rubber O-ring seals used in hydraulic systems of transfer machines will change. While traditional methods can only analyze one of the material properties or seal properties, the failure of the O-ring is caused
[...] Read more.
Due to the increase in working hours, the reliability of rubber O-ring seals used in hydraulic systems of transfer machines will change. While traditional methods can only analyze one of the material properties or seal properties, the failure of the O-ring is caused by these two factors together. In this paper, two factors are mainly analyzed: the degradation of material properties and load randomization by processing technology. Firstly, the two factors are defined in terms of material failure and seal failure, before the experimental methods of rubber materials are studied. Following this, the time-variant material properties through experiments and load distribution by monitoring the processing can be obtained. Thirdly, compressive stress and contact stress have been calculated, which was combined with the reliability model to acquire the time-variant reliability for the O-ring. Finally, the life prediction and effect of oil pressure were discussed, then compared with the actual situation. The results show a lifetime of 12 months for the O-ring calculated in this paper, and compared with the replacement records from the maintenance workshop, the result is credible. Full article
(This article belongs to the Special Issue Contact Mechanics and Elastomer Friction of Materials)
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Open AccessArticle Preparation and Characterization of Ternary Antimicrobial Films of β-Cyclodextrin/Allyl Isothiocyanate/Polylactic Acid for the Enhancement of Long-Term Controlled Release
Materials 2017, 10(10), 1210; https://doi.org/10.3390/ma10101210
Received: 19 September 2017 / Revised: 11 October 2017 / Accepted: 12 October 2017 / Published: 20 October 2017
Cited by 2 | PDF Full-text (2036 KB) | HTML Full-text | XML Full-text
Abstract
Allyl isothiocyanate (AITC) are natural essential oil components that have outstanding antimicrobial activities. However, low water solubility, high volatility, and easy degradation by heat, restricting their application in food packing industry. Development of the inclusion complex of β-cyclodextrin/AITC (β-CD/AITC) is a promising solution.
[...] Read more.
Allyl isothiocyanate (AITC) are natural essential oil components that have outstanding antimicrobial activities. However, low water solubility, high volatility, and easy degradation by heat, restricting their application in food packing industry. Development of the inclusion complex of β-cyclodextrin/AITC (β-CD/AITC) is a promising solution. Furthermore, the incorporation of β-CD/AITC complex into polylactic acid (PLA) films would be an attractive method to develop food antimicrobial materials. The aim of this study was to evaluate the enhancement in physicochemical properties, antimicrobial activities, and controlled release of β-CD/AITC from such films. The addition of β-CD/AITC significantly increased the flexibility and thermal stability of films. The Fourier transform infrared (FTIR) results revealed that the interactions between β-CD/AITC and PLA films occurred. The controlled release of AITC encapsulated in β-CD was significantly affected by relative humidity and temperature. The PLA films containing β-CD/AITC can be applied as an effective antimicrobial packing material for food and non-food applications. Full article
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Open AccessFeature PaperCommunication Magnetic Properties of Fibonacci-Modulated Fe-Au Multilayer Metamaterials
Materials 2017, 10(10), 1209; https://doi.org/10.3390/ma10101209
Received: 1 August 2017 / Revised: 12 October 2017 / Accepted: 17 October 2017 / Published: 20 October 2017
Cited by 1 | PDF Full-text (1176 KB) | HTML Full-text | XML Full-text
Abstract
Herein we experimentally study magnetic multilayer metamaterials with broken translational symmetry. Epitaxially-grown iron-gold (Fe-Au) multilayers modulated using Fibonacci sequence—referred to as magnetic inverse Fibonacci-modulated multilayers (IFMs)—are prepared using ultra-high-vacuum vapor deposition. Experimental results of in-situ reflection high-energy electron diffraction, magnetization curves, and ferromagnetic
[...] Read more.
Herein we experimentally study magnetic multilayer metamaterials with broken translational symmetry. Epitaxially-grown iron-gold (Fe-Au) multilayers modulated using Fibonacci sequence—referred to as magnetic inverse Fibonacci-modulated multilayers (IFMs)—are prepared using ultra-high-vacuum vapor deposition. Experimental results of in-situ reflection high-energy electron diffraction, magnetization curves, and ferromagnetic resonance demonstrate that the epitaxially-grown Fe-Au IFMs have quasi-isotropic magnetization, in contrast to the in-plane magnetization easy axis in the periodic multilayers. Full article
(This article belongs to the Special Issue Advance in Plasmonics and Metamaterials)
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Open AccessArticle Synthesis and Characterization of TiO2 Nanoparticles for the Reduction of Water Pollutants
Materials 2017, 10(10), 1208; https://doi.org/10.3390/ma10101208
Received: 30 August 2017 / Revised: 13 October 2017 / Accepted: 18 October 2017 / Published: 20 October 2017
Cited by 2 | PDF Full-text (1424 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The aim of this manuscript was the optimization of the synthesis of TiO2 nanoparticles (TiO2 NPs) with conditions that could be easily reproducible at the industrial level. Several procedures were tested and those with C12H28O4Ti
[...] Read more.
The aim of this manuscript was the optimization of the synthesis of TiO2 nanoparticles (TiO2 NPs) with conditions that could be easily reproducible at the industrial level. Several procedures were tested and those with C12H28O4Ti and CO(NH2)2 as precursors seemed the most promising and, consequently, were improved with different molar ratios, lower temperatures and the addition of NH4Cl as a secondary dopant of nitrogen. The obtained samples were studied with analytical techniques such as X-ray powder diffraction (XRPD) and field emission scanning electron microscopy (FESEM). To complete the study, dye degradation and bacteriological tests were also performed. The results indicate that it is possible to obtain TiO2 NPs at lower temperatures with respect to those used in the literature; the best candidate that could satisfy all the requirements was a sample with a molar ratio of C12H28O4Ti:CO(NH2)2 at 2:1 and obtained at 50 °C. Full article
(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)
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Open AccessArticle Modeling and Predicting the Stress Relaxation of Composites with Short and Randomly Oriented Fibers
Materials 2017, 10(10), 1207; https://doi.org/10.3390/ma10101207
Received: 12 September 2017 / Revised: 9 October 2017 / Accepted: 17 October 2017 / Published: 20 October 2017
PDF Full-text (1704 KB) | HTML Full-text | XML Full-text
Abstract
The addition of short fibers has been experimentally observed to slow the stress relaxation of viscoelastic polymers, producing a change in the relaxation time constant. Our recent study attributed this effect of fibers on stress relaxation behavior to the interfacial shear stress transfer
[...] Read more.
The addition of short fibers has been experimentally observed to slow the stress relaxation of viscoelastic polymers, producing a change in the relaxation time constant. Our recent study attributed this effect of fibers on stress relaxation behavior to the interfacial shear stress transfer at the fiber-matrix interface. This model explained the effect of fiber addition on stress relaxation without the need to postulate structural changes at the interface. In our previous study, we developed an analytical model for the effect of fully aligned short fibers, and the model predictions were successfully compared to finite element simulations. However, in most industrial applications of short-fiber composites, fibers are not aligned, and hence it is necessary to examine the time dependence of viscoelastic polymers containing randomly oriented short fibers. In this study, we propose an analytical model to predict the stress relaxation behavior of short-fiber composites where the fibers are randomly oriented. The model predictions were compared to results obtained from Monte Carlo finite element simulations, and good agreement between the two was observed. The analytical model provides an excellent tool to accurately predict the stress relaxation behavior of randomly oriented short-fiber composites. Full article
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Open AccessArticle L21 and XA Ordering Competition in Hafnium-Based Full-Heusler Alloys Hf2VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb)
Materials 2017, 10(10), 1200; https://doi.org/10.3390/ma10101200
Received: 16 September 2017 / Revised: 15 October 2017 / Accepted: 15 October 2017 / Published: 20 October 2017
Cited by 5 | PDF Full-text (9515 KB) | HTML Full-text | XML Full-text
Abstract
For theoretical designing of full-Heusler based spintroinc materials, people have long believed in the so-called Site Preference Rule (SPR). Very recently, according to the SPR, there are several studies on XA-type Hafnium-based Heusler alloys X2YZ, i.e., Hf2VAl, Hf2
[...] Read more.
For theoretical designing of full-Heusler based spintroinc materials, people have long believed in the so-called Site Preference Rule (SPR). Very recently, according to the SPR, there are several studies on XA-type Hafnium-based Heusler alloys X2YZ, i.e., Hf2VAl, Hf2CoZ (Z = Ga, In) and Hf2CrZ (Z = Al, Ga, In). In this work, a series of Hf2-based Heusler alloys, Hf2VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb), were selected as targets to study the site preferences of their atoms by first-principle calculations. It has been found that all of them are likely to exhibit the L21-type structure instead of the XA one. Furthermore, we reveal that the high values of spin-polarization of XA-type Hf2VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb) alloys have dropped dramatically when they form the L21-type structure. Also, we prove that the electronic, magnetic, and physics nature of these alloys are quite different, depending on the L21-type or XA-type structures. Full article
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Open AccessArticle Impacts of Modification of Alloying Method on Inclusion Evolution in RH Refining of Silicon Steel
Materials 2017, 10(10), 1206; https://doi.org/10.3390/ma10101206
Received: 28 September 2017 / Revised: 15 October 2017 / Accepted: 16 October 2017 / Published: 19 October 2017
Cited by 1 | PDF Full-text (4902 KB) | HTML Full-text | XML Full-text
Abstract
This study explores the effect of introducing additional alloy elements not only in a different order but also at different stages of the Ruhrstahl-Heraeus (RH) process of low-carbon silicon steel production. A more economical method, described as “pre-alloying”, has been introduced. The evolution
[...] Read more.
This study explores the effect of introducing additional alloy elements not only in a different order but also at different stages of the Ruhrstahl-Heraeus (RH) process of low-carbon silicon steel production. A more economical method, described as “pre-alloying”, has been introduced. The evolution of MnO-FeO inclusions produced by pre-alloying was investigated. Results show that spherical 3FeO·MnO inclusions form first, then shelled FeO·zMnO (z = 0.7–4) inclusions nucleate on the surface of pre-existing 3FeO·MnO. Spherical FeO·zMnO (z = 3–5) is further evolved from shelled 3FeO·MnO by diffusion. Because these MnO-FeO inclusions float up into the slag before degassing, the pre-alloying process does not affect the quality of the melt in the end. Both carbon content and inclusion size conform to industry standards. Full article
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Open AccessArticle Nucleation/Growth Mechanisms and Morphological Evolution of Porous MnO2 Coating Deposited on Graphite for Supercapacitor
Materials 2017, 10(10), 1205; https://doi.org/10.3390/ma10101205
Received: 6 September 2017 / Revised: 9 October 2017 / Accepted: 16 October 2017 / Published: 19 October 2017
Cited by 2 | PDF Full-text (11275 KB) | HTML Full-text | XML Full-text
Abstract
The nucleation and growth mechanisms of porous MnO2 coating deposited on graphite in MnSO4 solution were investigated in detail by cyclic voltammetry, chronoamperometry and scanning electron microscopy. The electrochemical properties of honeycomb-like MnO2 were evaluated by cycle voltammetry and galvanostatic
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The nucleation and growth mechanisms of porous MnO2 coating deposited on graphite in MnSO4 solution were investigated in detail by cyclic voltammetry, chronoamperometry and scanning electron microscopy. The electrochemical properties of honeycomb-like MnO2 were evaluated by cycle voltammetry and galvanostatic charge-discharge. Results indicated that MnO2 was synthesized by the following steps: Mn2+ Mn3++ e-, Mn3++2H2O → MnOOH + 3H+, and MnOOHMnO2 + H++ e-. The deposition of MnO2 was divided into four stages. A short incubation period (approximately 1.5 s) was observed, prior to nucleation. The decreasing trend of the current slowed as time increased due to nucleation and MnO2 growth in the second stage. A huge number of nuclei were formed by instantaneous nucleation, and these nuclei grew and connected with one another at an exceedingly short time (0.5 s). In the third stage, the gaps in-between initial graphite flakes were filled with MnO2 until the morphology of the flakes gradually became similar to that of the MnO2-deposited layer. In the fourth stage, the graphite electrode was covered completely with a thick and dense layer of MnO2 deposits. All MnO2 electrodes at different deposition times obtained nearly the same specific capacitance of approximately 186 F/g, thus indicating that the specific capacitance of the electrodes is not related with deposition time. Full article
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Open AccessFeature PaperArticle Graded Microstructure and Mechanical Performance of Ti/N-Implanted M50 Steel with Polyenergy
Materials 2017, 10(10), 1204; https://doi.org/10.3390/ma10101204
Received: 27 August 2017 / Revised: 11 October 2017 / Accepted: 12 October 2017 / Published: 19 October 2017
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Abstract
M50 bearing steels were alternately implanted with Ti+ and N+ ions using solid and gas ion sources of implantation system, respectively. N-implantation was carried out at an energy of about 80 keV and a fluence of 2 × 1017 ions/cm
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M50 bearing steels were alternately implanted with Ti+ and N+ ions using solid and gas ion sources of implantation system, respectively. N-implantation was carried out at an energy of about 80 keV and a fluence of 2 × 1017 ions/cm2, and Ti-implantation at an energy of about 40–90 keV and a fluence of 2 × 1017 ions/cm2. The microstructures of modification layers were analyzed by grazing-incidence X-ray diffraction, auger electron spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results showed that the gradient structure was formed under the M50 bearing steel subsurface, along the ion implantation influence zone composed of amorphous, nanocrystalline, and gradient-refinement phases. A layer of precipitation compounds like TiN is formed. In addition, nano-indentation hardness and tribological properties of the gradient structure subsurface were examined using a nano-indenter and a friction and wear tester. The nano-indentation hardness of N + Ti-co-implanted sample is above 12 GPa, ~1.3 times than that of pristine samples. The friction coefficient is smaller than 0.2, which is 22.2% of that of pristine samples. The synergism between precipitation-phase strengthening and gradient microstructure is the main mechanism for improving the mechanical properties of M50 materials. Full article
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Open AccessArticle Influence of Ultrasonic Surface Rolling on Microstructure and Wear Behavior of Selective Laser Melted Ti-6Al-4V Alloy
Materials 2017, 10(10), 1203; https://doi.org/10.3390/ma10101203
Received: 14 September 2017 / Revised: 8 October 2017 / Accepted: 17 October 2017 / Published: 19 October 2017
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Abstract
The present article studied the effect of ultrasonic surface rolling process (USRP) on the microstructure and wear behavior of a selective laser melted Ti-6Al-4V alloy. Surface characteristics were investigated using optical microscope, nano-indentation, scanning electron microscope, transmission electron microscope and laser scanning confocal
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The present article studied the effect of ultrasonic surface rolling process (USRP) on the microstructure and wear behavior of a selective laser melted Ti-6Al-4V alloy. Surface characteristics were investigated using optical microscope, nano-indentation, scanning electron microscope, transmission electron microscope and laser scanning confocal microscope. Results indicated that the thickness of pore-free surfaces increased to 100~200 μm with the increasing ultrasonic surface rolling numbers. Severe work hardening occurred in the densified layer, resulting in the formation of refined grains, dislocation walls and deformation twins. After 1000 N 6 passes, about 15.5% and 14.1% increment in surficial Nano-hardness and Vickers-hardness was obtained, respectively. The hardness decreased gradually from the top surface to the substrate. Wear tests revealed that the friction coefficient declined from 0.74 (polished surface) to 0.64 (USRP treated surface) and the wear volume reduced from 0.205 mm−3 to 0.195 mm−3. The difference in wear volume between USRP treated and polished samples increased with sliding time. The enhanced wear resistance was concluded to be associated with the improvement of hardness and shear resistance and also the inhibition of delamination initiation. Full article
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Open AccessFeature PaperArticle A Practical Example of GaN-LED Failure Cause Analysis by Application of Combined Electron Microscopy Techniques
Materials 2017, 10(10), 1202; https://doi.org/10.3390/ma10101202
Received: 25 July 2017 / Revised: 8 October 2017 / Accepted: 17 October 2017 / Published: 19 October 2017
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Abstract
In this paper, we report a failure case of blue LEDs returned from a field application, and propose a practical way to identify the physical and structural reasons for the observed malfunction by a combination of different electron microscope techniques. Cathodoluminescence imaging and
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In this paper, we report a failure case of blue LEDs returned from a field application, and propose a practical way to identify the physical and structural reasons for the observed malfunction by a combination of different electron microscope techniques. Cathodoluminescence imaging and electron beam induced current (EBIC) imaging are employed in order to visualize conductive paths through the device in conjunction with subsequent energy dispersive x-ray analysis (EDS), revealing a metal deposition along cracks in the semiconductor layer which short-circuit the device. We demonstrate that the electron beam induced current imaging, in conjunction with other microscopic and analytical techniques at µm scale, is a powerful combination for clearly resolving and visualizing the cause of failure in the GaN LED chip. However, this represents a case study of a real application, which may not have been generally observed in laboratory testing environment. Full article
(This article belongs to the Special Issue Light Emitting Diodes and Laser Diodes: Materials and Devices)
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Open AccessArticle Finite Element Modeling of Tensile Deformation Behaviors of Iron Syntactic Foam with Hollow Glass Microspheres
Materials 2017, 10(10), 1201; https://doi.org/10.3390/ma10101201
Received: 18 August 2017 / Revised: 12 October 2017 / Accepted: 17 October 2017 / Published: 19 October 2017
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Abstract
The elastoplastic deformation behaviors of hollow glass microspheres/iron syntactic foam under tension were modeled using a representative volume element (RVE) approach. The three-dimensional microstructures of the iron syntactic foam with 5 wt % glass microspheres were reconstructed using the random sequential adsorption algorithm.
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The elastoplastic deformation behaviors of hollow glass microspheres/iron syntactic foam under tension were modeled using a representative volume element (RVE) approach. The three-dimensional microstructures of the iron syntactic foam with 5 wt % glass microspheres were reconstructed using the random sequential adsorption algorithm. The constitutive behavior of the elastoplasticity in the iron matrix and the elastic-brittle failure for the glass microsphere were simulated in the models. An appropriate RVE size was statistically determined by evaluating elastic modulus, Poisson’s ratio, and yield strength in terms of model sizes and boundary conditions. The model was validated by the agreement with experimental findings. The tensile deformation mechanism of the syntactic foam considering the fracture of the microspheres was then investigated. In addition, the feasibility of introducing the interfacial deboning behavior to the proposed model was briefly investigated to improve the accuracy in depicting fracture behaviors of the syntactic foam. It is thought that the modeling techniques and the model itself have major potential for applications not only in the study of hollow glass microspheres/iron syntactic foams, but also for the design of composites with a high modulus matrix and high strength reinforcement. Full article
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Open AccessArticle Three-Dimensional (3D) Printing of Polymer-Metal Hybrid Materials by Fused Deposition Modeling
Materials 2017, 10(10), 1199; https://doi.org/10.3390/ma10101199
Received: 31 August 2017 / Revised: 15 October 2017 / Accepted: 16 October 2017 / Published: 19 October 2017
Cited by 9 | PDF Full-text (11815 KB) | HTML Full-text | XML Full-text
Abstract
Fused deposition modeling (FDM) is a three-dimensional (3D) printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with
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Fused deposition modeling (FDM) is a three-dimensional (3D) printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with functional materials are also commercially available. Especially combinations of polymers with metal particles result in printed objects with interesting optical and mechanical properties. The mechanical properties of objects printed with two of these metal-polymer blends were compared to common poly (lactide acid) (PLA) printed objects. Tensile tests and bending tests show that hybrid materials mostly containing bronze have significantly reduced mechanical properties. Tensile strengths of the 3D-printed objects were unexpectedly nearly identical with those of the original filaments, indicating sufficient quality of the printing process. Our investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength. Full article
(This article belongs to the Special Issue Perspectives on Additively Manufactured Metallic Materials)
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Open AccessArticle Predictive Parameters of Oral Health Quality of Life in Complete Mandibular Denture Wearers Stabilized by Mini-Implants: A Two-Year Follow-Up Study
Materials 2017, 10(10), 1197; https://doi.org/10.3390/ma10101197
Received: 28 August 2017 / Revised: 3 October 2017 / Accepted: 10 October 2017 / Published: 19 October 2017
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Abstract
The frequent instability of mandibular removable complete dentures affects patient Oral Health Related Quality of Life (OHRQoL). An innovative therapeutic strategy used to improve stability involves placing four symphyseal mini-implants. This study was aimed at assessing OHRQoL over time in subjects in which
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The frequent instability of mandibular removable complete dentures affects patient Oral Health Related Quality of Life (OHRQoL). An innovative therapeutic strategy used to improve stability involves placing four symphyseal mini-implants. This study was aimed at assessing OHRQoL over time in subjects in which mini-implants were placed and exploring if certain parameters could predict the evolution of their OHRQoL. The OHRQoL of subjects with dentures was assessed using the Geriatric Oral Health Assessment Index (GOHAI) before (T0), 2–6 months (T1), twelve months (T2) and twenty-four or more months (T3) after mini-implant setting. Age, gender and chewing ability were tested as explanatory variables for the change in OHRQoL with time. Thirteen women and six men were included (mean age: 69 ± 10 years). After treatment, mean GOHAI scores at T1, T2 and T3 increased significantly (p < 0.001). The GOHAI-Add mean score was not affected by age or gender. Baseline chewing ability impacted the “functional” and “pain and discomfort” fields of the mean GOHAI scores (p < 0.05). The OHRQoL quickly improved after mini-implant placement in complete denture wearers and then stabilized over time. Baseline chewing ability can be used as a predictive parameter of OHRQoL. Full article
(This article belongs to the Special Issue Dental Implant Materials)
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Open AccessArticle Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers
Materials 2017, 10(10), 1179; https://doi.org/10.3390/ma10101179
Received: 31 August 2017 / Revised: 29 September 2017 / Accepted: 12 October 2017 / Published: 19 October 2017
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Abstract
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, G
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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 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs) and boron nitride nanotubes (BNNTs) were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly. Full article
(This article belongs to the Special Issue Improving Performance of Nanocomposite Materials)
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Open AccessArticle Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ Phosphors
Materials 2017, 10(10), 1198; https://doi.org/10.3390/ma10101198
Received: 15 September 2017 / Revised: 11 October 2017 / Accepted: 16 October 2017 / Published: 18 October 2017
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Abstract
(Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al2
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(Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al2O4:Eu2+,Dy3+ phosphors, the different phase formation from monoclinic SrAl2O4 phase to hexagonal SrAl2O4 phase to monoclinic CaAl2O4 phase was observed when the Ca content increased. The emission color of SrAl2O4:Eu2+, Dy3+ phosphors varied from green to blue. For the (Sr, Ba)Al2O4:Eu2+, Dy3+ phosphors, different phase formation from the monoclinic SrAl2O4 phase to the hexagonal BaAl2O4 phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl2O4:Eu2+, Dy3+changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr2+ with Ba2+ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips. Full article
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Open AccessArticle Magnetron Sputtering as a Fabrication Method for a Biodegradable Fe32Mn Alloy
Materials 2017, 10(10), 1196; https://doi.org/10.3390/ma10101196
Received: 25 August 2017 / Revised: 22 September 2017 / Accepted: 11 October 2017 / Published: 18 October 2017
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Abstract
Biodegradable metals are a topic of great interest and Fe-based materials are prominent examples. The research task is to find a suitable compromise between mechanical, corrosion, and magnetic properties. For this purpose, investigations regarding alternative fabrication processes are important. In the present study,
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Biodegradable metals are a topic of great interest and Fe-based materials are prominent examples. The research task is to find a suitable compromise between mechanical, corrosion, and magnetic properties. For this purpose, investigations regarding alternative fabrication processes are important. In the present study, magnetron sputtering technology in combination with UV-lithography was used in order to fabricate freestanding, microstructured Fe32Mn films. To adjust the microstructure and crystalline phase composition with respect to the requirements, the foils were post-deposition annealed under a reducing atmosphere. The microstructure and crystalline phase composition were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Furthermore, for mechanical characterization, uniaxial tensile tests were performed. The in vitro corrosion rates were determined by electrochemical polarization measurements in pseudo-physiological solution. Additionally, the magnetic properties were measured via vibrating sample magnetometry. The foils showed a fine-grained structure and a tensile strength of 712 MPa, which is approximately a factor of two higher compared to the sputtered pure Fe reference material. The yield strength was observed to be even higher than values reported in literature for alloys with similar composition. Against expectations, the corrosion rates were found to be lower in comparison to pure Fe. Since the annealed foils exist in the austenitic, and antiferromagnetic γ-phase, an additional advantage of the FeMn foils is the low magnetic saturation polarization of 0.003 T, compared to Fe with 1.978 T. This value is even lower compared to the SS 316L steel acting as a gold standard for implants, and thus enhances the MRI compatibility of the material. The study demonstrates that magnetron sputtering in combination with UV-lithography is a new concept for the fabrication of already in situ geometrically structured FeMn-based foils with promising mechanical and magnetic properties. Full article
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Open AccessArticle A New Cluster Analysis-Marker-Controlled Watershed Method for Separating Particles of Granular Soils
Materials 2017, 10(10), 1195; https://doi.org/10.3390/ma10101195
Received: 15 September 2017 / Revised: 11 October 2017 / Accepted: 15 October 2017 / Published: 18 October 2017
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Abstract
An accurate determination of particle-level fabric of granular soils from tomography data requires a maximum correct separation of particles. The popular marker-controlled watershed separation method is widely used to separate particles. However, the watershed method alone is not capable of producing the maximum
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An accurate determination of particle-level fabric of granular soils from tomography data requires a maximum correct separation of particles. The popular marker-controlled watershed separation method is widely used to separate particles. However, the watershed method alone is not capable of producing the maximum separation of particles when subjected to boundary stresses leading to crushing of particles. In this paper, a new separation method, named as Monash Particle Separation Method (MPSM), has been introduced. The new method automatically determines the optimal contrast coefficient based on cluster evaluation framework to produce the maximum accurate separation outcomes. Finally, the particles which could not be separated by the optimal contrast coefficient were separated by integrating cuboid markers generated from the clustering by Gaussian mixture models into the routine watershed method. The MPSM was validated on a uniformly graded sand volume subjected to one-dimensional compression loading up to 32 MPa. It was demonstrated that the MPSM is capable of producing the best possible separation of particles required for the fabric analysis. Full article
(This article belongs to the Section Structure Analysis and Characterization)
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Open AccessFeature PaperArticle The Dynamic Response and Vibration of Functionally Graded Carbon Nanotube-Reinforced Composite (FG-CNTRC) Truncated Conical Shells Resting on Elastic Foundations
Materials 2017, 10(10), 1194; https://doi.org/10.3390/ma10101194
Received: 30 August 2017 / Revised: 10 October 2017 / Accepted: 11 October 2017 / Published: 18 October 2017
Cited by 5 | PDF Full-text (2790 KB) | HTML Full-text | XML Full-text
Abstract
Based on the classical shell theory, the linear dynamic response of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) truncated conical shells resting on elastic foundations subjected to dynamic loads is presented. The truncated conical shells are reinforced by single-walled carbon nanotubes (SWCNTs) that vary
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Based on the classical shell theory, the linear dynamic response of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) truncated conical shells resting on elastic foundations subjected to dynamic loads is presented. The truncated conical shells are reinforced by single-walled carbon nanotubes (SWCNTs) that vary according to the linear functions of the shell thickness. The motion equations are solved by the Galerkin method and the fourth-order Runge–Kutta method. In numerical results, the influences of geometrical parameters, elastic foundations, natural frequency parameters, and nanotube volume fraction of FG-CNTRC truncated conical shells are investigated. The proposed results are validated by comparing them with those of other authors. Full article
(This article belongs to the Special Issue Improving Performance of Nanocomposite Materials)
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