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Materials, Volume 8, Issue 6 (June 2015), Pages 2849-3792

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Open AccessCorrection Correction: Long-Term Soft Denture Lining Materials. Materials 2014, 7(8), 5816-5842
Materials 2015, 8(6), 3791-3792; https://doi.org/10.3390/ma8063791
Received: 17 June 2015 / Accepted: 17 June 2015 / Published: 23 June 2015
Cited by 1 | PDF Full-text (283 KB) | HTML Full-text | XML Full-text
Abstract
In the published manuscript “Long-Term Soft Denture Lining Materials. Materials 2014, 7(8), 5816-5842” [1] we detected that in three places reference numbers were inserted incorrectly due to an error in the editing. [...] Full article
(This article belongs to the Section Biomaterials)
Open AccessArticle Microstructural Study on Molten Marks of Fire-Causing Copper Wires
Materials 2015, 8(6), 3776-3790; https://doi.org/10.3390/ma8063776
Received: 12 January 2015 / Revised: 1 June 2015 / Accepted: 15 June 2015 / Published: 22 June 2015
Cited by 1 | PDF Full-text (929 KB) | HTML Full-text | XML Full-text
Abstract
Although electrical fires constitute the greatest percentage of the main causes of building fires, the critical evidence used by fire investigators to identify electrical fires is not always convincing to the general public. In this study, we scrutinized the microstructures of fire-causing copper
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Although electrical fires constitute the greatest percentage of the main causes of building fires, the critical evidence used by fire investigators to identify electrical fires is not always convincing to the general public. In this study, we scrutinized the microstructures of fire-causing copper wires and simulated the external environmental conditions required for the formation of fire-causing arc beads. Our metallographic investigation revealed that the primary thermal dendrites of copper at the fire-causing arc bead grew parallel to one another, but in the opposite direction to the heat flow. We determined the relationships of the undercooling (∆T0), the growth velocity (ν), and the primary spacing (λ) of the dendrites with respect to the electrical wire’s diameter. Accordingly, fire investigators can now identify fire-causing arc beads in terms of these metallographic characteristics, thereby providing clear scientific evidence for litigant judgments of electrical fires. Full article
(This article belongs to the Section Structure Analysis and Characterization)
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Open AccessArticle Liquid- and Gas-Phase Diffusion of Ferrocene in Thin Films of Metal-Organic Frameworks
Materials 2015, 8(6), 3767-3775; https://doi.org/10.3390/ma8063767
Received: 5 May 2015 / Revised: 2 June 2015 / Accepted: 9 June 2015 / Published: 19 June 2015
Cited by 18 | PDF Full-text (832 KB) | HTML Full-text | XML Full-text
Abstract
The mass transfer of the guest molecules in nanoporous host materials, in particular in metal-organic frameworks (MOFs), is among the crucial features of their applications. By using thin surface-mounted MOF films in combination with a quartz crystal microbalance (QCM), the diffusion of ferrocene
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The mass transfer of the guest molecules in nanoporous host materials, in particular in metal-organic frameworks (MOFs), is among the crucial features of their applications. By using thin surface-mounted MOF films in combination with a quartz crystal microbalance (QCM), the diffusion of ferrocene vapor and of ethanolic and hexanic ferrocene solution in HKUST-1 was investigated. For the first time, liquid- and gas-phase diffusion in MOFs was compared directly in the identical sample. The diffusion coefficients are in the same order of magnitude (~10−16 m2·s−1), whereas the diffusion coefficient of ferrocene in the empty framework is roughly 3-times smaller than in the MOF which is filled with ethanol or n-hexane. Full article
(This article belongs to the Special Issue Diffusion under Confinement in Nanopores)
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Open AccessArticle Revealing New Structural Insights from Surfactant Micelles through DLS, Microrheology and Raman Spectroscopy
Materials 2015, 8(6), 3754-3766; https://doi.org/10.3390/ma8063754
Received: 12 May 2015 / Revised: 3 June 2015 / Accepted: 15 June 2015 / Published: 19 June 2015
Cited by 5 | PDF Full-text (1193 KB) | HTML Full-text | XML Full-text
Abstract
The correlation between molecular changes and microstructural evolution of rheological properties has been demonstrated for the first time in a mixed anionic/zwitterionic surfactant-based wormlike micellar system. Utilizing a novel combination of DLS-microrheology and Raman Spectroscopy, the effect of electrostatic screening on these properties
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The correlation between molecular changes and microstructural evolution of rheological properties has been demonstrated for the first time in a mixed anionic/zwitterionic surfactant-based wormlike micellar system. Utilizing a novel combination of DLS-microrheology and Raman Spectroscopy, the effect of electrostatic screening on these properties of anionic (SLES) and zwitterionic (CapB) surfactant mixtures was studied by modulating the NaCl concentration. As Raman Spectroscopy delivers information about the molecular structure and DLS-microrheology characterizes viscoelastic properties, the combination of data delivered allows for a deeper understanding of the molecular changes underlying the viscoelastic ones. The high frequency viscoelastic response obtained through DLS-microrheology has shown the persistence of the Maxwell fluid response for low viscosity solutions at high NaCl concentrations. The intensity of the Raman band at 170 cm1 exhibits very strong correlation with the viscosity variation. As this Raman band is assigned to hydrogen bonding, its variation with NaCl concentration additionally indicates differences in water structuring due to potential microstructural differences at low and high NaCl concentrations. The microstructural differences at low and high NaCl concentrations are further corroborated by persistence of a slow mode at the higher NaCl concentrations as seen through DLS measurements. The study illustrates the utility of the combined DLS, DLS-optical microrheology and Raman Spectroscopy in providing new molecular structural insights into the self-assembly process in complex fluids. Full article
(This article belongs to the Section Structure Analysis and Characterization)
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Open AccessArticle Seismic Experimental Study on New-Type Composite Exterior Wallboard with Integrated Structural Function and Insulation
Materials 2015, 8(6), 3732-3753; https://doi.org/10.3390/ma8063732
Received: 9 May 2015 / Revised: 5 June 2015 / Accepted: 15 June 2015 / Published: 19 June 2015
Cited by 4 | PDF Full-text (1962 KB) | HTML Full-text | XML Full-text
Abstract
In order to evaluate the seismic performance of new-type composite exterior wallboard, a total of six exterior and interior wallboards were incorporated in the experiment of seismic performance. Seismic performance such as the stress process, damage mode, hysteresis and skeleton curve, load-carrying and
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In order to evaluate the seismic performance of new-type composite exterior wallboard, a total of six exterior and interior wallboards were incorporated in the experiment of seismic performance. Seismic performance such as the stress process, damage mode, hysteresis and skeleton curve, load-carrying and ductility coefficient, damping and energy dissipation, stiffness degradation as well as material strain of the exterior wallboards were analyzed with emphasis and compared with interior wallboards. Results of the experiment and analysis showed that both interior and exterior wallboards exhibited outstanding seismic performance. Due to the existence of insulation layer and externally bonded single gypsum board, the capacity of elastoplastic deformation and seismic energy dissipation of the exterior wallboards was improved and each seismic performance indicator of the exterior wallboards outperformed the interior wallboards. Full article
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Open AccessArticle Properties of Cement Mortar by Use of Hot-Melt Polyamides as Substitute for Fine Aggregate
Materials 2015, 8(6), 3714-3731; https://doi.org/10.3390/ma8063714
Received: 10 April 2015 / Revised: 9 June 2015 / Accepted: 10 June 2015 / Published: 19 June 2015
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Abstract
This paper presents an experimental study on use of hot-melt polyamide (HMP) to prepare mortar specimens with improved crack healing and engineering properties. The role of HMP in the crack repairing of cement mortar subjected to several rounds of heat treatment was investigated.
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This paper presents an experimental study on use of hot-melt polyamide (HMP) to prepare mortar specimens with improved crack healing and engineering properties. The role of HMP in the crack repairing of cement mortar subjected to several rounds of heat treatment was investigated. Compatibility between HMP and hydraulic cement was investigated through X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR) technology. Mortar specimens were prepared using standard cement mortar mixes with HMP at 1%, 3% and 5% (by volume) for fine aggregate substitute. After curing for 28 days, HMP specimens were subjected to heating at temperature of 160 °C for one, two, and three days and then natural cooling down to ambient temperature. Mechanical and durability properties of the heated HMP mortars were evaluated and compared with those of the corresponding mortars without heating. The microscopic observation of the interfacial transition zone (ITZ) of HMP mortar was conducted through environmental scanning electron microscopy (ESEM). Results reveal that incorporation of HMP improves the workability of the HMP/cement binder while leading to decrease in compressive strength and durability. The heated HMP mortars after exposure to heating for one, two, and three days exhibit no obvious change in compressive strength while presenting notable increase in flexural strength and durability compared with the corresponding mortars without heating. The XRD, FTIR and ESEM analyses indicate that no obvious chemical reaction occurs between HMP and hydraulic cement, and thus the self-repairing for interfacial micro-crack in HMP/cement composite system is ascribed to the physical adhesion of HMP to cement matrix rather than the chemical bonding between them. Full article
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Open AccessArticle Mechanism of Filling and Feeding of Thin-Walled Structures during Gravity Casting
Materials 2015, 8(6), 3701-3713; https://doi.org/10.3390/ma8063701
Received: 19 May 2015 / Revised: 4 June 2015 / Accepted: 16 June 2015 / Published: 19 June 2015
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Abstract
The filling and feeding of thin-walled structures in metal castings pose significant difficulties in manufacturing aerospace structural materials. Samples containing 2 mm and 5 mm thin-walled structures were designed to study the kinetics of filling. The microstructural evolution of the solidification of thin-walled
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The filling and feeding of thin-walled structures in metal castings pose significant difficulties in manufacturing aerospace structural materials. Samples containing 2 mm and 5 mm thin-walled structures were designed to study the kinetics of filling. The microstructural evolution of the solidification of thin-walled structures was studied with synchrotron X-radiation imaging. The formation of dendritic networks and the isotherm profiles of samples of different thickness were examined. The experimental results showed solidification microstructures of 2 mm and 5 mm thin-walled parts containing elongated equiaxed grains and normal equiaxed grains, respectively. The filling and feeding abilities of thin-walled parts were found to depend more on the wall thickness than on the pouring temperature. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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Open AccessArticle 3D Printable Biophotopolymers for in Vivo Bone Regeneration
Materials 2015, 8(6), 3685-3700; https://doi.org/10.3390/ma8063685
Received: 5 May 2015 / Accepted: 9 June 2015 / Published: 19 June 2015
Cited by 6 | PDF Full-text (952 KB) | HTML Full-text | XML Full-text
Abstract
The present study investigated two novel biophotopolymer classes that are chemically based on non-toxic poly (vinyl alcohol). These vinylesters and vinylcarbonates were compared to standard acrylates in vitro on MC3T3-E1 cells and in vivo in a small animal model. In vitro, both
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The present study investigated two novel biophotopolymer classes that are chemically based on non-toxic poly (vinyl alcohol). These vinylesters and vinylcarbonates were compared to standard acrylates in vitro on MC3T3-E1 cells and in vivo in a small animal model. In vitro, both vinylester and vinylcarbonate monomers showed about tenfold less cytotoxicity when compared to acrylates (IC50: 2.922 mM and 2.392 mM vs. 0.201 mM) and at least threefold higher alkaline phosphatase activity (17.038 and 18.836 vs. 5.795, measured at [10 mM]). In vivo, polymerized 3D cellular structures were implanted into the distal femoral condyle of 16 New Zealand White Rabbits and were observed for periods from 4 to 12 weeks. New bone formation and bone to implant contact was evaluated by histomorphometry at end of observation. Vinylesters showed similar rates of new bone formation but significantly less (p = 0.002) bone to implant contact, when compared to acrylates. In contrast, the implantation of vinylcarbonate based biophotopolymers led to significantly higher rates of newly formed bone (p < 0.001) and bone to implant contact (p < 0.001). Additionally, distinct signs of polymer degradation could be observed in vinylesters and vinylcarbonates by histology. We conclude, that vinylesters and vinylcarbonates are promising new biophotopolymers, that outmatch available poly(lactic acid) and (meth)acrylate based materials. Full article
(This article belongs to the Special Issue Novel Bone Substitute Materials)
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Open AccessArticle The Modification of a Tetrafunctional Epoxy and Its Curing Reaction
Materials 2015, 8(6), 3671-3684; https://doi.org/10.3390/ma8063671
Received: 25 January 2015 / Revised: 8 June 2015 / Accepted: 8 June 2015 / Published: 18 June 2015
Cited by 2 | PDF Full-text (1584 KB) | HTML Full-text | XML Full-text
Abstract
Recent experimental results showed that the Tg of cured resin scarcely decreased and the impact strength of resins increased by over 50% when a tetrafunctional epoxy named N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether (TGDDE) was introduced to an appropriate
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Recent experimental results showed that the Tg of cured resin scarcely decreased and the impact strength of resins increased by over 50% when a tetrafunctional epoxy named N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether (TGDDE) was introduced to an appropriate flexible chain from a dimer fatty acid (DFA). In order to understand the reason for this phenomenon, the modification and the chemical structure of the prepolymer together with the curing reaction and the viscoelasticity of the cured resins were studied in detail in the present work. The results indicated that the modification would help the prepolymer improve its molecular mobility. As a result, the resins could be further cured, resulting in the cross-linking density increasing. This is because the curing efficiency was increased, but the tetrafunctional epoxy was not cured completely due to its large steric hindrance. Moreover, the flexibility of some parts of the networks was improved, which was beneficial for the toughness of the cured resins. Therefore, the toughness of the tetrafunctional resin was improved with little influence on the thermal properties when the epoxies were modified with an appropriate content of DFA. Full article
(This article belongs to the Special Issue Selected Papers from ICETI2014)
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Open AccessArticle Plasmonic Light Trapping in Thin-Film Solar Cells: Impact of Modeling on Performance Prediction
Materials 2015, 8(6), 3648-3670; https://doi.org/10.3390/ma8063648
Received: 27 May 2015 / Revised: 8 June 2015 / Accepted: 10 June 2015 / Published: 18 June 2015
Cited by 2 | PDF Full-text (6621 KB) | HTML Full-text | XML Full-text
Abstract
We present a comparative study on numerical models used to predict the absorption enhancement in thin-film solar cells due to the presence of structured back-reflectors exciting, at specific wavelengths, hybrid plasmonic-photonic resonances. To evaluate the effectiveness of the analyzed models, they have been
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We present a comparative study on numerical models used to predict the absorption enhancement in thin-film solar cells due to the presence of structured back-reflectors exciting, at specific wavelengths, hybrid plasmonic-photonic resonances. To evaluate the effectiveness of the analyzed models, they have been applied in a case study: starting from a U-shaped textured glass thin-film, µc-Si:H solar cells have been successfully fabricated. The fabricated cells, with different intrinsic layer thicknesses, have been morphologically, optically and electrically characterized. The experimental results have been successively compared with the numerical predictions. We have found that, in contrast to basic models based on the underlying schematics of the cell, numerical models taking into account the real morphology of the fabricated device, are able to effectively predict the cells performances in terms of both optical absorption and short-circuit current values. Full article
(This article belongs to the Special Issue Plasmonic Materials)
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Open AccessArticle Photocatalytic Membrane Reactor for the Removal of C.I. Disperse Red 73
Materials 2015, 8(6), 3633-3647; https://doi.org/10.3390/ma8063633
Received: 7 April 2015 / Revised: 15 May 2015 / Accepted: 11 June 2015 / Published: 18 June 2015
Cited by 6 | PDF Full-text (813 KB) | HTML Full-text | XML Full-text
Abstract
After the dyeing process, part of the dyes used to color textile materials are not fixed into the substrate and are discharged into wastewater as residual dyes. In this study, a heterogeneous photocatalytic process combined with microfiltration has been investigated for the removal
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After the dyeing process, part of the dyes used to color textile materials are not fixed into the substrate and are discharged into wastewater as residual dyes. In this study, a heterogeneous photocatalytic process combined with microfiltration has been investigated for the removal of C.I. Disperse Red 73 from synthetic textile effluents. The titanium dioxide (TiO2) Aeroxide P25 was selected as photocatalyst. The photocatalytic treatment achieved between 60% and 90% of dye degradation and up to 98% chemical oxygen demand (COD) removal. The influence of different parameters on photocatalytic degradation was studied: pH, initial photocatalyst loading, and dye concentration. The best conditions for dye degradation were pH 4, an initial dye concentration of 50 mg·L−1, and a TiO2 loading of 2 g·L1. The photocatalytic membrane treatment provided a high quality permeate, which can be reused. Full article
(This article belongs to the Special Issue Developments in Organic Dyes and Pigments)
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Open AccessArticle Adsorption, Thermodynamic and Quantum Chemical Studies of 1-hexyl-3-methylimidazolium Based Ionic Liquids as Corrosion Inhibitors for Mild Steel in HCl
Materials 2015, 8(6), 3607-3632; https://doi.org/10.3390/ma8063607
Received: 18 March 2015 / Revised: 2 May 2015 / Accepted: 10 June 2015 / Published: 17 June 2015
Cited by 21 | PDF Full-text (1679 KB) | HTML Full-text | XML Full-text
Abstract
The inhibition of mild steel corrosion in 1 M HCl solution by some ionic liquids (ILs) namely, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate [HMIM][TfO], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4], 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF6], and 1-hexyl-3-methylimidazolium iodide [HMIM][I] was investigated using electrochemical measurements, spectroscopic analyses and quantum
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The inhibition of mild steel corrosion in 1 M HCl solution by some ionic liquids (ILs) namely, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate [HMIM][TfO], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4], 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF6], and 1-hexyl-3-methylimidazolium iodide [HMIM][I] was investigated using electrochemical measurements, spectroscopic analyses and quantum chemical calculations. All the ILs showed appreciably high inhibition efficiency. At 303 K, the results of electrochemical measurements indicated that the studied ILs are mixed-type inhibitors. The adsorption studies showed that all the four ILs adsorb spontaneously on steel surface with [HMIM][TfO], [HMIM][BF4] and [HMIM][I] obeying Langmuir adsorption isotherm, while [HMIM][PF6] conformed better with Temkin adsorption isotherm. Spectroscopic analyses suggested the formation of Fe/ILs complexes. Some quantum chemical parameters were calculated to corroborate experimental results. Full article
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Open AccessArticle Biomimetic Coating on Porous Alumina for Tissue Engineering: Characterisation by Cell Culture and Confocal Microscopy
Materials 2015, 8(6), 3584-3606; https://doi.org/10.3390/ma8063584
Received: 9 March 2015 / Revised: 26 May 2015 / Accepted: 2 June 2015 / Published: 17 June 2015
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Abstract
In this study porous alumina samples were prepared and then coated using the biomimetic coating technique using a five times Simulated Body Fluid (5.0SBF) as the growth solution. A coating was achieved after pre-treatment with concentrated acid. From elemental analysis, the coating contained
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In this study porous alumina samples were prepared and then coated using the biomimetic coating technique using a five times Simulated Body Fluid (5.0SBF) as the growth solution. A coating was achieved after pre-treatment with concentrated acid. From elemental analysis, the coating contained calcium and phosphorous, but also sodium and chlorine. Halite was identified by XRD, a sodium chloride phase. Sintering was done to remove the halite phase. Once halite was burnt off, the calcium phosphate crystals were not covered with halite and, therefore, the apatite phases can be clearly observed. Cell culturing showed sufficient cell attachment to the less porous alumina, Sample B, that has more calcium phosphate growth, while the porous alumina, Sample A, with minimal calcium phosphate growth attained very little cell attachment. This is likely due to the contribution that calcium phosphate plays in the attachment of bone-like cells to a bioinert ceramic such as alumina. These results were repeated on both SEM and confocal microscopy analysis. Confocal microscopy was a novel characterisation approach which gave useful information and was a visual aid. Full article
(This article belongs to the Special Issue Bioceramics)
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Open AccessArticle A New Predictive Model of Centerline Segregation in Continuous Cast Steel Slabs by Using Multivariate Adaptive Regression Splines Approach
Materials 2015, 8(6), 3562-3583; https://doi.org/10.3390/ma8063562
Received: 25 May 2015 / Revised: 4 June 2015 / Accepted: 8 June 2015 / Published: 17 June 2015
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Abstract
The aim of this study was to obtain a predictive model able to perform an early detection of central segregation severity in continuous cast steel slabs. Segregation in steel cast products is an internal defect that can be very harmful when slabs are
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The aim of this study was to obtain a predictive model able to perform an early detection of central segregation severity in continuous cast steel slabs. Segregation in steel cast products is an internal defect that can be very harmful when slabs are rolled in heavy plate mills. In this research work, the central segregation was studied with success using the data mining methodology based on multivariate adaptive regression splines (MARS) technique. For this purpose, the most important physical-chemical parameters are considered. The results of the present study are two-fold. In the first place, the significance of each physical-chemical variable on the segregation is presented through the model. Second, a model for forecasting segregation is obtained. Regression with optimal hyperparameters was performed and coefficients of determination equal to 0.93 for continuity factor estimation and 0.95 for average width were obtained when the MARS technique was applied to the experimental dataset, respectively. The agreement between experimental data and the model confirmed the good performance of the latter. Full article
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Open AccessArticle Preparation of Advanced Carbon Anode Materials from Mesocarbon Microbeads for Use in High C-Rate Lithium Ion Batteries
Materials 2015, 8(6), 3550-3561; https://doi.org/10.3390/ma8063550
Received: 13 May 2015 / Revised: 1 June 2015 / Accepted: 3 June 2015 / Published: 17 June 2015
Cited by 8 | PDF Full-text (2259 KB) | HTML Full-text | XML Full-text
Abstract
Mesophase soft carbon (MSC) and mesophase graphite (SMG), for use in comparative studies of high C-rate Lithium Ion Battery (LIB) anodes, were made by heating mesocarbon microbeads (MCMB) at 1300 °C and 3000 °C; respectively. The crystalline structures and morphologies of the MSC,
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Mesophase soft carbon (MSC) and mesophase graphite (SMG), for use in comparative studies of high C-rate Lithium Ion Battery (LIB) anodes, were made by heating mesocarbon microbeads (MCMB) at 1300 °C and 3000 °C; respectively. The crystalline structures and morphologies of the MSC, SMG, and commercial hard carbon (HC) were investigated by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. Additionally, their electrochemical properties, when used as anode materials in LIBs, were also investigated. The results show that MSC has a superior charging rate capability compared to SMG and HC. This is attributed to MSC having a more extensive interlayer spacing than SMG, and a greater number of favorably-oriented pathways when compared to HC. Full article
(This article belongs to the Special Issue Selected Papers from ICETI2014)
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