Advances in Materials Science and Engineering The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Effect of the Change of Deposition Time on the Secondary Direction and Abnormal Shape of Grains Growth of SnO2 Thin Films Tue, 04 Aug 2015 13:43:22 +0000 SnO2 thin films were grown on Si substrate using the low pressure chemical vapor deposition method. Observations made through electron microscopy indicate that thin films tend to grow with a constant direction when deposited at a temperature of 420°C for 5, 10, 20, or 30 min. However, when the deposition time increases, the particles forming the thin films are subject to a secondary growth. Observations made under a high-resolution transmission electron microscope reveal the lattice shape characteristic of thin films, with an overlapped or wrinkled flower form, and indicate that thin films growth takes place in different directions during the secondary growth. Measurements of the Hall effect show that the carriers mobility in the thin films increases linearly with the deposition time, whereas the carrier density decreases. The Hall Rh value increased linearly until 20 min deposition time, whereas for thin film grown for 30 min it decreased rapidly, showing a relatively similar behaviour to the carrier density. This is because as the deposition time becomes longer, the second growth and atypical shape occurs, leading to an increase of the thin films Rh value. This phenomenon indicates that the deposition time of thin films affects their carrier density and atypical overlapped or wrinkled flower form. Jin Jeong Copyright © 2015 Jin Jeong. All rights reserved. Trend and Development of Semisolid Metal Joining Processing Tue, 04 Aug 2015 12:00:47 +0000 The semisolid metal joining (SSMJ) process or thixojoining process has recently been developed based on the principles of SSM processing, which is a technology that involves the formation of metal alloys between solidus and liquidus temperatures. Thixojoining has many potential benefits, which has encouraged researchers to carry out feasibility studies on various materials that could be utilized in this process and which could transform the production of metal components. This paper reviews the findings in the literature to date in this evolving field, specifically, the experimental details, technology considerations for industrialization, and advantages and disadvantages of the various types of SSMJ methods that have been proposed. It also presents details of the range of materials that have been joined by using the SSMJ process. Furthermore, it highlights the huge potential of this process and future directions for further research. M. N. Mohammed, M. Z. Omar, Z. Sajuri, M. S. Salleh, and K. S. Alhawari Copyright © 2015 M. N. Mohammed et al. All rights reserved. Numerical Study on Crack Propagation by Using Softening Model under Blasting Sun, 02 Aug 2015 16:05:24 +0000 A mixed failure criterion, which combined the modified maximum principal stress criterion with the damage model of tensile crack softening, was developed to simulate crack propagation of rock under blasting loads. In order to validate the proposed model, a set of blasting models with a crack and a borehole with different incident angles with the crack were established. By using this model, the property of crack propagation was investigated. The linear equation of state (EOS) was used for rock, and the JWL EOS was applied to the explosive. In order to validate the numerical simulation results, experiments by using PMMA (polymethyl methacrylate) with a crack and a borehole were carried out. The charge structure and incident angle of the blasting experimental model were the same as those in the numerical models. The experiment results agree with the numerical simulation results. Rong Hu, Zheming Zhu, Jun Xie, and Dingjun Xiao Copyright © 2015 Rong Hu et al. All rights reserved. Effects of Nano-TiO2 on the Toughness and Durability of Cement-Based Material Thu, 30 Jul 2015 08:43:29 +0000 The effects of nano-TiO2 (NT) on microstructures and mechanical properties of cement mortars were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). Results show that 3% NT can remarkably increase the tensile/flexural strengths (i.e., the toughness is improved) and promote the precipitation of AFt crystal. The flexural and tensile strengths have significant positive correlation to the formation amount of AFt. The pores of mortars can be significantly refined and shift to harmless pores by controlling the growth of CH crystal and increasing the hydration reaction rate. The durability of cement-based materials is discussed by testing their water absorption and water-vapour permeability. Results show that the addition of 3% NT can decrease the water absorption ratio by 40–65%, water absorption coefficients by more than 40%, and water-vapour permeability coefficients by 43.9%, indicating that 3% NT can effectively improve the compactness and durability of cement-based materials. Baoguo Ma, Hainan Li, Junpeng Mei, Xiangguo Li, and Fangjie Chen Copyright © 2015 Baoguo Ma et al. All rights reserved. Preparation, Characterization, and Photocatalytic Properties of Modified Red Mud Wed, 29 Jul 2015 08:38:22 +0000 Solid waste red mud was modified by HCl leaching. The structure property and composition of modified red mud were investigated by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET). Under UV irradiation, methyl orange (MO) aqueous solution was photodegraded by modified red mud. The obtained results showed that the specific surface area of modified red mud was 317.14 m2/g, which was about 40 times higher than that of the normal red mud. After UV irradiation for 50 min, the removal percentage of MO reached 94.2%. The study provided a novel way for the application of red mud to the photocatalytic degradation of organic wastes. Mingjie Ma, Guanyu Wang, Zhengpeng Yang, Shanxiu Huang, Weijie Guo, and Yuxia Shen Copyright © 2015 Mingjie Ma et al. All rights reserved. Application of Biomaterials and Inkjet Printing to Develop Bacterial Culture System Tue, 28 Jul 2015 11:45:40 +0000 We created an automated bioassay system based on inkjet printing. Compared to conventional manual bacterial culture systems our printing approach improves the quality as well as the processing speed. A hydrophobic/hydrophilic pattern as a container supporting a culture medium was built on filter paper using a toluene solution of polystyrene for hydrophobization, followed by toluene printing to create several hydrophilic areas. As culture media we used a novel poly(vinyl alcohol) based hydrogel and a standard calcium alginate hydrogel. The poly(vinyl alcohol) hydrogel was formed by physical crosslinking poly(vinyl alcohol) with adipic acid dihydrazide solutions. The conditions of poly(vinyl alcohol) gelation were optimized for inkjet printability and the optimum mixture ratio was determined. The calcium alginate hydrogel was formed by chemical reaction between sodium alginate and CaCl2 solutions. Together with nutrients both hydrogel solutions were successfully printed on paper by means of the modified inkjet printer. The amount of each solution was demanded simply by outputting CMYK values. In the last step bacterial cells were printed on both hydrogel media. For both media we achieved a stable bacteria growth which was confirmed by microscopical imaging of the developed bacterial colonies. Tithimanan Srimongkon, Shusaku Mandai, and Toshiharu Enomae Copyright © 2015 Tithimanan Srimongkon et al. All rights reserved. Physical and Thermal Characterization of Alkali Treated Rice Husk Reinforced Polypropylene Composites Mon, 27 Jul 2015 13:27:17 +0000 Rice husk (RH) reinforced polypropylene- (PP-) based composites were prepared by compression molding. The RH was treated with sodium hydroxide solution (1 wt%); then composites were prepared using varying percentages of RH (5 to 20 wt%). The thermomechanical, spectroscopic, and morphological properties of the prepared composites (RH-PP) were investigated. The scanning electron microscopic (SEM) analysis showed better interfacial adhesion between alkali treated RH and the matrix PP. The Fourier Transform Infrared (FTIR) spectra confirmed the chemical bonding.The results revealed that physical properties as well as thermal stability of the composites improved significantly with the addition of alkali treated RH in PP matrix. Ismat Zerin Luna, Krishna Chandra Dam, A. M. Sarwaruddin Chowdhury, Md. Abdul Gafur, Nuruzzaman Khan, and Ruhul A. Khan Copyright © 2015 Ismat Zerin Luna et al. All rights reserved. Asphalt Mixture for the First Asphalt Concrete Directly Fastened Track in Korea Mon, 27 Jul 2015 09:02:03 +0000 The research has been initiated to develop the asphalt mixtures which are suitable for the surface of asphalt concrete directly fastened track (ADFT) system and evaluate the performance of the asphalt mixture. Three aggregate gradations which are upper (finer), medium, and below (coarser). The nominal maximum aggregate size of asphalt mixture was 10 mm. Asphalt mixture design was conducted at 3 percent air voids using Marshall mix design method. To make impermeable asphalt mixture surface, the laboratory permeability test was conducted for asphalt mixtures of three different aggregate gradations using asphalt mixture permeability tester. Moisture susceptibility test was conducted based on AASHTO T 283. The stripping percentage of asphalt mixtures was measured using a digital camera and analyzed based on image analysis techniques. Based on the limited research results, the finer aggregate gradation is the most suitable for asphalt mixture for ADFT system with the high TSR value and the low stripping percentage and permeable coefficient. Flow number and beam fatigue tests for finer aggregate asphalt mixture were conducted to characterize the performance of asphalt mixtures containing two modified asphalt binders: STE-10 which is styrene-butadiene-styrene (SBS) polymer and ARMA which is Crum rubber modified asphalt. The performance tests indicate that the STE-10 shows the higher rutting life and fatigue life. Seong-Hyeok Lee, Dae-Wook Park, Hai Viet Vo, and Samer Dessouky Copyright © 2015 Seong-Hyeok Lee et al. All rights reserved. The Characteristics of CNT/Cement Composites with Acid-Treated MWCNTs Mon, 27 Jul 2015 06:17:15 +0000 This study investigated the effects of acid-treated MWCNTs on the workability, compressive and tensile strength, porosity, and microstructure of CNT/cement composites. While workability decreased with acid treatment of CNTs, compressive and tensile strength improved significantly. Strength was also enhanced by using acid-treated CNTs alone, compared to using a surfactant with acid-treated CNTs. MIP analysis revealed that the porosity decreases from using acid-treated CNTs and that using acid-treated CNTs without a surfactant was more effective in reducing the size of micropores. A SEM analysis revealed improved CNT dispersion and dense hydration products in cement composites containing acid-treated CNTs. Ultimately, the use of acid-treated CNTs improved the CNT dispersion within CNT/cement composites, enhanced the pore structure, and formed denser hydration products around CNTs. Su-Tae Kang, Jun-Yeong Seo, and Sun-Hong Park Copyright © 2015 Su-Tae Kang et al. All rights reserved. Assessing the Hardness of Quenched Medium Steel Using an Ultrasonic Nondestructive Method Sun, 26 Jul 2015 09:36:07 +0000 Developing new materials or improving their heat treatment techniques is key to industrial upgrades for increasing fastener product quality. Nowadays, high tensile strength bolts are heat-treated to achieve desired mechanical properties such as hardness, strength, toughness, and resistance to fatigue and wear. Ultrasound detection is one widely used nondestructive inspection technique. Based on the characteristics of wave transmission, the refraction, diffraction, and scattering of ultrasound wave velocity and attenuation in a material are governed by its grain boundary characteristics. In this study, C1045 middle carbon steel was heat-treated at various temperatures and then water-quenched, and the relationships among grain size, ultrasonic velocity, attenuation, and material hardness were then determined using two ultrasound sources. Our experimental results show that a smaller average grain size as well as higher hardness can be obtained from higher quenching temperatures. Faster acoustic velocities and slower attenuation coefficients are caused by higher material hardness. A scattering effect is more obvious for higher transducer frequencies. Our results demonstrate another nondestructive test that can assess the quenching process in the fastener industry. Shao-Yi Hsia and Yu-Tuan Chou Copyright © 2015 Shao-Yi Hsia and Yu-Tuan Chou. All rights reserved. A Thermo-Hygro-Coupled Model for Chloride Penetration in Concrete Structures Wed, 22 Jul 2015 13:42:46 +0000 Corrosion damage due to chloride attack is one of the most concerning issues for long term durability of reinforced concrete structures. By developing the reliable mathematical model of chloride penetration into concrete structures, it can help structural engineers and management agencies with predicting the service life of reinforced concrete structures in order to effectively schedule the maintenance, repair, and rehabilitation program. This paper presents a theoretical and computational model for chloride diffusion in concrete structures. The governing equations are taking into account the coupled transport process of chloride ions, moisture, and temperature. This represents the actual condition of concrete structures which are always found in nonsaturated and nonisothermal conditions. The fully coupled effects among chloride, moisture, and heat diffusion are considered and included in the model. The coupling parameters evaluated based on the available material models and test data are proposed and explicitly incorporated in the governing equations. The numerical analysis of coupled transport equations is performed using the finite element method. The model is validated by comparing the numerical results against the available experimental data and a good agreement is observed. Nattapong Damrongwiriyanupap, Suchart Limkatanyu, and Yunping Xi Copyright © 2015 Nattapong Damrongwiriyanupap et al. All rights reserved. Fullerenol-Capped Porous Silica Nanoparticles for pH-Responsive Drug Delivery Tue, 21 Jul 2015 14:07:28 +0000 Novel nanocomposite containing fullerenol nanoparticles (FNP) and porous silica nanoparticles (PSNs) was constructed and characterized. The capability of FNP to serve as a pore-capping agent and for entrapping 9-aminoacridine (9-AA) inside the pores of the PSN material was also demonstrated. Nitrogen sorption measurements evidence the successful capping of the silica pores while thermogravimetric analysis of FNP loaded PSN indicates the existence of pore-loaded fullerenol molecules. Higher amount of the drug release was noted by exposing the material to weakly acidic conditions in comparison to physiological pH, which may find application in targeted treatment of weakly acidic tumor tissues. Nikola Ž. Knežević, Sanja Milenković, Danica Jović, Slavica Lazarevic, Jasminka Mrdjanović, and Aleksandar Djordjevic Copyright © 2015 Nikola Ž. Knežević et al. All rights reserved. Mechanical Properties and Nondestructive Testing of Advanced Materials 2014 Tue, 21 Jul 2015 11:17:21 +0000 Yan Yang, Xing Chen, Youngsoo Choi, and Boseon Kang Copyright © 2015 Yan Yang et al. All rights reserved. Design, Synthesis, and Characterization of Hybrid Materials Tue, 21 Jul 2015 11:14:55 +0000 Young-Keun Jeong, Mihai Barboiu, Simo-Pekka Hannula, and Kwang Ho Kim Copyright © 2015 Young-Keun Jeong et al. All rights reserved. The Polymerization of MMA and ST to Prepare Material with Gradient Refractive Index in Electric Field Thu, 16 Jul 2015 11:17:51 +0000 Light scattering material with gradient refractive index was prepared under the electrical field by taking methyl methacrylate (MMA) monomer as the matrix with the addition of a little preheated styrene (ST) and peroxidation benzoin formyl (BPO). The material obtained under electrical field presented different transmittance and molecular weight at different parts of the cylindrical sample along the axis of the direction of electric field which led to the layering phenomenon and gradient refractive index. The disparity of molecular weight between different layers can be as much as 230 thousand. There were several peaks in the figure of GPC test of the sample under electric field. This proved that there were polymers with different molecular weights in the sample. Therefore, it can be concluded that electrical field has a significant effect on polymerization. Yao Huang, Daming Wu, Dongyun Ren, Qingyun Meng, and Xiaojun Di Copyright © 2015 Yao Huang et al. All rights reserved. Optimization and Static Stress Analysis of Hybrid Fiber Reinforced Composite Leaf Spring Thu, 16 Jul 2015 09:59:27 +0000 A monofiber reinforced composite leaf spring is proposed as an alternative to the typical steel one as it is characterized by high strength-to-weight ratio. Different reinforcing schemes are suggested to fabricate the leaf spring. The composite and the typical steel leaf springs are subjected to the same working conditions. A weight saving of about more than 60% can be achieved while maintaining the strength for the structures under consideration. The objective of the present study was to replace material for leaf spring. This study suggests various materials of hybrid fiber reinforced plastics (HFRP). Also the effects of shear moduli of the fibers, matrices, and the composites on the composites performance and responses are discussed. The results and behaviors of each are compared with each other and verified by comparison with analytical solution; a good convergence is found between them. The elastic properties of the hybrid composites are calculated using rules of mixtures and Halpin-Tsi equation through the software of MATLAB v-7. The problem is also analyzed by the technique of finite element analysis (FEA) through the software of ANSYS v-14. An element modeling was done for every leaf with eight-node 3D brick element (SOLID185 3D 8-Node Structural Solid). Luay Muhammed Ali Ismaeel Copyright © 2015 Luay Muhammed Ali Ismaeel. All rights reserved. Shear Capacity and Failure Behavior of Steel-Reinforced High Ductile Concrete Beams Thu, 16 Jul 2015 09:40:48 +0000 The shear behavior of six high ductile fiber reinforced concrete (HDC) beams is studied to investigate the influence of shear-span ratio and HDC mechanical property on the improvement of the shear failure mode and shear capacity of short beams. Four steel-reinforced high ductile concrete beams (SHDC) beams with different shear span ratios are tested under concentrated load at midspan. To study the effect of stirrups and steel on the shear capacity of short beams, two additional specimens without steel but one including stirrups are investigated. The main aspects of SHDC beams are discussed in detail, such as failure mode, deformability, and shear capacity. Test results show that the SHDC short beams keep high residual bearing capacity and great integrity when suffering from large deformation. It is revealed that HDC increased the shear ductility and improved the shear failure mode of short beams. A comparison with the shear equations of Chinese YB9082-2006 shows that the Chinese Code equation provides conservative estimation for HDC beams. This study proposes modifications to the equation for predicting the shear capacity of HDC beams. Mingke Deng, Jie Dai, Huasong Lu, and Xingwen Liang Copyright © 2015 Mingke Deng et al. All rights reserved. Conductivity and Dielectric Studies of Lithium Trifluoromethanesulfonate Doped Polyethylene Oxide-Graphene Oxide Blend Based Electrolytes Thu, 16 Jul 2015 09:18:06 +0000 Series of polymer blend consisting of polyethylene oxide (PEO) and graphene oxide (GO) as co-host polymer were prepared using solution cast method. The most amorphous PEO-GO blend was obtained using 90 wt.% of PEO and 10 wt.% of GO as recorded by X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FTIR) analysis proved the interaction between PEO, GO, lithium trifluoromethanesulfonate (LiCF3SO3), and ethylene sulfite (ES). Incorporation of 25 wt.% LiCF3SO3 into the PEO-GO blend increases the conductivity to  S cm−1. The conductivity starts to decrease when more than 25 wt.% salt is doped into the polymer blend. The addition of 1 wt.% ES into the polymer electrolyte has increased the conductivity to  S cm−1. Dielectric studies show that all the electrolytes obey non-Debye behavior. A. A. Azli, N. S. A. Manan, and M. F. Z. Kadir Copyright © 2015 A. A. Azli et al. All rights reserved. Influence of Tensile Speeds on the Failure Loads of the DP590 Spot Weld under Various Combined Loading Conditions Thu, 16 Jul 2015 07:54:05 +0000 This paper is concerned with the evaluation of the dynamic failure load of the spot weld under combined axial and shear loading conditions. The testing fixture is designed to impose the combined axial and shear load on the spot weld. Using the proposed testing fixtures and specimens, quasi-static and dynamic failure tests of the spot weld are conducted with seven different combined loading conditions. The failure load and failure behavior of the spot weld are investigated with different loading conditions. Effect of tensile speeds on the failure load of the spot weld, which is critical for structural crashworthiness, is also examined based on the experimental data. The failure loads measured from the experiment are decomposed into the two components along the axial and shear directions and failure contours are plotted with different loading speeds. Dynamic sensitivities of failure loads with various combined loading conditions were also analyzed. Experimental results indicate that the failure contour is expanded with increasing loading speeds and failure loads show similar dynamic sensitivity with respect to the loading angles. Jung Han Song and Hoon Huh Copyright © 2015 Jung Han Song and Hoon Huh. All rights reserved. Characteristics of Nanophase WC and WC-3 wt% (Ni, Co, and Fe) Alloys Using a Rapid Sintering Process for the Application of Friction Stir Processing Tools Thu, 16 Jul 2015 07:38:58 +0000 Microstructures and mechanical characteristics of tungsten carbide- (WC-) based alloys, that is, WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe, fabricated using a spark plasma sintering (SPS) method for the application of friction stir processing tools were evaluated. The sintered bodies with a diameter of 66 mm showed relative densities of up to 99% with an average particle size of 0.26~0.41 μm under a pressure condition of 60 MPa with an electric current for 35 min without noticeable grain growth during sintering. Even though no phase changes were observed after the ball milling process the phases of W2C and appeared in all sintered samples after sintering. The Vickers hardness and fracture toughness of the WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe samples ranged from 2,240 kg mm2 to 2,730 kg mm2 and from 6.3 MPa·m1/2 to 9.1 MPa·m1/2, respectively. Daeup Kim, Young Choi, Yongil Kim, and Seungboo Jung Copyright © 2015 Daeup Kim et al. All rights reserved. Preparation and Properties of OMMT/PU Composites Thu, 16 Jul 2015 06:53:21 +0000 Prepolymer of polyurethane (PU) was prepared by toluene diisocyanate (TDI) and polyether diol through polymerization, organically modified montmorillonite (OMMT) gained by montmorillonite (MMT) that was modified by octadecyl trimethyl ammonium chloride (OTAC), and the OMMT was used as intercalator; alcohol-based OMMT/PU adhesive was synthesized. The micromorphology of OMMT/PU adhesives was observed by XRD, SEM, and AFM, and the shear strength, elongation at break, peel strength, and water resistance were tested and the relationship between structure and properties of the adhesives was observed and analyzed. XRD suggested that OMMT has been completely peeled in the polyurethane matrix and the spacing of layers has increased. SEM and AFM indicated that the OMMT dispersed evenly in the PU matrix and had a good transition with PU matrix, and the interface effects between two phases were strong. The results of the mechanical properties showed that OMMT could significantly help to improve properties of OMMT/PU adhesive, and the shearing strength, fracture tensile strength, and peel strength of 4 wt% OMMT/PU adhesive were 7.24 MPa, 2.14 MPa, and 451.2 N/m, respectively; the water absorption quantity was 2.82%. Compared with the unmodified PU, the shearing strength, tensile strength, and elongation at break of 4 wt% OMMT/PU adhesive were increased by 36.75%, 134.90%, and 76.80%, respectively. The peel strength decreased by 30.76%, and the water absorption decreased by 17.54%, in the meanwhile. Chen Yufei, Han Yang, Dai Qiwang, Zhang Xiwang, and Qingyu Zhang Copyright © 2015 Chen Yufei et al. All rights reserved. Fabrication of a Microtubular La0.6Sr0.4Ti0.2Fe0.8O3−δ Membrane by Electrophoretic Deposition for Hydrogen Production Thu, 16 Jul 2015 06:53:05 +0000 Microtubular type La0.6Sr0.4Ti0.2Fe0.8O3−δ (LSTF) membranes were prepared by electrophoretic deposition (EPD). The oxygen permeation and hydrogen production behavior of the membranes were investigated under various conditions. LSTF green layer was successfully coated onto a carbon rod and, after heat treatment at 1400°C in air, a dense LSTF tubular membrane with a thickness of 250 mm can be obtained. The oxygen permeation and hydrogen production rate were enhanced by CH4 in the permeate side, and the hydrogen production rate by water splitting was 0.22 mL/min·cm2 at 1000°C. It is believed that hydrogen production via water splitting using these tubular LSTF membranes is possible. Kyoung-Jin Lee, Yeong-Ju Choe, Jun-Sung Lee, and Hae-Jin Hwang Copyright © 2015 Kyoung-Jin Lee et al. All rights reserved. Kinetic Studies of Atom Transfer Radical Polymerisations of Styrene and Chloromethylstyrene with Poly(3-hexyl thiophene) Macroinitiator Thu, 16 Jul 2015 06:38:26 +0000 Poly(3-hexyl thiophene)-b-poly(styrene-co-chloromethylstyrene) copolymers, to be used as a prepolymer for preparing donor-acceptor block copolymers for organic solar cells, have been synthesised by reacting P3HT macroinitiators with styrene and chloromethylstyrene via three types of atom transfer radical polymerisation (ATRP) systems, which are (1) a normal ATRP, (2) activators generated by electron transfer (AGET), and (3) a simultaneous reverse and normal initiation (SR&NI). The kinetics of these ATRP systems were studied as a function of monomers to the macroinitiator molar ratio. It was found that all of the three types of ATRP systems led to first order kinetics with respect to monomers. The highest rate constant (k) of 3.4 × 10−3 s−1 was obtained from the SR&NI ATRP system. The molecular weights of the product determined by the GPC were lower than were the theoretical values. The result was discussed in light of the chain transfer reaction to the poly(chloromethylstyrene) repeating units. Morphology of the synthesized block copolymers, examined by an atomic force microscopy (AFM), were also compared and discussed. Nattawoot Rattanathamwat, Jatuphorn Wootthikanokkhan, Nonsee Nimitsiriwat, Chanchana Thanachayanont, and Udom Asawapirom Copyright © 2015 Nattawoot Rattanathamwat et al. All rights reserved. Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating Thu, 16 Jul 2015 06:25:52 +0000 High-velocity oxygen-fuel (HVOF) thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C) thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. The graphite and excessively sprayed oxygen formed carbon oxide gases, and these gases formed porous coating by evolution of the gases. The surface properties were improved by HVOF coating and were improved further by CO2 laser heat treatment (LH). Wear resistance of In718 surface was improved by coating and LH at 25°C and an elevated temperature of 450°C, resulting in reduction of wear trace traces, and was further improved by LH of the coating in reducing wear depth. Corrosion resistance due to coating in sea water was improved by LH. HVOF coating of WC-metal powder on a metal surface and a LH of the coating were highly recommended for the improvement of In718 surface properties, the friction behavior, and wear resistance. Hui Gon Chun, Tong Yul Cho, Jae Hong Yoon, and Gun Hwan Lee Copyright © 2015 Hui Gon Chun et al. All rights reserved. Feasibility Studies on Underwater Laser Surface Hardening Process Thu, 16 Jul 2015 06:24:29 +0000 Laser surface hardening process is a very promising hardening method for ferrous and nonferrous alloys where transformations occur during cooling after laser melting in the solid state. This study experimentally characterizes laser surface hardening of tool steel in both water and air. For the underwater operation, laser surface scanning is performed over the tool steel surface which is immersed in water. The laser surface hardening tests are performed with a maximum 200 W fiber laser with a Gaussian distribution of energy in the beam. For the surface hardening, single-track melting experiment which sequentially scans elongated path of single line has been performed. As the hardened depth depends on the thermal conductivity of the material, the surface temperature and the penetration depth may be varied by underwater laser processing. The feasibility of underwater laser surface hardening process is discussed on the basis of average hardness level and hardened bead shape. Biao Jin, Min Li, TaeWoo Hwang, and YoungHoon Moon Copyright © 2015 Biao Jin et al. All rights reserved. Microwave-Promoted Synthesis of Sulfonated Metallophthalocyanines and Aggregation in Different Solvents Wed, 15 Jul 2015 09:12:48 +0000 Five metallosulfophthalocyanines (Fe, Ni, Zn, Co, and Cu) compounds were synthesized by microwave irradiation. Compared to the conventional method of synthesis in terms of reaction time and yields, the microwave-promoted synthesis is preferred with high product yield and short reaction time. All synthesized products were characterized with MALDI-TOF mass spectrum, Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), and X-ray diffraction (XRD). Aggregation behavior of the five metallosulfophthalocyanines (MSPc) in different solvents was studied by UV-Vis spectroscopy separately in N,N-dimethyl formamide (DMF) and NaOH aqueous solution (5%wt). A redshift of maximum absorption wavelength and deviations from Lambert-Beer law with increasing the concentration were observed. The dimerization equilibrium constants (K) of the five MSPc were determined, respectively. Zhenhua Cheng, Na Cui, Shengjuan Jiang, Hongxiao Zhang, Lijun Zhu, and Daohong Xia Copyright © 2015 Zhenhua Cheng et al. All rights reserved. Experimental Study on Steel to FRP Bonded Lap Joints in Marine Applications Tue, 14 Jul 2015 09:34:08 +0000 Steel structures coated with fiber-reinforced polymer (FRP) composites have gained wide acceptance in marine industry due to their high strength-to-weight ratio, good protection from environmental degradation, and impact loads. In this study, adhesive bonding performance of single-lap bonded joints composed of steel coated with FRP has been investigated experimentally for three different surface roughness and two epoxy types. Single-lap bonded joints have been tested under tensile loading. The adhesive bonding performance has been evaluated by calculating the strain energy values. The results reveal that the surface roughness of steel has a significant effect on the bonding performance of steel to FRP combinations and the performance of the resin can be improved by using the primer in an economical way. Çiçek Özes and Nurhan Neşer Copyright © 2015 Çiçek Özes and Nurhan Neşer. All rights reserved. Effect of Reinforcement on Early-Age Concrete Temperature Stress: Preliminary Experimental Investigation and Analytical Simulation Tue, 14 Jul 2015 06:23:59 +0000 For concrete under short-term loading, effect of reinforcement on concrete crack resistance capability is usually negligible; however, recent research results show that extension of this viewpoint to concrete under long-term loading (temperature variation) may be unsuitable. In order to investigate this phenomenon, this paper presents the experimental and analytical results of early-age reinforced concrete temperature stress development under uniaxial restraint. The experiments were carried out on a temperature stress testing machine (TSTM). Experimental results show that the coupling of reinforcement and concrete creep behavior influenced the concrete temperature stress development, and nearly 16% of concrete stress was reduced in the current research. Moreover, the cracking time of reinforced concrete was also delayed. Finally, based on the principle of superposition, analytical simulations of effect of reinforcement on concrete temperature stress have been performed. Jianda Xin, Siqing Lin, Nannan Shi, Jianshu Ouyang, and Dahai Huang Copyright © 2015 Jianda Xin et al. All rights reserved. Effect of Heartwood and Sapwood Ratio on Adhesion Strength of Finished Wood Species Sun, 12 Jul 2015 11:22:34 +0000 The objective of this study was to determine adhesion strength of samples from wood species coated with cellulose varnish as function of heartwood and sapwood ratio. Roughness of the specimens from four different species was measured employing stylus type equipment before they were coated with varnish. Pull-off testing unit was employed to determine adhesion strength of the samples. Based on the findings in this work it seems that no significant difference was determined between adhesion strength values of the samples prepared from heartwood and sapwood portions. The highest adhesion strength value of 2.62 N/mm2 was found for the beech samples sanded with 80-grit sand paper. Overall rougher surfaces of the samples resulted in higher adhesion strength between finish and substrate. Turgay Ozdemir, Salim Hiziroglu, and Mutlu Kocapınar Copyright © 2015 Turgay Ozdemir et al. All rights reserved. Hot Embossing of Zr-Based Bulk Metallic Glass Micropart Using Stacked Silicon Dies Thu, 09 Jul 2015 10:51:05 +0000 We demonstrated hot embossing of Zr65Cu17.5Ni10Al7.5 bulk metallic glass micropart using stacked silicon dies. Finite element simulation was carried out, suggesting that it could reduce the stress below 400 MPa in the silicon dies and enhance the durability of the brittle silicon dies when using varying load mode (100 N for 60 s and then 400 N for 60 s) compared with using constant load mode (200 N for 120 s). A micropart with good appearance was fabricated under the varying load, and no silicon die failure was observed, in agreement with the simulation. The amorphous state of the micropart was confirmed by differential scanning calorimeter and X-ray diffraction, and the nanohardness and Young’s modulus were validated close to those of the as-cast BMG rods by nanoindentation tests. The results proved that it was feasible to adopt the varying load mode to fabricate three-dimensional Zr-based bulk metallic glass microparts by hot embossing process. Zhijing Zhu, Chuanyun Yi, Tielin Shi, Yichun Zhang, Yang Gao, and Guanglan Liao Copyright © 2015 Zhijing Zhu et al. All rights reserved.