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Materials, Volume 12, Issue 12 (June-2 2019)

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Open AccessArticle
Conceptual Design of Composite Sandwich Structure Submarine Radome
Materials 2019, 12(12), 1966; https://doi.org/10.3390/ma12121966 (registering DOI)
Received: 23 May 2019 / Revised: 9 June 2019 / Accepted: 13 June 2019 / Published: 18 June 2019
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Abstract
Radomes are usually constructed from sandwich structures made of materials which usually have a low dielectric constant so that they do not interfere with electromagnetic waves. Performance of the antenna is increased by the appropriate assortment of materials enabling it to survive under [...] Read more.
Radomes are usually constructed from sandwich structures made of materials which usually have a low dielectric constant so that they do not interfere with electromagnetic waves. Performance of the antenna is increased by the appropriate assortment of materials enabling it to survive under marine applications, and it depends on composite strength-to-weight ratio, stiffness, and resistance to corrosion. The design of a sandwich core submarine radome greatly depends on the material system, number of layers, orientation angles, and thickness of the core material. In this paper, a conceptual design study for a sandwich core submarine radome is carried out with the help of finite element analysis (FEA) using two unidirectional composite materials—glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP)—as a skin material and six different core materials. Conceptual designs are obtained based on constraints on the composite materials’ failure, buckling, and strength. The thickness of the core is reduced under constraints on material and buckling strength. Finite element analysis software ANSYS WORKBENCH is used to carry out all the simulations. Full article
(This article belongs to the Section Advanced Composites)
Open AccessArticle
Evolution of Zeolite Crystals in Self-Supporting Faujasite Blocks: Effects of Hydrothermal Conditions
Materials 2019, 12(12), 1965; https://doi.org/10.3390/ma12121965 (registering DOI)
Received: 17 May 2019 / Revised: 14 June 2019 / Accepted: 14 June 2019 / Published: 18 June 2019
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Abstract
In order to prepare self-supporting faujasite (FAU) zeolite, a self-supporting zeolite block was synthesized in situ by hydrothermal treatment of a metakaolin base geopolymer. The effects of hydrothermal conditions such as hydrothermal alkalinity, temperature and time on the phase composition, microstructure and mechanical [...] Read more.
In order to prepare self-supporting faujasite (FAU) zeolite, a self-supporting zeolite block was synthesized in situ by hydrothermal treatment of a metakaolin base geopolymer. The effects of hydrothermal conditions such as hydrothermal alkalinity, temperature and time on the phase composition, microstructure and mechanical strength of the hydrothermal samples were investigated and evidenced by a series of characterization methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmet-Teller (BET). The results showed that a self-supporting faujasite block could be obtained by hydrothermal treatment of the geopolymer block in 2 M NaOH solution at 90 °C for 24 h, which had high crystallinity, regular morphology and high compressive strength. The self-supporting zeolite block had a compressive strength of 11.7 MPa, a pore volume of 0.24 cm3/g, and an average pore diameter of 7.86 nm. The specific surface area and the microporous specific surface area of the self-supporting faujasite blocks were 80.36 m2/g and 19.7 m2/g, respectively. Full article
(This article belongs to the Section Construction and Building Materials)
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Open AccessArticle
The Performance of Super Absorbent Polymer (SAP) Water-Retaining Asphalt Mixture
Materials 2019, 12(12), 1964; https://doi.org/10.3390/ma12121964 (registering DOI)
Received: 28 May 2019 / Revised: 12 June 2019 / Accepted: 14 June 2019 / Published: 18 June 2019
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Abstract
Lowering the temperature of the road surface is one efficient way to alleviate the urban heat island effect. Therefore water-retaining asphalt mixture was produced by adding super absorbent polymer (SAP) containing cement mortar to the porous asphalt mixture. In this study, the water [...] Read more.
Lowering the temperature of the road surface is one efficient way to alleviate the urban heat island effect. Therefore water-retaining asphalt mixture was produced by adding super absorbent polymer (SAP) containing cement mortar to the porous asphalt mixture. In this study, the water absorption capacity, mechanical strength and fluidity of the cured water-retaining mortar were investigated to determine the optimum SAP dosage in water-retaining mortar. Furthermore, the microstructure of the hardened water-retaining mortar was studied using scanning electron microscopy (SEM) to determine the morphology and distribution of SAP in the final product, which may help to understand the influence of SAP on water retention performance and decipher its underlying mechanism. Compared to the raw porous asphalt mixture, the water-retaining asphalt mixture showed good moisture susceptibility (retained stability (RS) ≥ 88.2%, tensile strength ratio (TSR) ≥ 81.8%), good rutting resistance (9336–10,552 times/mm) and low temperature crack resistance (3383–3621 MPa), as well as significant cooling effects (10–12 °C). The results illustrate that the prepared SAP water-retaining asphalt mixture has good potential in reducing dust and enhancing road performance. Full article
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Open AccessArticle
Electromagnetic Sheet Forming by Uniform Pressure Using Flat Spiral Coil
Materials 2019, 12(12), 1963; https://doi.org/10.3390/ma12121963 (registering DOI)
Received: 13 May 2019 / Revised: 10 June 2019 / Accepted: 13 June 2019 / Published: 18 June 2019
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Abstract
The coil is the most important component in electromagnetic forming. Two important questions in electromagnetic forming are how to obtain the desired magnetic force distribution on the sheet and increase the service life of the coil. A uniform pressure coil is widely used [...] Read more.
The coil is the most important component in electromagnetic forming. Two important questions in electromagnetic forming are how to obtain the desired magnetic force distribution on the sheet and increase the service life of the coil. A uniform pressure coil is widely used in sheet embossing, bulging, and welding. However, the coil is easy to break, and the manufacturing process is complex. In this paper, a new uniform-pressure coil with a planar structure was designed. A three-dimensional (3D) finite element model was established to analyze the effect of the main process parameters on magnetic force distribution. By comparing the experimental results, it was found that the simulation results have a higher analysis precision. Based on the simulation results, the resistivity of the die, spacing between the left and right parts of the coil, relative position between coil and sheet, and sheet width significantly affect the distribution of magnetic force. Compared with the structure and magnetic force on a traditional uniform pressure coil, the planar uniform pressure coil can produce a uniform magnetic force distribution on the sheet, reduce the manufacturing difficulty, reduce manufacturing cost, and enhance the service life for the coil. Full article
(This article belongs to the Special Issue Advanced Metal Forming Processes)
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Open AccessArticle
Integrated Dynamic Characterization of Thermorheologically Simple Viscoelastic Materials Accounting for Frequency, Temperature, and Preload Effects
Materials 2019, 12(12), 1962; https://doi.org/10.3390/ma12121962 (registering DOI)
Received: 30 March 2019 / Revised: 14 June 2019 / Accepted: 14 June 2019 / Published: 18 June 2019
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Abstract
In vibration insulation projects, a parameter affecting the dynamic properties of the viscoelastic materials is the previous static load acting on the supports, denominated here as the ‘preload’. Most of the currently-used methodologies obtain the dynamic properties by considering only the effects of [...] Read more.
In vibration insulation projects, a parameter affecting the dynamic properties of the viscoelastic materials is the previous static load acting on the supports, denominated here as the ‘preload’. Most of the currently-used methodologies obtain the dynamic properties by considering only the effects of temperature and frequency. The additional effect of preload can be added to the usual methodologies by employing the hyperelastic theory developed by Mooney–Rivlin. The current work proposes an integrated approach to characterize thermorheologically simple viscoelastic materials, including the preload effect along with the influence of temperature and frequency. The proposed method uses a hybrid optimization process, combining a genetic algorithm (GA) and a non-linear optimization technique—named ‘simplex’—in an inverse problem structure applied to all experimental data at hand. A set of samples of elastomer BT-806 55 (butyl rubber) was tested at various temperatures, frequencies, and preloads. The comparison between the results of the present methodology and traditional approaches to a variation in the dynamic properties at all frequencies and temperatures for a constant vibration amplitude. The present results prove that the proposed methodology is a viable alternative to represent the dynamic properties of materials used in vibration isolation. Full article
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Open AccessArticle
A Hybrid Process Integrating Reverse Engineering, Pre-Repair Processing, Additive Manufacturing, and Material Testing for Component Remanufacturing
Materials 2019, 12(12), 1961; https://doi.org/10.3390/ma12121961 (registering DOI)
Received: 29 May 2019 / Revised: 10 June 2019 / Accepted: 14 June 2019 / Published: 18 June 2019
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Abstract
Metallic components can gain defects such as dents, cracks, wear, heat checks, deformation, etc., that need to be repaired before reinserting into service for extending the lifespan of these parts. In this study, a hybrid process was developed to integrate reverse engineering, pre-repair [...] Read more.
Metallic components can gain defects such as dents, cracks, wear, heat checks, deformation, etc., that need to be repaired before reinserting into service for extending the lifespan of these parts. In this study, a hybrid process was developed to integrate reverse engineering, pre-repair processing, additive manufacturing, and material testing for the purpose of part remanufacturing. Worn components with varied defects were scanned using a 3D scanner to recreate the three-dimensional models. Pre-repair processing methods which include pre-repair machining and heat-treatment were introduced. Strategies for pre-repair machining of defects including surface impact damage, surface superficial damage and cracking were presented. Pre-repair heat-treatment procedure for H13 tool steel which was widely used in die/mold application was introduced. Repair volume reconstruction methodology was developed to regain the missing geometry on worn parts. The repair volume provides a geometry that should be restored in the additive manufacturing process. A damaged component was repaired using the directed energy deposition process to rebuild the worn geometry. The repaired part was inspected in microstructure and mechanical aspects to evaluate the repair. The hybrid process solved key issues associated with repair, providing a solution for automated metallic component remanufacturing. Full article
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Open AccessArticle
Preparation of Sol-Gel Derived Anticorrosive Coating on Q235 Carbon Steel Substrate with Long-Term Corrosion Prevention Durability
Materials 2019, 12(12), 1960; https://doi.org/10.3390/ma12121960 (registering DOI)
Received: 10 May 2019 / Revised: 10 June 2019 / Accepted: 17 June 2019 / Published: 18 June 2019
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Abstract
Anticorrosive coatings prepared by sol-gel derived approaches have become an emergent research area in the field of corrosion prevention materials. Furthermore, enhanced coating thickness can greatly improve the barrier effect of the sol-gel coatings, thus influencing their service life in industrial applications. Here, [...] Read more.
Anticorrosive coatings prepared by sol-gel derived approaches have become an emergent research area in the field of corrosion prevention materials. Furthermore, enhanced coating thickness can greatly improve the barrier effect of the sol-gel coatings, thus influencing their service life in industrial applications. Here, we propose the preparation of a two-layer coating system using a low-cost sol-gel derived method. The coating structure was composed of first an underlying layer incorporated with silica and titania powder as filler and pigment materials, and a second translucent topcoat containing a colloidal silica sol-gel matrix crosslinked by methyltrimethoxysilane (MTMS). This coating system was applied on Q235 carbon steel substrate by a two-step spray deposition method, resulting in an enhanced coating thickness of around 35 μm. The physical and morphological properties of the coatings were characterized using multiple techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The anticorrosion performance of the sol-gel coatings was studied by a salt spray test, outdoor exposure test and electrochemical impedance spectroscopy (EIS). Results revealed that this two-layer coating system exhibited excellent physical and anticorrosion properties, and that the topcoat played a crucial role in maintaining the barrier effect and preventing water leakage. Full article
(This article belongs to the Section Construction and Building Materials)
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Open AccessArticle
Surface Modification of Poly(lactic-co-glycolic acid) Microspheres with Enhanced Hydrophilicity and Dispersibility for Arterial Embolization
Materials 2019, 12(12), 1959; https://doi.org/10.3390/ma12121959 (registering DOI)
Received: 19 May 2019 / Revised: 14 June 2019 / Accepted: 17 June 2019 / Published: 18 June 2019
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Abstract
In this study, a series of poly(lactic-co-glycolic acid) (PLGA) microspheres with different particle sizes for arterial embolization surgery were prepared. The polydopamine (PDA) and polydopamine/polyethyleneimine (PDA/PEI) were respectively coated on the PLGA microspheres as shells, in order to improve the hydrophilicity and dispersibility [...] Read more.
In this study, a series of poly(lactic-co-glycolic acid) (PLGA) microspheres with different particle sizes for arterial embolization surgery were prepared. The polydopamine (PDA) and polydopamine/polyethyleneimine (PDA/PEI) were respectively coated on the PLGA microspheres as shells, in order to improve the hydrophilicity and dispersibility of PLGA embolization microspheres. After modification, with the introduction of PDA and PEI, many hydrophilic hydroxyl and amine groups appeared on the surface of the [email protected] and [email protected]/PEI microspheres. SEM images showed the morphologies, sizes, and changes of the as-prepared microspheres. Meanwhile, the XPS and FT-IR spectra demonstrated the successful modification of the PDA and PEI. Water contact angles (WCAs) of the [email protected] and [email protected]/PEI microspheres became smaller, indicating a certain improvement in surface hydrophilicity. In addition, the results of in vitro cytotoxicity showed that modification had little effect on the biosafety of the microspheres. The modified PLGA microspheres suggest a promising prospective application in biomedical field, as the modified microspheres can reduce difficulties in embolization surgery. Full article
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Open AccessArticle
Evaluation of the Accuracy of Four Digital Methods by Linear and Volumetric Analysis of Dental Impressions
Materials 2019, 12(12), 1958; https://doi.org/10.3390/ma12121958 (registering DOI)
Received: 12 April 2019 / Revised: 12 June 2019 / Accepted: 13 June 2019 / Published: 18 June 2019
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Abstract
The quality of dental arch impression has a substantial role in the precision of the intervention. It is traditionally acquired with resins that solidify when in contact with the air. Compared to that method, digital impression gives great advantages and, together with three-dimensional [...] Read more.
The quality of dental arch impression has a substantial role in the precision of the intervention. It is traditionally acquired with resins that solidify when in contact with the air. Compared to that method, digital impression gives great advantages and, together with three-dimensional (3D) digitization devices, allows a simplification of the digital impression process. The growing adoption of such systems by a large number of dental clinics determines the need for an in-depth evaluation of the accuracy and the precision of the different systems. The aim of this work is to define a methodology for the evaluation of the accuracy and precision of 3D intraoral and desktop scanning systems, by using volumetric and linear methods. The replica of a tooth was realized with zirconium; afterward, high-accuracy point clouds of the master model were acquired by a coordinate measurement machine (CMM). In this way, the dimensions of the replica were accurately known. An intraoral scanner (I) and three desktops (D1, D2, D3) were then used to scan the replica. The geometry resulting from the CMM was compared with the ones derived from the scanners, using two different commercial programs (Geomagic and 3-Matic) and a custom-developed algorithm (MATLAB). Geomagic showed the mean values to be in a range from 0.0286 mm (D1) to 0.1654 mm (I), while 3-Matic showed mean values from −0.0396 mm (D1) to 0.1303 mm (I). MATLAB results ranged from 0.00014 mm (D1) to 0.00049 mm (D2). The probability distributions of the volumetric error of the measurements obtained with the different scanners allow a direct comparison of their performances. For the results given by our study, the volumetric approach that we adopted appears to be an excellent system of analysis. Full article
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Open AccessArticle
Design, Synthesis, Structure and Properties of Ba-Doped Derivatives of SrCo0.95Ru0.05O3−δ Perovskite as Cathode Materials for SOFCs
Materials 2019, 12(12), 1957; https://doi.org/10.3390/ma12121957 (registering DOI)
Received: 29 May 2019 / Revised: 11 June 2019 / Accepted: 13 June 2019 / Published: 18 June 2019
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Abstract
We have designed and prepared a novel cathode material for solid oxide fuel cell (SOFC) based on SrCo0.95Ru0.05O3−δ perovskite. We have partially replaced Sr by Ba in Sr0.9Ba0.1Co0.95Ru0.05O3−δ (SBCRO) [...] Read more.
We have designed and prepared a novel cathode material for solid oxide fuel cell (SOFC) based on SrCo0.95Ru0.05O3−δ perovskite. We have partially replaced Sr by Ba in Sr0.9Ba0.1Co0.95Ru0.05O3−δ (SBCRO) in order to expand the unit-cell size, thereby improving the ionic diffusion of O2− through the crystal lattice. The characterization of this new oxide has been studied at room temperature by X-ray diffraction (XRD) and neutron powder diffraction (NPD) experiments. At room temperature, SBCRO perovskite crystallizes in the P4/mmm tetragonal space group, as observed from NDP data. The maximum conductivity value of 18.6 S cm−1 is observed at 850 °C. Polarization resistance measurements on LSGM electrolyte demonstrate an improvement in conductivity with respect to the parent Sr-only perovskite cathode. A good chemical compatibility and an adequate thermal expansion coefficient make this oxide auspicious for using it as a cathode in SOFC. Full article
(This article belongs to the Special Issue Solid State Materials for Energy Applications)
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Open AccessArticle
Novel Ni/pHEMA-gr-PVP Composites Obtained by Polymerization with Simultaneous Metal Deposition: Structure and Properties
Materials 2019, 12(12), 1956; https://doi.org/10.3390/ma12121956 (registering DOI)
Received: 28 May 2019 / Revised: 14 June 2019 / Accepted: 17 June 2019 / Published: 18 June 2019
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Abstract
The synthesis and study of metal-containing hydrogels, particularly those filled with nickel nanoparticles, is currently of interest to many researchers. This paper presents the results of an investigation of the structure and properties of Ni(0)-filled composites on the basis of 2-hydroxyethylmethacrylate copolymers (HEMA) [...] Read more.
The synthesis and study of metal-containing hydrogels, particularly those filled with nickel nanoparticles, is currently of interest to many researchers. This paper presents the results of an investigation of the structure and properties of Ni(0)-filled composites on the basis of 2-hydroxyethylmethacrylate copolymers (HEMA) with polyvinylpyrrolidone (PVP) and their hydrogels. The authors of the article are the first who propose the method to produce these materials by combining the processes of polymer matrix synthesis and a reduction of Ni2+ ions. Synthesis is carried out in one stage without complicated equipment and is technologically simple. It is determined by thermometric research that the temperature conditions required for the chemical reduction of Ni2+ are achieved due to the heat released during the exothermic reaction of HEMA polymerization in the presence of PVP. With the help of Fourier transform infrared analysis, and thermogravimetric and differential-thermal analysis, the formation of a crosslinked graft copolymer based on HEMA and PVP was confirmed, and its structural parameters, including the efficiency of PVP grafting, PVP content in the copolymer, and the molecular weight of the interstitial fragment of the polymer network, were investigated. The results obtained with scanning electron microscopy revealed that the size of the Ni(0) particles is about 500 nm. X-ray structural analysis of the composites obtained confirmed the existence of metal nickel particles. The strength, elastic, sorption, electrical, and magnetic properties of the obtained composites in the solid (dry) and elastic (swollen) physical states, depending on the composition of the copolymer and the content of the metal filler, have been investigated. Full article
(This article belongs to the Section Advanced Composites)
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Open AccessArticle
Investigation of Cutting Force in Longitudinal-Torsional Ultrasonic-Assisted Milling of Ti-6Al-4V
Materials 2019, 12(12), 1955; https://doi.org/10.3390/ma12121955
Received: 31 May 2019 / Revised: 13 June 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
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Abstract
In this study, we propose a longitudinal-torsion ultrasonic-assisted milling (LTUM) machining method for difficult-to-cut materials—such as titanium alloy—in order to realize anti-fatigue manufacturing. In addition, a theoretical prediction model of cutting force is established. To achieve this, we used the cutting edge trajectory [...] Read more.
In this study, we propose a longitudinal-torsion ultrasonic-assisted milling (LTUM) machining method for difficult-to-cut materials—such as titanium alloy—in order to realize anti-fatigue manufacturing. In addition, a theoretical prediction model of cutting force is established. To achieve this, we used the cutting edge trajectory of LTUM to reveal the difference in trajectory between LTUM and traditional milling (TM). Then, an undeformed chip thickness (UCT) model of LTUM was constructed. From this, the cutting force model was able to be established. A series of experiments were subsequently carried out to verify this LTUM cutting force model. Based on the established model, the influence of several parameters on cutting force was analyzed. The results showed that the established theoretical model of cutting force was in agreement with the experimental results, and that, compared to TM, the cutting force was lower in LTUM. Specifically, the cutting force in the feed direction, Fx, decreased by 24.8%, while the cutting force in the width of cut direction Fy, decreased by 29.9%. Full article
Open AccessArticle
The Preparation and Chemical Structure Analysis of Novel POSS-Based Porous Materials
Materials 2019, 12(12), 1954; https://doi.org/10.3390/ma12121954
Received: 20 April 2019 / Revised: 10 June 2019 / Accepted: 11 June 2019 / Published: 17 June 2019
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Abstract
In this work, we reported the preparation and chemical analysis of novel polyhedral oligomeric silsesquioxane (POSS)-based porous materials, which were prepared according to Friedel-Crafts chloromethylation by using aluminum chloride as the catalyst and dichloromethane as the solvent. Through controlling the treatment solvent (water [...] Read more.
In this work, we reported the preparation and chemical analysis of novel polyhedral oligomeric silsesquioxane (POSS)-based porous materials, which were prepared according to Friedel-Crafts chloromethylation by using aluminum chloride as the catalyst and dichloromethane as the solvent. Through controlling the treatment solvent (water or methanol) and kinds of POSS, several materials with different morphologies were conveniently obtained. The chemical structure of porous materials was systematically characterized by Fourier-transform infrared (FTIR) spectra, 29Si Nuclear Magnetic Resonance (NMR), 13C NMR, and X-ray photoelectron spectroscopy (XPS). The samples were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to study their crystallinity, morphology, and thermal properties, respectively. The work systematically demonstrated the chemical structure of the porous materials. Moreover, the advantages and disadvantages of the preparation method and typical properties of the material were evaluated through a comparative analysis with other related research works. Full article
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Open AccessArticle
Expandable Layered Hybrid Materials Based on Individual 1D Metalorganic Nanoribbons
Materials 2019, 12(12), 1953; https://doi.org/10.3390/ma12121953
Received: 24 May 2019 / Revised: 12 June 2019 / Accepted: 13 June 2019 / Published: 17 June 2019
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Abstract
Different metalorganic lamellar hybrid materials based on associated nanoribbons were synthesized by the use of alkyl–benzyl monocarboxylate spacers, containing alkyl tails with variable lengths, which acted like structural growing inhibitors. These molecular agents were perpendicularly located and coordinated to aluminium nodes in the [...] Read more.
Different metalorganic lamellar hybrid materials based on associated nanoribbons were synthesized by the use of alkyl–benzyl monocarboxylate spacers, containing alkyl tails with variable lengths, which acted like structural growing inhibitors. These molecular agents were perpendicularly located and coordinated to aluminium nodes in the interlayer space, controlling the separation between individual structure sub-units. The hybrid materials were studied by X-ray diffraction (XRD), chemical and thermogravimetrical analysis (TGA), nuclear magnetic resonance (NMR) and infrared spectroscopy (IR), and field emission scanning electron microscopy (FESEM)/transmission electron microscopy (TEM), showing their physicochemical properties. The specific capacity of the metalorganic materials to be exfoliated through post-synthesis treatments, using several solvents due to the presence of 1D structure sub-units and a marked hydrophobic nature, was also evidenced. Full article
(This article belongs to the Special Issue Advances in Metal Organic Framework Materials)
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Open AccessReview
Electrode Materials for High-Performance Sodium-Ion Batteries
Materials 2019, 12(12), 1952; https://doi.org/10.3390/ma12121952
Received: 1 May 2019 / Revised: 6 June 2019 / Accepted: 7 June 2019 / Published: 17 June 2019
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Abstract
Sodium ion batteries (SIBs) are being billed as an economical and environmental alternative to lithium ion batteries (LIBs), especially for medium and large-scale stationery and grid storage. However, SIBs suffer from lower capacities, energy density and cycle life performance. Therefore, in order to [...] Read more.
Sodium ion batteries (SIBs) are being billed as an economical and environmental alternative to lithium ion batteries (LIBs), especially for medium and large-scale stationery and grid storage. However, SIBs suffer from lower capacities, energy density and cycle life performance. Therefore, in order to be more efficient and feasible, novel high-performance electrodes for SIBs need to be developed and researched. This review aims to provide an exhaustive discussion about the state-of-the-art in novel high-performance anodes and cathodes being currently analyzed, and the variety of advantages they demonstrate in various critically important parameters, such as electronic conductivity, structural stability, cycle life, and reversibility. Full article
(This article belongs to the Special Issue Electrode Materials for High Performance Sodium-ion Batteries)
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Open AccessArticle
The Effect of Cellulose Nanocrystal Coatings on the Glass Fiber–Epoxy Interphase
Materials 2019, 12(12), 1951; https://doi.org/10.3390/ma12121951
Received: 27 May 2019 / Revised: 7 June 2019 / Accepted: 11 June 2019 / Published: 17 June 2019
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Abstract
This study focuses on understanding the effect of cellulose nanocrystals (CNCs) on glass fiber/epoxy interfacial interactions. The glass fibers (GF) were coated with solutions containing cellulose nanomaterial. The parameters that were investigated were the CNC surface chemistry, concentration, and dispersing medium, i.e., aqueous [...] Read more.
This study focuses on understanding the effect of cellulose nanocrystals (CNCs) on glass fiber/epoxy interfacial interactions. The glass fibers (GF) were coated with solutions containing cellulose nanomaterial. The parameters that were investigated were the CNC surface chemistry, concentration, and dispersing medium, i.e., aqueous solution only versus emulsions. To determine the effect of the CNC coatings on the interfacial adhesion, specimens of a single GF in an epoxy matrix were prepared for GF coating by varying the coating formulations. The interfacial shear stress (IFSS) was determined by the single fiber fragmentation test (SFFT). Following the SFFT, the samples were investigated by cross-polarized microscopy in order to understand the fracture modes which are related to the nature of the interphase. According to the SFFT data and photoelastic fracture patterns, both the emulsion and aqueous coatings containing cellulose nanocrystals functionalized with methyl(triphenyl) phosphonium (CNCPh) improve the IFSS in comparison to coated GFs without CNCs. Full article
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Open AccessArticle
In-Situ Growth of Au on KTaO3 Sub-Micron Cubes via Wet Chemical Approach for Enhanced Photodegradation of p-Nitrophenol
Materials 2019, 12(12), 1950; https://doi.org/10.3390/ma12121950
Received: 30 April 2019 / Revised: 11 June 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
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Abstract
KTaO3/Au hetero-nanostructures were synthesized by in-situ reduction of HAuCl4 on the surface of hydrothermally-grown KTaO3 sub-micron cubes. The concentration of Au source was found to be a critical factor in controlling the hetero-nucleation of Au nanoparticles on the surface [...] Read more.
KTaO3/Au hetero-nanostructures were synthesized by in-situ reduction of HAuCl4 on the surface of hydrothermally-grown KTaO3 sub-micron cubes. The concentration of Au source was found to be a critical factor in controlling the hetero-nucleation of Au nanoparticles on the surface of KTaO3 sub-micron cubes. Loading of Au particles on KTaO3 nanocrystals enriched KTaO3 additional UV-vis absorption in the visible light region. Both KTaO3 and KTaO3/Au nanocrystals were shown to be active in the photo-degradation of p-nitrophenol, while the loading of Au on KTaO3 clearly improved the photo-degradation efficiency of p-nitrophenol compared to that on bare KTaO3 nanocrystals, probably due to the improved light absorption and charge separation. Full article
(This article belongs to the Special Issue Novel In Situ Synthesis of Advanced Functional Materials)
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Open AccessArticle
A Comparison Study of Ag Composites Prepared by Spark Plasma Sintering and Hot Pressing with Silver-Coated CNTs as the Reinforcements
Materials 2019, 12(12), 1949; https://doi.org/10.3390/ma12121949
Received: 21 May 2019 / Revised: 9 June 2019 / Accepted: 11 June 2019 / Published: 17 June 2019
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Abstract
In this study, carbon nanotube-reinforced silver composites (CNT/Ag) were prepared by the powder metallurgy process via spark plasma sintering (SPS) and hot pressing sintering (HP) with composite powders through an improved electroless plating method assisted by ultrasonic spray atomization. The dispersion of CNTs [...] Read more.
In this study, carbon nanotube-reinforced silver composites (CNT/Ag) were prepared by the powder metallurgy process via spark plasma sintering (SPS) and hot pressing sintering (HP) with composite powders through an improved electroless plating method assisted by ultrasonic spray atomization. The dispersion of CNTs was effectively improved by ultrasonic spray atomization, and uniform silver layers were deposited on the surface of CNTs by electroless deposition. The property testing results showed significant improvements of the electrical conductivity, hardness, and tensile strength in the samples prepared by SPS, as compared to their HP sintered counterparts. When the volume fraction of CNTs reached 2.5%, the tensile strength reached a maximum value of 221 MPa, which was more than twice that of the pure silver samples. The structural analysis indicated different degrees of CNT agglomeration and matrix mean grain sizes in the composites prepared by SPS and HP, which are responsible for the differences in properties. Full article
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Open AccessArticle
Effects of Bi2O3 Doping on the Mechanical Properties of PbO Ceramic Pellets Used in Lead-Cooled Fast Reactors
Materials 2019, 12(12), 1948; https://doi.org/10.3390/ma12121948
Received: 24 April 2019 / Revised: 12 June 2019 / Accepted: 12 June 2019 / Published: 17 June 2019
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Abstract
In this paper, the effects of Bi2O3 doping on the mechanical properties of PbO ceramic pellets were studied. Different ratios of Bi2O3/PbO (i.e., xBi2O3-(1−x) PbO, where x is 0, [...] Read more.
In this paper, the effects of Bi2O3 doping on the mechanical properties of PbO ceramic pellets were studied. Different ratios of Bi2O3/PbO (i.e., xBi2O3-(1−x) PbO, where x is 0, 1, 3, 5, or 7 wt.%) were fabricated and sintered at 570, 620, and 670 °C. Mechanical properties including density, hardness, flexural strength, and sintering of PbO were studied for each of the aforementioned compositions. Phase composition, microstructure, and the worn surfaces of the composites were characterized by scanning electron microscopy and X-ray diffraction (XRD). The XRD analysis revealed that a solid solution formed in the composite ceramic. The best suited conditions of temperature and doping of Bi2O3 for optimal sintering were found to be 620 °C and 3 wt.%, respectively. The hardness of the 3 wt.% Bi2O3-97 wt.% PbO ceramic was found to be 717 MPa, which is about four times higher than the hardness of pure PbO. In addition, the strength of the composites was found to be 43 MPa, which is two times higher than that of pure PbO. The integrity of the composites was verified using the lead–bismuth eutectic alloy flushing experiment. The results of this research paper are important for future studies of oxygen control in the lead–bismuth eutectic alloy of lead-cooled fast reactors. Full article
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Open AccessArticle
Effect of Oxygen Concentration and Tantalum Addition on the Formation of High Temperature Bismuth Oxide Phase by Mechanochemical Reaction
Materials 2019, 12(12), 1947; https://doi.org/10.3390/ma12121947
Received: 18 May 2019 / Revised: 10 June 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
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Abstract
High-temperature face-centered cubic bismuth oxide phase is a material of great interest given its unique properties. In the present study, α-Bi2O3 and tantalum powders were used as the starting powders for the formation of high-temperature bismuth oxide phase via mechanochemical [...] Read more.
High-temperature face-centered cubic bismuth oxide phase is a material of great interest given its unique properties. In the present study, α-Bi2O3 and tantalum powders were used as the starting powders for the formation of high-temperature bismuth oxide phase via mechanochemical synthesis by high energy ball milling. (Bi2O3)80(Ta)20 and (Bi2O3)95(Ta)5 in weight concentrations were milled in either an oxygen-free argon-filled glove box environment or an ambient atmosphere to investigate the effects of oxygen concentration and tantalum addition. The as-milled powders were examined using X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, and differential scanning calorimetry to reveal the structural evolution. The experimental results showed that for (Bi2O3)95(Ta)5 powder mixtures milled within the glove box, tantalum gradually reacted with the α-Bi2O3 phase and formed a β-Bi7.8Ta0.2O12.2 phase. For (Bi2O3)80(Ta)20 milled under the same conditions, Ta and α-Bi2O3 mechanochemically reacted to form δ-Bi3TaO7 and bismuth after 10 min of high energy ball milling, whereas milling (Bi2O3)80(Ta)20 under the ambient atmosphere with a much higher oxygen concentration accelerated the mechanochemical reaction to less than five minutes of milling and resulted in the formation of high-temperature δ-Bi3TaO7 phase. Full article
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Open AccessArticle
Surface Chemical Changes of Sugar Maple Wood Induced by Thermo-Hygromechanical (THM) Treatment
Materials 2019, 12(12), 1946; https://doi.org/10.3390/ma12121946
Received: 21 May 2019 / Revised: 11 June 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
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Abstract
The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. The THM densification process was performed at two different temperatures (180 °C and 200 °C) with and without steam. [...] Read more.
The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. The THM densification process was performed at two different temperatures (180 °C and 200 °C) with and without steam. The functional groups, surface chemical composition and internal structure and components of the control and densified samples were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray photoelectron (XPS) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The obtained results suggest that the THM densification treatment resulted in significant chemical changes on the wood surface. The results of the ATR-FTIR spectra confirmed the decomposition of hemicelluloses and the relative increase of cellulose and lignin contents on the wood surface. The Py-GC/MS and XPS results show an increase of the oxygen/carbon atomic (O/C) ratio, which indicated that chemical substances containing oxygenated functionality were formed through the densification process. The densification treatment favored the depolymerization of hemicelluloses and cellulose as indicated by an increased anhydrous sugar (levoglucosan) release during the pyrolysis process. Densification also facilitated the cleavage of the lignin side chains, resulting in increased phenyl units with short chains released during the pyrolysis process. Full article
(This article belongs to the Section Construction and Building Materials)
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Open AccessArticle
A Combined Barite–Ilmenite Weighting Material to Prevent Barite Sag in Water-Based Drilling Fluid
Materials 2019, 12(12), 1945; https://doi.org/10.3390/ma12121945
Received: 18 May 2019 / Revised: 10 June 2019 / Accepted: 13 June 2019 / Published: 17 June 2019
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Abstract
Barite sag is a serious problem encountered while drilling high-pressure/high-temperature (HPHT) wells. It occurs when barite particles separate from the base fluid leading to variations in drilling fluid density that may cause a serious well control issue. However, it occurs in vertical and [...] Read more.
Barite sag is a serious problem encountered while drilling high-pressure/high-temperature (HPHT) wells. It occurs when barite particles separate from the base fluid leading to variations in drilling fluid density that may cause a serious well control issue. However, it occurs in vertical and inclined wells under both static and dynamic conditions. This study introduces a combined barite–ilmenite weighting material to prevent the barite sag problem in water-based drilling fluid. Different drilling fluid samples were prepared by adding different percentages of ilmenite (25, 50, and 75 wt.% from the total weight of the weighting agent) to the base drilling fluid (barite-weighted). Sag tendency of the drilling fluid samples was evaluated under static and dynamic conditions to determine the optimum concentration of ilmenite which was required to prevent the sag issue. A static sag test was conducted under both vertical and inclined conditions. The effect of adding ilmenite to the drilling fluid was evaluated by measuring fluid density and pH at room temperature, and rheological properties at 120 °F and 250 °F. Moreover, a filtration test was performed at 250 °F to study the impact of adding ilmenite on the drilling fluid filtration performance and sealing properties of the formed filter cake. The results of this study showed that adding ilmenite to barite-weighted drilling fluid increased fluid density and slightly reduced the pH within the acceptable pH range (9–11). Ilmenite maintained the rheology of the drilling fluid with a minimal drop in rheological properties due to the HPHT conditions, while a significant drop was observed for the base fluid (without ilmenite). Adding ilmenite to the base drilling fluid significantly reduced sag factor and 50 wt.% ilmenite was adequate to prevent solids sag in both dynamic and static conditions with sag factors of 0.33 and 0.51, respectively. Moreover, HPHT filtration results showed that adding ilmenite had no impact on filtration performance of the drilling fluid. The findings of this study show that the combined barite–ilmenite weighting material can be a good solution to prevent solids sag issues in water-based fluids; thus, drilling HPHT wells with such fluids would be safe and effective. Full article
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Open AccessArticle
X-ray Computed Tomography for Characterization of Expanded Polystyrene (EPS) Foam
Materials 2019, 12(12), 1944; https://doi.org/10.3390/ma12121944
Received: 28 May 2019 / Revised: 14 June 2019 / Accepted: 15 June 2019 / Published: 17 June 2019
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Abstract
Expanded polystyrene (EPS) foam is widely used in building and construction applications for thermal and acoustic insulation. This material is nearly transparent for X-rays, making it difficult to characterize its pore structure in 3D with X-ray tomography. Because of this difficulty, the pore [...] Read more.
Expanded polystyrene (EPS) foam is widely used in building and construction applications for thermal and acoustic insulation. This material is nearly transparent for X-rays, making it difficult to characterize its pore structure in 3D with X-ray tomography. Because of this difficulty, the pore network is often not investigated and is, thus, poorly known. Since this network controls different physical properties, such as the sound absorption, it is crucial to understand its overall structure. In this manuscript, we show how to reveal the pore network of EPS foams through the combination of high resolution X-ray tomography (micro-CT) and saturation techniques. The foams were saturated with CsCl-brine, which acts as a contrasting agent in X-ray micro-CT imaging. This allowed us to separate the beads, making up the foam, from the pore network. Based on the 3D micro-CT results, we were able to assess a representative elementary volume for the polystyrene, which allows for calculating the acoustical parameters from the Johnson–Champoux–Allard (JCA) model, the pore and bead size distribution. The 3D data was also used as input to simulate sound absorption curves. The parametric study showed that an increase in the bead size influenced the sound absorption of the material. We showed that, by doubling the diameter of beads, the absorption coefficient was doubled in certain ranges of frequency. Full article
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Open AccessReview
Si-Based Materials for Thermoelectric Applications
Materials 2019, 12(12), 1943; https://doi.org/10.3390/ma12121943
Received: 21 May 2019 / Revised: 13 June 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
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Abstract
Si-based thermoelectric materials have attracted attention in recent decades with their advantages of low toxicity, low production costs, and high stability. Here, we report recent achievements on the synthesis and characterization of Si-based thermoelectric materials. In the first part, we show that bulk [...] Read more.
Si-based thermoelectric materials have attracted attention in recent decades with their advantages of low toxicity, low production costs, and high stability. Here, we report recent achievements on the synthesis and characterization of Si-based thermoelectric materials. In the first part, we show that bulk Si synthesized through a natural nanostructuring method exhibits an exceptionally high thermoelectric figure of merit zT value of 0.6 at 1050 K. In the second part, we show the synthesis and characterization of nanocomposites of Si and metal silicides including CrSi2, CoSi2, TiSi2, and VSi2. These are synthesized by the rapid-solidification melt-spinning (MS) technique. Through MS, we confirm that silicide precipitates are dispersed homogenously in the Si matrix with desired nanoscale sizes. In the final part, we show a promising new metal silicide of YbSi2 for thermoelectrics, which exhibits an exceptionally high power factor at room temperature. Full article
(This article belongs to the Special Issue Selected Papers from ISCTA 2018)
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Open AccessArticle
Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition
Materials 2019, 12(12), 1942; https://doi.org/10.3390/ma12121942
Received: 1 May 2019 / Revised: 10 June 2019 / Accepted: 12 June 2019 / Published: 17 June 2019
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Abstract
One of the main by-products of brown coal burning is calcareous fly ash (CFA). Apart from other applications, it is used as a main component of cement, or as an active mineral additive to concrete. The present study involves the impact of the [...] Read more.
One of the main by-products of brown coal burning is calcareous fly ash (CFA). Apart from other applications, it is used as a main component of cement, or as an active mineral additive to concrete. The present study involves the impact of the raw and processed calcareous fly ash (CFA) on the changes of rheological properties of mortars. The said impact was determined by using the coefficient of variation (CV) given in percentage. CFA samples collected from various sources were subjected to testing. The samples were collected from two electrofilters of blocks with boilers of different combustion parameters and from the retention tanks of the CFA sales department (CFA T) in which CFAs from various boilers are mixed. It has been demonstrated that the degree of the impact of CFA addition on the rheological properties of mortars depends on the source of this addition and on bulk density. The present work demonstrates the negative impact of raw CFA on mortar workability, and hence it is questionable to support its use in concrete technology. Full article
(This article belongs to the Section Construction and Building Materials)
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Open AccessArticle
In Situ Study on Fracture Behavior of Z-Pinned Carbon Fiber-Reinforced Aluminum Matrix Composite via Scanning Electron Microscope (SEM)
Materials 2019, 12(12), 1941; https://doi.org/10.3390/ma12121941
Received: 30 April 2019 / Revised: 30 May 2019 / Accepted: 31 May 2019 / Published: 17 June 2019
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Abstract
Inside a scanning electron microscope (SEM) chamber, we performed an in situ interlaminar shear test on a z-pinned carbon fiber-reinforced aluminum matrix composite (Cf/Al) fabricated by the pressure the infiltration method to understand its failure mechanism. Experiments show that introducing a stainless-steel z-pin [...] Read more.
Inside a scanning electron microscope (SEM) chamber, we performed an in situ interlaminar shear test on a z-pinned carbon fiber-reinforced aluminum matrix composite (Cf/Al) fabricated by the pressure the infiltration method to understand its failure mechanism. Experiments show that introducing a stainless-steel z-pin increases the interlaminar shear strength of Cf/Al composite by 148%. The increase in interlaminar shear strength is attributed to the high strength of the stainless-steel z-pin and the strong bonding between the z-pin and the matrix. When the z-pin/matrix interface failed, the z-pin can still experience large shear deformation, thereby enhancing delamination resistance. The failure mechanism of composite includes interfacial debonding, aluminum plough, z-pin shear deformation, frictional sliding, and fracture. These results in this study will help us understand the interlaminar strengthening mechanism of z-pins in the delamination of metal matrix composites. Full article
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Open AccessArticle
Evaluating Material’s Interaction in Wire Electrical Discharge Machining of Stainless Steel (304) for Simultaneous Optimization of Conflicting Responses
Materials 2019, 12(12), 1940; https://doi.org/10.3390/ma12121940
Received: 25 April 2019 / Revised: 13 May 2019 / Accepted: 3 June 2019 / Published: 17 June 2019
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Abstract
Stainless steel (SS 304) is commonly employed in industrial applications due to its considerable corrosion resistance, thermal resistance, and ductility. Most of its intended applications require the formation of complex profiles, which justify the use of wire electrical discharge machining (WEDM). However, its [...] Read more.
Stainless steel (SS 304) is commonly employed in industrial applications due to its considerable corrosion resistance, thermal resistance, and ductility. Most of its intended applications require the formation of complex profiles, which justify the use of wire electrical discharge machining (WEDM). However, its high thermal resistance imposes a limitation on acquiring adequate surface topography because of the high surface tension of the melt pool, which leads to the formation of spherical modules; ultimately, this compromises the surface quality. Furthermore, the stochastic nature of the process makes it difficult to optimize its performance, especially if more than one conflicting response is involved, such as high cutting speed with low surface roughness and kerf width. Therefore, this study aimed to comprehensively investigate the interaction of SS 304 and WEDM, with a prior focus on simultaneously optimizing all the conflicting responses using the Taguchi-based grey relational approach. Analysis of variance (ANOVA) revealed that the current was the most significant parameter for cutting speed and kerf, whereas roughness, voltage (45%), drum speed (25.8%), and nozzle offset distance (~21%) were major contributing factors. SEM micrographs showed that optimal settings not only ensured simultaneous optimization of the conflicting responses but also reduced the number and size of spherical modules. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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Open AccessArticle
Structural Change in Ni-Fe-Ga Magnetic Shape Memory Alloys after Severe Plastic Deformation
Materials 2019, 12(12), 1939; https://doi.org/10.3390/ma12121939
Received: 13 April 2019 / Revised: 13 June 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
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Abstract
Severe plastic deformation (SPD) is widely considered to be the most efficient process in obtaining ultrafine-grained bulk materials. The aim of this study is to examine the effects of the SPD process on Ni-Fe-Ga ferromagnetic shape memory alloys (FSMA). High-speed high-pressure torsion (HSHPT) [...] Read more.
Severe plastic deformation (SPD) is widely considered to be the most efficient process in obtaining ultrafine-grained bulk materials. The aim of this study is to examine the effects of the SPD process on Ni-Fe-Ga ferromagnetic shape memory alloys (FSMA). High-speed high-pressure torsion (HSHPT) was applied in the as-cast state. The exerted key parameters of deformation are described. Microstructural changes, including morphology that were the result of processing, were investigated by optical and scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to study the two-phase microstructure of the alloys. The influence of deformation on microstructural features, such as martensitic plates, intragranular γ phase precipitates, and grain boundaries’ dependence of the extent of deformation is disclosed by transmission electron microscopy. Moreover, the work brings to light the influence of deformation on the characteristics of martensitic transformation (MT). Vickers hardness measurements were carried out on disks obtained by SPD so as to correlate the hardness with the microstructure. The method represents a feasible alternative to obtain ultrafine-grained bulk Ni-Fe-Ga alloys. Full article
(This article belongs to the Special Issue High-Pressure Materials)
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Open AccessArticle
Impact Compression Test and Numerical Simulation Analysis of Concrete after Thermal Treatment in Complex Stress State
Materials 2019, 12(12), 1938; https://doi.org/10.3390/ma12121938
Received: 21 May 2019 / Revised: 11 June 2019 / Accepted: 13 June 2019 / Published: 16 June 2019
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Abstract
To study the dynamic mechanical properties and fracture law of concrete after thermal treatment and reveal its mechanism, the impact compression test was carried out on different thermal-treated (400–800 °C) concrete specimens using a split Hopkinson pressure bas (SHPB) system. By using ANSYS/LS-DYNA, [...] Read more.
To study the dynamic mechanical properties and fracture law of concrete after thermal treatment and reveal its mechanism, the impact compression test was carried out on different thermal-treated (400–800 °C) concrete specimens using a split Hopkinson pressure bas (SHPB) system. By using ANSYS/LS-DYNA, the finite element numerical simulation of the test process was illustrated. The research showed that under passive confining pressure, the more the loading rate is increased, the more obvious the effect of the passive confining pressure on the concrete specimen, as well as the more significant the improvement of the peak stress compared with the uniaxial test. On the other hand, as the temperature damage effect is enhanced, the increase in the material strength at different loading rates is reduced. Numerical simulations showed that in a uniaxial test, as the impact rate increases, the crack initiation time advances, and the degree of fracture increases at the same rate as that of the loading time. In the case of confining pressure, the stress gradually decreases to the edge from the center, and has a significant circumferential diffusion characteristic. The circumferential restraint of the passive confining pressure limits the radial deformation ability of the material to a certain extent, thereby increasing the axial compressive strength. In the analysis of the crushing process of concrete specimens, it was found that the fracture form showed a strong rate dependence. When the loading rate is low, the fracture form is a cleavage-like failure. As the loading rate increases, the fracture form changes to crush failure. The research results provide the necessary theoretical basis for the safety assessment, reinforcement, and maintenance of concrete structures after fire. Full article
(This article belongs to the Section Construction and Building Materials)
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Open AccessArticle
Investigation of Tool Wear and Chip Morphology in Dry Trochoidal Milling of Titanium Alloy Ti–6Al–4V
Materials 2019, 12(12), 1937; https://doi.org/10.3390/ma12121937
Received: 21 May 2019 / Revised: 9 June 2019 / Accepted: 14 June 2019 / Published: 16 June 2019
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Abstract
Titanium alloys are widely used in the manufacture of aircraft and aeroengine components. However, tool wear is a serious concern in milling titanium alloys, which are known as hard-to-cut materials. Trochoidal milling is a promising technology for the high-efficiency machining of hard-to-cut materials. [...] Read more.
Titanium alloys are widely used in the manufacture of aircraft and aeroengine components. However, tool wear is a serious concern in milling titanium alloys, which are known as hard-to-cut materials. Trochoidal milling is a promising technology for the high-efficiency machining of hard-to-cut materials. Aiming to realize green machining titanium alloy, this paper investigates the effects of undeformed chip thickness on tool wear and chip morphology in the dry trochoidal milling of titanium alloy Ti–6Al–4V. A tool wear model related to the radial depth of cut based on the volume of material removed (VMR) is established for trochoidal milling, and optimized cutting parameters in terms of cutting speed and axial depth of cut are selected to improve machining efficiency through reduced tool wear. The investigation enables the environmentally clean rough machining of Ti–6Al–4V. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
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