The production of metal matrix composites with elevated mechanical properties depends largely on the reinforcing phase properties. Due to the poor oxidation resistance of multiwalled carbon nanotubes (MWCNTs) as well as their high reactivity with molten metal, the processing conditions for the production of MWCNT-reinforced metal matrix composites may be an obstacle to their successful use as reinforcement. Coating MWCNTs with a ceramic material that acts as a thermal protection would be an alternative to improve oxidation stability. In this work, MWCNTs previously functionalized were coated with titanium dioxide (TiO2) layers of different thicknesses, producing a core-shell structure. Heat treatments at three different temperatures (500&#xb0;C, 750&#xb0;C, and 1000&#xb0;C) were performed on coated nanotubes in order to form a stable metal oxide structure. The MWCNT/TiO2 hybrids produced were evaluated in terms of thermal stability. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS), and X-ray photoelectron spectroscopy (XPS) were performed in order to investigate TiO2-coated MWCNT structure and thermal stability under oxidative atmosphere. It was found that the thermal stability of the TiO2-coated MWCNTs was dependent of the TiO2 layer morphology that in turn depends on the heat treatment temperature.

Laura Ang&#xe9;lica Ardila Rodriguez

Dilermando Nagle Travessa

Core/Shell Structure of TiO2-Coated MWCNTs for Thermal Protection for High-Temperature Processing of Metal Matrix Composites

Alkali-activated matrices are suitable materials for the immobilization of hazardous materials such as heavy metals. This paper is focused on the comparison of immobilization characteristics of various inorganic composite materials based on blast furnace slag and on the influence of various dosages of the heavy metal Pb on the mechanical properties and fixation ability of prepared matrices. Blast furnace slag (BFS), fly ash, and standard sand were used as raw materials, and sodium water glass was used as an alkaline activator. Pb(NO3)2 served as a source of heavy metal and was added in various dosages in solid state or as aqueous solution. The immobilization characteristics were determined by leaching tests, and the content of Pb in the eluate was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The microstructure of matrices and distribution of Pb within the matrix were determined by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Increasing the dosage of the heavy metal had negative impacts on the mechanical properties of prepared matrices. The leaching tests confirmed the ability of alkali-activated materials to immobilize heavy metals. With increasing addition of Pb, its content in eluates increased.

Jan Kopl&#xed;k

Jarom&#xed;r Po&#x159;&#xed;zka

Luk&#xe1;&#x161; Kalina

Ji&#x159;&#xed; M&#xe1;silko

Mat&#x11b;j B&#x159;ezina

Influence of Pb Dosage on Immobilization Characteristics of Different Types of Alkali-Activated Mixtures and Mortars

This study uses the submerged arc discharge method (SADM) and the concentrated energy of arc to melt silver metal in deionized water (DW) so as to prepare metal fluid with nanoparticles and submicron particles. The process is free from any chemical agent; it is rapid and simple, and rapid and mass production is available (0.5&#x2009;L/min). Aside from the silver nanoparticle (Ag0), silver ions (Ag&#x2b;) exist in the colloidal Ag prepared by the system. In the preparation of colloidal Ag, polyvinyl alcohol (PVA) is used as an additive so that the Ag0/Ag&#x2b; concentration, arcing rate, peak, and scanning electron microscopic (SEM) images in the cases with and without PVA can be analyzed. The findings show that the Ag0/Ag&#x2b; concentration increases with the addition level of PVA, while the nano-Ag and Ag&#x2b; electrode arcing rate rises. The UV-Vis absorption peak increases Ag0 absorbance and shifts as the dispersity increases with PVA addition. Lastly, with PVA addition, the proposed method can prepare smaller and more amounts of Ag0 nanoparticles, distributed uniformly. PVA possesses many distinct features such as cladding, dispersion, and stability.

Kuo-Hsiung Tseng

Chih-Ju Chou

To-Cheng Liu

Der-Chi Tien

Tong-chi Wu

Leszek Stobinski

Interactive Relationship between Silver Ions and Silver Nanoparticles with PVA Prepared by the Submerged Arc Discharge Method

This article investigated the microstructure and damping property of TPU composites with different contents of ultraviolet absorbents. It can be found that the ultraviolet absorbents formed fiber-shaped precipitations in the TPU matrix. The UV-328 was randomly distributed in the matrix and exhibited a weak interfacial bonding with the matrix. In comparison, the UV-329 was well embedded in the matrix and formed a relatively better interfacial bonding and compatibility with the TPU matrix. The damping factor tan&#x3b4; of both 328-composites and 329-composites had been reduced gradually with increasing content of ultraviolet absorbents at the glass transition temperature range due to the fact that the ultraviolet absorbents were in the crystalline state which decreased the volume content of the viscoelastic TPU matrix. But the tan&#x3b4; increased at the temperature range of higher than the glass transition temperature, which should be related to the dominance of interfacial frictions between the ultraviolet absorbents and the matrix on the energy absorption.

Jiang Chang

Bing Tian

Li Li

Yufeng Zheng

Microstructure and Damping Property of Polyurethane Composites Hybridized with Ultraviolet Absorbents

The geometric modeling and finite element modeling of the whole structure of an electrostatic precipitator and its main components consisting of top beam, column, bottom beam, and bracket were finished. The strength calculation was completed. As a result, the design of the whole structure of the electrostatic precipitator and the main components were reasonable, the structure was in a balance state, its working condition was safe and reliable, its stress variation was even, and the stress distribution was regular. The maximum von Mises stress of the whole structure is 20.14&#x2009;MPa. The safety factor was large, resulting in a waste of material. An optimization mathematical model is established. Using the ANSYS first-order method, the dimension parameters of the main frame structure of the electrostatic precipitator were optimized. After optimization, more reasonable structural design parameters were obtained. The model weight is 72,344.11&#x2009;kg, the optimal weight is 49,239.35&#x2009;kg, and the revised weight is 53,645.68&#x2009;kg. Compared with the model weight, the optimal weight decreased by 23,104.76&#x2009;kg and the objective function decreased by 31.94&#x0025;, while the revised weight decreased by 18,698.43&#x2009;kg and the objective function decreased by 25.84&#x0025;.

Xuewen Wang

Bo Li

Zhaojian Yang

Finite Element Analysis and Lightweight Optimization Design on Main Frame Structure of Large Electrostatic Precipitator

Over the last decade increase in capacity and the intensity of vehicular traffic has increased manifoldly, including heavy trucks, super singles, and higher tire pressures, resulting in significant increase of dynamic loads on the road surface which in turn lead to high quality requirements for bitumen in order to avoid premature wear and failure of asphalt concrete pavements. One of the possibilities to increase the quality of bitumen is to use special additives and modifiers that can provide a high adhesion to mineral filler and inhibit the aging and degradation processes in the asphalt coating. To achieve this, in the present study composite modifiers based on bisimidazolines derivatives were synthesized. The developed polyfunctional modifier (PFM) of complex action provides enhanced thermal stability, significantly improves the adhesion between bitumen binder and aggregates, and also improves the physical-mechanical properties of the asphalt concrete. Based on the test results it is recommended to use the synthesized samples of the PFM additive with complex action in asphalt mixtures for road paving.

Alim Feizrakhmanovich Kemalov

Ruslan Alimovich Kemalov

Ilmira Maratovna Abdrafikova

Pavel Sagitovich Fakhretdinov

Dinar Zinnurovich Valiev

Polyfunctional Modifiers for Bitumen and Bituminous Materials with High Performance

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Advances in Materials Science and Engineering publishes research in all areas of materials science and engineering, including the synthesis and properties of materials, and their applications in engineering applications.

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Chief Editor, Amit Bandyopadhyay, is based at Washington State University and is interested in &nbsp;the fields of additive manufacturing or 3D printing of advanced materials. His current research is focused on metal additive manufacturing, biomedical devices and multi‑materials structures.

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Advances in Materials Science and Engineering - Table of contents 2018

Advances in Materials Science and Engineering | Hindawi

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Advances in Materials Science and Engineering publishes research in all areas of materials science and engineering, including the synthesis and properties of materials, and their applications in engineering applications.

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Advances in Materials Science and Engineering

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Advances in Materials Science and Engineering