Indian Journal of Materials Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Wear and Corrosion of Cast Al Alloy Piston with and without Brake Oil Sun, 01 Nov 2015 07:23:02 +0000 The effects of wear and corrosion of cast AA6061 aluminium alloy were studied with and without brake fluid using a wear jig while the corrosion rate was determined in brake fluid for 70 days under two experimental set-ups. The tests, yielded 0.00000123 g/mm2/min highest wear rate at 147000 wear cycles and 0.0334 mg/mm2/yr as the highest corrosion rate within the early 39th day of immersion in oil, the values being considered comparatively lower than those obtained for Al alloy in most common wet abrasion test and corrosion in aqueous solutions as previously reported in literature. The material loss rates to wear and corrosion were determined from the equations relating to wear and corrosion based on the ASTM designations. The results show that the combined actions of wear and corrosion contribute to the total loss of piston material immersed in brake oil. This is greater than either of their effects individually on cast Al alloy in the brake oil. Olawale Olarewaju Ajibola and Daniel Toyin Oloruntoba Copyright © 2015 Olawale Olarewaju Ajibola and Daniel Toyin Oloruntoba. All rights reserved. Effect of MgFeSi Inoculant on Properties of Cast 6061 Al Alloy for Brake Master Piston Application Sun, 18 Oct 2015 13:12:56 +0000 The influence of varying amount of MgFeSi inoculant on properties of cast 6061 Al alloy for brake master piston application has been studied and reported in this paper. Cast samples were produced at three pouring temperatures (700, 750, and 800°C) with MgFeSi varied from 1 to 3%. Wear resistance tests were performed on cast alloy in brake oil. Wear resistance tests results were validated by nondestructive examinations using photomicroscopy, SEM, EDX, and XRD data. The addition of MgFeSi influenced both the mechanical (hardness, strength, and wear resistance) and metallurgical properties (microstructures) of the cast alloy. Al grains were more refined and yielded good strength properties. Inoculating the melt with MgFeSi forms insoluble compound particles and is responsible for grain refinement. The increased amount of MgFeSi from 1 to 3% improved the wear resistance of the cast piston under lubricating condition using brake oil. Olawale Olarewaju Ajibola and Daniel Toyin Oloruntoba Copyright © 2015 Olawale Olarewaju Ajibola and Daniel Toyin Oloruntoba. All rights reserved. Synthesis, Characterization, and Investigation of Visible Light Photocatalytic Activity of C Doped TiO2/CdS Core-Shell Nanocomposite Mon, 05 Oct 2015 13:02:32 +0000 Carbon (C) doped TiO2/CdS core-shell nanocomposite (C/TiO2/CdS) was synthesized using microemulsion method. Synthesized powder was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and UV-visible spectrophotometery. TEM images reveal that C/TiO2/CdS core-shell heterostructure is successfully prepared with CdS as a core and C doped TiO2 as a shell. UV-visible absorption spectra show that CdS nanoparticles act as a sensitizer and effectively enhance the photoabsorption capacity of C/TiO2/CdS nanocomposite in visible region. Visible light photocatalytic activity of synthesized nanocomposite was evaluated for the degradation of methylene blue. C/TiO2/CdS core-shell nanocomposite exhibits better photocatalytic activity as compared to bare TiO2, CdS, CdS/TiO2, and C doped TiO2. Atul B. Lavand, Yuvraj S. Malghe, and Suraj H. Singh Copyright © 2015 Atul B. Lavand et al. All rights reserved. Thermoluminescence and Photoluminescence Study of Erbium Doped CaY2O4 Phosphor Wed, 30 Sep 2015 16:38:02 +0000 Phosphor doped with erbium ion with variable concentration (0.5–2 mol%) was synthesized by solid state reaction method. CaY2O4:Er3+ phosphor is characterized by X-ray diffraction technique for structural analysis and crystallite size calculation. Average crystallite size was found to be nearly 58 nm. Two prominent TL glow peaks found at 163°C associated with higher temperature peak 340°C. The peak intensity of higher temperature (340°C) peak was less as compared to lower temperature peak (163°C) because the deep trapping formation is less in case of UV irradiation. Sample shows good TL glow curve and for variable UV exposure time maximum TL intensity was found at 20 min UV exposure which is optimized UV exposure time. Sample was studied by photoluminescence emission spectra excited by xenon flash lamp with nearly 360 nm and four prominent peaks found at wavelengths 445, 525, 553, and 565 nm; here the 445 and 565 nm peak were intense as compared to others. From the PL emission spectra, it is concluded that the color tenability of prepared CaY2O4:Er3+ was blue-green and it is verified by CIE coordinate. Kinetic parameters of prepared phosphor were calculated by computerized glow curve deconvolution (CGCD) technique. Vikas Dubey, Ratnesh Tiwari, Raunak Kumar Tamrakar, Chandrabhushan Markande, Gajendra Singh Rathore, and Mahendra Kumar Pradhan Copyright © 2015 Vikas Dubey et al. All rights reserved. Influencing Parameters in the Photocatalytic Degradation of Organic Effluent via Nanometal Oxide Catalyst: A Review Thu, 17 Sep 2015 14:03:44 +0000 This paper aims to review the recent works on the photocatalytic degradation of organic pollutants in the presence of nanophotocatalyst. In this regard the effects of operation parameters which could influence the photocatalytic degradation of organic pollutants (such as catalyst preparation method, initial concentration of organic pollutants, presence of doping, catalyst loading, calcinations temperature, pH, presence of oxidants, UV intensity, temperature, and presence of supports) are discussed. Recent research suggests that the parameters mentioned above have great influence on the photocatalytic activity of prepared nanocatalyst. Also, the general mechanism of photocatalytic degradation and some recent synthesis methods are discussed here. A. Gnanaprakasam, V. M. Sivakumar, and M. Thirumarimurugan Copyright © 2015 A. Gnanaprakasam et al. All rights reserved. Mechanical Characterization and Machinability Behavior of Annealed AISI D6 Cold Working Steel Thu, 17 Sep 2015 06:59:47 +0000 Tool steels in metal forming industry are exposed to complex and aggressive conditions due to multiple effects (mechanical, thermal, or tribological loading) and require defined mechanical properties. Also machining of tool steel with poor machinability like AISI D6 to manufacture form tools is an extremely difficult task. This paper investigates the microstructural, mechanical, and machining behavior of AISI D6 steel in annealed and hardened conditions. Various mechanical tests indicated good hardenability, improved surface hardness, and phenomenal improvement in tensile strength but extremely poor resistance to impact in both annealed and hardened condition for this steel. The machining characteristics of AISI D6 steel were evaluated using a 2k unreplicated full factorial design approach and statistical techniques have been used to assess and identify the significant factors, namely, cutting speed, feed, depth of cut, and approach angle, in minimizing surface roughness and main cutting force while machining this steel with a carbide tool. It was found that the depth of cut, feed, and approach angle are the most significant factors affecting the surface roughness and depth of cut and feed affect the main cutting force. Cutting speed has no effect on surface roughness and main cutting force in machining of the steel in annealed condition. Manoj Nayak, Rakesh Sehgal, and Rajiv Kumar Sharma Copyright © 2015 Manoj Nayak et al. All rights reserved. Dynamics of Kaolinite-Urea Nanocomposites via Coupled DMSO-Hydroxyaluminum Oligomeric Intermediates Sun, 13 Sep 2015 13:10:56 +0000 Kaolinite-urea nanocomposites were prepared via intercalation reactions in an attempt to investigate the dynamic nature of kaolinite morphology for advanced applications in controlled release systems (CRS). Characterization was done using SEM-EDX, XRF, ATR-FTIR, XRD, and DT/DTG; Andreasen pipette sedimentation technique was used to determine the grain size distribution of the raw kaolinite. The X-ray diffraction pattern revealed the existence of an FCC Bravais lattice where the intercalation ratios attained were 51.2%, 32.4%, 7.0%, and 38.4% for hydroxyaluminum oligomeric intercalated kaolinite, substituted urea intercalated kaolinite, calcined DMSO intercalated kaolinite, and hydroxyaluminum reintercalated kaolinite, respectively, along with their respective crystallite sizes of 33.51–31.73 nm, 41.92–39.69 nm, 22.31–21.13 nm, and 41.86–39.63 nm. The outcomes demonstrated that the employed intercalation routes require improvements as the intercalation reactions were in average only ≈32.3%. The observations unveiled that it is possible to manipulate kaolinite structure into various morphologies including dense-tightly packed overlapping euhedral pseudo hexagonal platelets, stacked vermiform morphologies, postulated forms, and unique patterns exhibiting self-assembled curled glomeruli-like morphologies. Such a diversity of kaolinite morphologies expedites its advanced applications in the controlled release systems (CRS) such as drug delivery systems and controlled release fertilizers (CRFs). Siafu Ibahati Sempeho, Hee Taik Kim, Egid Mubofu, Alexander Pogrebnoi, Godlisten Shao, and Askwar Hilonga Copyright © 2015 Siafu Ibahati Sempeho et al. All rights reserved. Effect of Fly Ash and Carbon Reinforcement on Dry Sliding Wear Behaviour of Red Mud Thu, 27 Aug 2015 14:59:45 +0000 This paper explains the sliding wear performance of red mud, fly ash, and carbon composite coating on mild steel. The complex mixture of red mud, fly ash, and carbon is plasma sprayed at 9 kW operating power level. The coatings are examined to study the coating morphology, XRD phase transformation, wear rate, and wear morphology. Wear rate (in terms of cumulative mass loss) with sliding time has been demonstrated in the study. At first pure red mud is plasma coated to observe the coating characteristics and then compounded with 20% carbon, 30% carbon, and 20% carbon + 30% fly ash, separately by weight and sliding wear test conducted using pin on disc wear tester. The trial was performed at fixed track diameter of 100 mm and at sliding speed of 100 rpm (0.523 m/s) at a load of 30 N. The results are compared. Declined cumulative mass loss by inclusion of fly ash and carbon is seen. This might be due to augmented interfacial tension and dense film build-up at boundary layer. Harekrushna Sutar, Debashis Roy, and Subash Chandra Mishra Copyright © 2015 Harekrushna Sutar et al. All rights reserved. Evaluation of Chitosan Based Polymeric Matrices for Sustained Stomach Specific Delivery of Propranolol Hydrochloride Thu, 27 Aug 2015 08:43:21 +0000 The objective of the present investigation was to explore the potential of Chitosan based polymeric matrices as carrier for sustained stomach specific delivery of model drug Propranolol Hydrochloride. Briefly, single unit hydrodynamically balanced (HBS) capsule formulations were prepared by encapsulating in hard gelatin capsules, intimately mixed physical mixtures of drug, and cationic low molecular weight Chitosan (LMCH) in combination with either anionic medium viscosity sodium alginate (MSA) or sodium carboxymethylcellulose (CMCNa). The effect of incorporation of nonionic polymers, namely, tamarind seed gum (TSG) and microcrystalline cellulose (MCCP), was also investigated. It was observed that HBS formulations remained buoyant for up to 6 h in 0.1 M HCl, when LMCH : anionic/nonionic polymer ratio was at least 4 : 1. It was also observed that LMCH has formed polyelectrolyte complex (PEC) with MSA (4 : 1.5 ratio) and CMCNa (4 : 1 ratio) in situ during the gelation of HBS formulations in 0.1 M HCl. The retardation in drug release was attributed to the PEC formation between LMCH and MSA/CMCNa. Incorporation of MCCP (rapid gel formation) and TSG (Plug formation) was found to be innovative. From the data, it is suggested that Chitosan based polymeric matrices may constitute an excellent carrier for stomach specific drug delivery. Juhi Dubey, Anurag Verma, and Navneet Verma Copyright © 2015 Juhi Dubey et al. All rights reserved. Enhanced Catalytic Activity of Supported Gold Catalysts for Oxidation of Noxious Environmental Pollutant CO Thu, 27 Aug 2015 06:40:51 +0000 Noble metal nanomaterials have attracted mounting research attention for applications in diverse fields of catalysis, biology, and nanotechnology. In the present study, we have undertaken a detailed investigation on synthesis, characterization, and catalytic activity studies for CO oxidation by nanogold catalysts supported over CeO2 and CeO2-ZrO2 (1 : 1 mole ratio). The support systems were prepared by modified, simple precipitation technique and the Au supported samples were synthesized using deposition-precipitation with urea method. The physicochemical characterization was performed by XRD, ICP-AES, BET surface area, FT-IR, UV-Vis DRS, Raman Spectroscopy, TEM, and XPS techniques. Au/CeO2 catalyst showed more than 80% CO conversions at 30°C, whereas Au/CeO2-ZrO2 exhibited ~100% CO conversion at that temperature. The catalytic performance of Au catalysts is highly dependent on the nature of the support. Pranjal Saikia, Abu Taleb Miah, Banajit Malakar, and Ankur Bordoloi Copyright © 2015 Pranjal Saikia et al. All rights reserved. Synthesis and Optical Characterization of Europium Doped MY2O4 (M = Mg, Ca, and Sr) Nanophosphors for Solid State Lightening Applications Mon, 17 Aug 2015 11:57:07 +0000 Trivalent europium doped yttriate nanophosphors were synthesized by rapid facile gel combustion technique. The photoluminescence (PL) properties of these Eu3+ activated MY2O4 (M = Mg, Ca, and Sr) nanophosphors showed red luminescence and exhibited excellent emission properties in their respective regions of color coordinates. Based on the excitation wavelengths multiple emission peaks were obtained. The main peak in the emission spectra was ascribed to 5D0→7F2 transition of Eu3+ ion. The structural and morphological studies were performed by the measurements of X-ray diffraction profiles, scanning electron microscope (SEM) images, and transmission electron microscope (TEM) micrographs. Furthermore, the effects of additional heating on the different host lattices of these phosphors were also studied. Devender Singh, Vijeta Tanwar, Shri Bhagwan, Vandna Nishal, Suman Sheoran, Sonika Kadyan, Anura P. Samantilleke, and Pratap Singh Kadyan Copyright © 2015 Devender Singh et al. All rights reserved. Combined Effect of Slip Velocity and Surface Roughness on a Magnetic Squeeze Film for a Sphere in a Spherical Seat Tue, 11 Aug 2015 07:46:44 +0000 This investigation analyzes the performance of a magnetic fluid based squeeze film for a sphere in a rough spherical seat with slip velocity. The slip model of Beavers and Joseph has been deployed to study the effect of velocity slip while the stochastic model of Christensen and Tonder has been used to calculate the effect of surface roughness. The concerned statistically averaged Reynolds’ type equation is solved to derive the pressure distribution which results in the calculation of load carrying capacity. The results presented in graphical forms confirm that the adverse effect of slip velocity can be overcome to a large extent at least in the case of negatively skewed roughness. However, lower values of slip may be preferred for enhancing the performance characteristics of the bearing system. Besides, variance (−ve) provides a little support to improve the performance characteristics. G. M. Deheri and Sejal J. Patel Copyright © 2015 G. M. Deheri and Sejal J. Patel. All rights reserved. Effects of M2+ (M = Ca, Sr, and Ba) Addition on Crystallization and Microstructure of SiO2-MgO-Al2O3-B2O3-K2O-F Glass Wed, 05 Aug 2015 16:57:35 +0000 In understanding the effect of K+ substitution by M2+ (M = Ca, Sr, and Ba) on crystallization and microstructural properties of boroaluminosilicate glass system, the SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glasses were prepared by single-step melt-quenching at 1500°C. Density of base glass (2.64 g·cm−3) is found to be decreased in presence of CaO and SrO. is increased by 5–10°C and decreased by 13–20°C on addition of M2+. The variation of , and decrease of thermal expansion (CTE) from 7.55 to 6.67–6.97 (×10−6/K, at 50–500°C) in substituting K+ by M2+ are attributed to the higher field-strength of Ca2+, Sr2+, and Ba2+. Opaque mica glass-ceramics were derived from the transparent boroaluminosilicate glasses by controlled heat treatment at 1050°C (duration = 4 h); and the predominant crystalline phase was identified as fluorophlogopite (KMg3AlSi3O10F2) by XRD and FTIR study. Glass-ceramic microstructure reveals that the platelike mica flake crystals predominate in presence of K2O and CaO but restructured to smaller droplet like spherical shaped mica on addition of SrO and BaO. Wide range of CTE values (9.54–13.38 × 10−6/K at 50–800°C) are obtained for such glass-ceramics. Having higher CTE value after crystallization, the CaO containing SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glass can be useful as SOFC sealing material. Mrinmoy Garai, Nibedita Sasmal, and Basudeb Karmakar Copyright © 2015 Mrinmoy Garai et al. All rights reserved. Electronic Structure, Electronic Charge Density, and Optical Properties Analysis of GdX3 (X = In, Sn, Tl, and Pb) Compounds: DFT Calculations Mon, 03 Aug 2015 07:36:33 +0000 The electronic properties of magnetic cubic AuCu3 type GdX3 (X = In, Sn, Tl, and Pb) have been studied using first principles calculations based on density functional theory. Because of the presence of strong on-site Coulomb repulsion between the highly localized 4f electrons of Gd atoms, we have used LSDA + U approach to get accurate results in the present study. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The calculated density of states at the Fermi level N() shows good agreement with the available experimental results. The calculated electronic charge density plots show the presence of ionic bonding in all the compounds along with partial covalent bonding except in GdIn3. The complex optical dielectric function’s dispersion and the related optical properties such as refractive indices, reflectivity, and energy-loss function were calculated and discussed in detail. Jisha Annie Abraham, Gitanjali Pagare, and Sankar P. Sanyal Copyright © 2015 Jisha Annie Abraham et al. All rights reserved. Effect of Crystallinity of β- and βbc-Nickel Hydroxide Samples on Chemical Cycling Mon, 27 Jul 2015 08:02:32 +0000 β-phases of nickel hydroxide and cobalt hydroxide samples crystallize in cadmium iodide type structure. β-cobalt hydroxide on oxidation generates β-CoOOH which crystallized in 3R1 polytype while the structure of β-phase of NiOOH polytype is less well understood. β- and -phases of nickel hydroxide samples were prepared by using ammonium hydroxide and sodium hydroxide as precipitating agents. Powder X-ray diffraction data shows that β-phase of nickel hydroxide is perfectly crystalline in nature while -phase of nickel hydroxide is poorly ordered. β- and -phases of nickel hydroxide samples were subjected to chemical oxidation using sodium hypochlorite. The oxidized phases of β- and -phases of nickel oxyhydroxide are highly disordered and the broadening of reflections in the powder X-ray diffraction patterns is due to the presence of structural disorder, variations in the crystallite size, and strain. On reduction of β- and -phases of nickel oxyhydroxide, the powder X-ray diffraction patterns visually match the powder X-ray diffraction data of the pristine phases of β- and -phases of nickel hydroxide indicating that the β-phase of nickel hydroxide does not transform to -phase of nickel hydroxide, but the particle sizes are significantly affected. Ramesh Thimmasandra Narayan Copyright © 2015 Ramesh Thimmasandra Narayan. All rights reserved. Improvement in Tribological Performance of Ni-P-TiO2 Composite Coatings Using Taguchi Technique with Grey Relational Analysis Sun, 26 Jul 2015 09:28:24 +0000 Tribological performance of Ni-P-TiO2 composite coatings is improved by varying the tribological test parameters such as normal load, wear track diameter, and duration of test aiming at minimum wear and friction of the coating. Taguchi technique with grey relational analysis is employed for optimization of multiresponse problem using orthogonal array (OA). Analysis of variance (ANOVA) is used to find out the significant effect of test parameters and their interactions on friction and wear behavior of the coating. ANOVA results reveal that normal load and time (test duration) have the most significant effect in controlling wear and friction of the coating. Interaction between normal load and wear track diameter has some significant effect. Scanning electron microscopy of worn surface shows abrasive wear to be predominant. The surface morphology, composition, and phase structure analysis are done with the help of scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD) analysis, respectively. Prasanna Gadhari and Prasanta Sahoo Copyright © 2015 Prasanna Gadhari and Prasanta Sahoo. All rights reserved. Synthesis, Crystallization, and Dielectric Behaviour of Lead Bismuth Titanate Borosilicate Glasses with Addition of 1% La2O3 Wed, 15 Jul 2015 07:54:03 +0000 Lead bismuth titanate borosilicate glasses were prepared in the glass system 65[()·TiO3]-34[2SiO2·B2O3]-1La2O3 () doped with one mole percent of via conventional melt quench method. The amorphous nature of glass samples in this glass system is confirmed by using X-ray diffraction (XRD) study. Differential thermal analysis (DTA) has been employed to determine the glass transition temperature, , as well as crystallization temperature, . DTA measurements were recorded in temperature range from 30 to 1200°C. The prepared glasses were crystallized by regulated controlled heat treatment process on the basis of their DTA results. These samples are carried out for XRD measurements in the 2 range from 20 to 80° to study the crystallization behaviour and phase formation of the glass ceramic samples. The scanning electron microscopy (SEM) of these glass ceramic samples has been carried out to explore the morphology through nucleation and growth of the crystallites in the glassy matrix. The values of dielectric constant as well as dielectric loss were increased with increasing the temperature within the frequency range from 20 Hz to 100 Hz. The addition of 1 mol% of to the lead bismuth titanate glasses enhances the crystallization and acts as donor dopant for this glass system. C. R. Gautam, Abhishek Madheshiya, and R. K. Dwivedi Copyright © 2015 C. R. Gautam et al. All rights reserved. SH-Wave at a Plane Interface between Homogeneous and Inhomogeneous Fibre-Reinforced Elastic Half-Spaces Thu, 09 Jul 2015 07:21:42 +0000 The problem of reflection and refraction of SH-waves at a plane interface between the homogeneous and inhomogeneous fibre-reinforced elastic half-spaces has been investigated. Amplitude and energy ratios corresponding to the reflected and refracted SH-waves are derived using appropriate boundary conditions. These ratios are computed numerically for a particular model and the results are depicted graphically. C. Zorammuana and S. S. Singh Copyright © 2015 C. Zorammuana and S. S. Singh. All rights reserved. Simple Rheological Analysis Method of Spinnable-Polymer Flow Properties Using MFI Tester Sun, 05 Jul 2015 08:57:25 +0000 Rheological characterization of polymers explains the flow behaviour and viscoelastic properties and tests fibre-forming ability. The current method investigates the viscoelastic properties and morphology of polymers and finds the rheological data and the right polymer viscosity, which is determining the best processing temperature. The right processing temperature saves the power, the material, and the time needed for production. After calculating polymers viscosity by using MFI tester, the method investigates rheological properties and surface shape at different temperatures and loads. The method could apply to other polymers to find the viscosity-temperature change and to set the best processing temperature. Basel Younes Copyright © 2015 Basel Younes. All rights reserved. Simple Hydrolysis Synthesis of Uniform Rice-Shaped β-FeOOH Nanocrystals and Their Transformation to α-Fe2O3 Microspheres Sun, 05 Jul 2015 08:43:12 +0000 In the synthesis of nanostructure materials a specific emphasis has been focused on the control of shape and orientation of nanocrystals to obtain prerequisite properties of the materials. Nanorice is a new hybrid nanoparticle prolate geometry of nanoshells with reduced symmetry having new exciting optical behavior. Rice-shaped β-FeOOH nanocrystals have been synthesized by a simple hydrolysis chemical method using ferric aqueous solution and urea as surfactant. The successive calcination of β-FeOOH nanocrystals at 650°C results in the formation of the porous α-Fe2O3 (hematite) microspheres. The as-synthesized yield of β-FeOOH nanocrystals was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), and optical spectroscopy. The successive transformation of rice-shaped β-FeOOH nanostructures into porous α-Fe2O3 (hematite) microspheres through calcination process was confirmed by XRD, SEM, and EDAX studies. The water contact angle of as-prepared α-Fe2O3 microspheres shows hydrophobic behavior of the material. Beer Pal Singh, Nansy Sharma, Rakesh Kumar, and Ashwani Kumar Copyright © 2015 Beer Pal Singh et al. All rights reserved. Modification of Grout Properties in Prepacked Aggregate Concrete Incorporating Palm Oil Fuel Ash Thu, 18 Jun 2015 06:52:28 +0000 Prepacked aggregate concrete (PAC) is a type of concrete that is placed in two stages where the coarse aggregates are first placed inside the formworks and then the grout is pumped from underneath through a manual pump. Grout properties including density, grout consistency, bleeding, and compressive strength are of great importance in PAC. Such properties could be improved by application of pozzolanic materials like palm oil fuel ash. This paper is aimed at finding the most optimum percentage of POFA replacement by weight of cement. It was concluded that 30% POFA replacement yielded the most optimum results. Reza Hodjati, Hossein Aslani, Iman Faridmehr, A. S. M. Abdul Awal, and Ziba Kazemi Copyright © 2015 Reza Hodjati et al. All rights reserved. Structural, Optical, Electrical, and Magnetic Properties of PVA:Gd3+ and PVA:Ho3+ Polymer Films Wed, 27 May 2015 14:09:33 +0000 Polymer films of PVA:Gd3+ and PVA:Ho3+ have been synthesized by a solution casting method in order to study their structural, optical, electrical, and magnetic properties. The semicrystalline nature of the polymer films has been confirmed from XRD analysis. The FTIR analysis confirms the complex formation of the polymer with the metal ions. Dielectric studies of these films have also been carried out at various set temperatures in the frequency from 100 Hz to 1 MHz for carrying out impedance spectroscopy analysis to evaluate the electrical conductivity which arises due to a single conduction mechanism and thus to have a single semicircle pattern from these polymer films. The DC electrical conductivity increases with an increase in the temperature and it could be due to high mobility of free charges (polarons and free ions) at higher temperatures. The conductivity trend follows the Arrhenius equation for PVA:Gd3+ and for PVA:Ho3+ polymer films. PVA:Gd3+ polymer films show ferromagnetic nature, and PVA:Ho3+ polymer films have revealed paramagnetic nature based on the trends noticed in the magnetic characteristic profiles. M. Obula Reddy and B. Chandra Babu Copyright © 2015 M. Obula Reddy and B. Chandra Babu. All rights reserved. Simulation of Ni-Based Super-Alloy and Optimizing of Its Mechanical Properties in a Near-Shaped Turbine Blade Part Wed, 15 Apr 2015 12:43:24 +0000 This paper presents simulation of a Ni-based super-alloy during filling of a near-shaped turbine blade part to optimize its mechanical properties. Since geometrical shape of the airfoil is so complicated, a simple near-shaped part was made by plexiglass to water modeling. Condition and parameters of water modeling were obtained from the Procast software simulation. The flow pattern of the transparent systems, recorded by a high speed video camera, was analyzed. Air bubble amounts were quantitatively measured by an image analysis software. Quantified results were used to compare two systems in terms of ability to prevent bubble formation and entrainment. Both water modeling and computer simulating methods indicated that highest turbulences in bottom- and top-poured systems form in first initially pouring times. According to the water modeling results amount of bubble values was 40 and 18 percent for top-poured and bottom-poured systems, respectively. Then the Ni-base super-alloy IN939 is poured by investment casting in bottom- and top-poured systems and compared with each other. The results stated that bottom-poured system had higher mechanical properties compared to top-poured one. Ultimate tensile strength for the former was 820 MPa while for the part which was cast by bottom-poured system it was 850 MPa. Mohammd Reza Alizadeh Copyright © 2015 Mohammd Reza Alizadeh. All rights reserved. Effect of Fiber Treatment and Fiber Loading on Mechanical Properties of Luffa-Resorcinol Composites Thu, 05 Mar 2015 07:50:51 +0000 Tensile and compressive behaviour of resorcinol-formaldehyde (RF) matrix and its composites reinforced with fibers of Luffa cylindrica (LC) have been studied. LC fibers were subjected to chemical treatments such as alkali activation by NaOH followed by bleaching and acid hydrolysis in order to improve fiber-matrix adhesion. Both treated and untreated LC fibers are modified with calcium phosphate. The presence of hydroxy apatite, a polymorph of calcium phosphate and a major constituent of vertebrate bone and teeth, was confirmed from XRD peak of treated LC fiber. XRD analysis of the treated LC fiber has confirmed the crystalline nature of the chemically treated LC fiber by its crystallinity index. The effects of fiber loading of chemically treated and untreated LC fiber on ultimate stress, yield strength, breaking stress, and modulus of the composites were analyzed. The tensile and compressive modulus of the composites were increased with incorporation of both treated and untreated LC fibers into the RF matrix. The modulus of composites with treated LC fiber was enhanced compared to that of the untreated fiber composites. Furthermore the values of ultimate stress, yield stress, and breaking stress were increased with the incorporation of treated LC fiber in the composites. Chhatrapati Parida, Sarat Kumar Dash, and Sarat Chandra Das Copyright © 2015 Chhatrapati Parida et al. All rights reserved. Influence of Al and Ti Additions on Microstructure and Mechanical Properties of Leaded Brass Alloys Wed, 16 Jul 2014 00:00:00 +0000 Brass has an attractive combination of properties, namely, good corrosion resistance, good wear properties, and high thermal and electrical conductivity. In this study, influence of selected alloy additions (Al and Ti) on performance of leaded brass alloys (CuZn39pb3) was investigated. The observation of microstructures, compression tests, and hardness tests were performed. The results of metallographic and mechanical tests indicate some influence of small amount additives of Al and Ti. Optical emission spectrometer (OES), light optical microscope (LOM), micro-Vickers hardness tester, and compression testing machine were used in this investigation. Consequently, Al had a significant effect on microstructure and mechanical properties of CuZn39Pb3 alloy. A larger compression strength at 0.31% wt of Al was obtained, as compared with the other alloys. Adding of Al and Ti led to the modification of the microstructure; thus, the compression strength was increased. Rajab Mohammed Hussein and Osama Ibrahim Abd Copyright © 2014 Rajab Mohammed Hussein and Osama Ibrahim Abd. All rights reserved. Effect of Rotation on Propagation of Waves in Transversely Isotropic Thermoelastic Half-Space Thu, 19 Jun 2014 07:47:37 +0000 The present study is concerned with the effect of rotation on the propagation of plane waves in a transversely isotropic medium in the context of thermoelasticity theory of GN theory of types II and III. After solving the governing equations, three waves propagating in the medium are obtained. The fastest among them is a quasilongitudinal wave. The slowest of them is a thermal wave. The remaining is called quasitransverse wave. The prefix “quasi” refers to their polarizations being nearly, but not exactly, parallel or perpendicular to the direction of propagation. The polarizations of these three waves are not mutually orthogonal. After imposing the appropriate boundary conditions, the amplitudes of reflection coefficients have been obtained. Numerically simulated results have been plotted graphically with respect to frequency to evince the effect of rotation and anisotropy. Raj Rani Gupta and Rajani Rani Gupta Copyright © 2014 Raj Rani Gupta and Rajani Rani Gupta. All rights reserved. Searching for Alternative Plasmonic Materials for Specific Applications Mon, 12 May 2014 13:22:18 +0000 The localized surface plasmon resonance (LSPR) based optical properties such as light scattering, absorption, and extinction efficiencies of multimetallic and metal-semiconductor nanostructures will be studied. The effect of size, surrounding medium, interaction between the particles, composition of the particles, and substrate on LSPR peak position, its line width, and maxima of cross-sections will also be discussed to optimize the selected systems for various applications like plasmonic sensors and biomedical applications and to enhance the efficiency of solar cells. Therefore, by varying all these factors, the LSPR peak of multimetallic and metal-semiconductor nanostructures can be tuned over the entire UV-visible to infrared (IR) region of the electromagnetic spectrum. Moreover the optical properties of underlying semiconductor materials can be enhanced by combining the semiconductor with noble metal nanoparticles. Amit Bansal and S. S. Verma Copyright © 2014 Amit Bansal and S. S. Verma. All rights reserved. Effect of Concentration of Sodium Hydroxide and Degree of Heat Curing on Fly Ash-Based Geopolymer Mortar Mon, 05 May 2014 12:09:02 +0000 Geopolymer concrete/mortar is the new development in the field of building constructions in which cement is totally replaced by pozzolanic material like fly ash and activated by alkaline solution. This paper presented the effect of concentration of sodium hydroxide, temperature, and duration of oven heating on compressive strength of fly ash-based geopolymer mortar. Sodium silicate solution containing Na2O of 16.45%, SiO2 of 34.35%, and H2O of 49.20% and sodium hydroxide solution of 2.91, 5.60, 8.10, 11.01, 13.11, and 15.08. Moles concentrations were used as alkaline activators. Geopolymer mortar mixes were prepared by considering solution-to-fly ash ratio of 0.35, 0.40, and 0.45. The temperature of oven curing was maintained at 40, 60, 90, and 120°C each for a heating period of 24 hours and tested for compressive strength at the age of 3 days as test period after specified degree of heating. Test results show that the workability and compressive strength both increase with increase in concentration of sodium hydroxide solution for all solution-to-fly ash ratios. Degree of heating also plays vital role in accelerating the strength; however there is no large change in compressive strength beyond test period of three days after specified period of oven heating. Subhash V. Patankar, Yuwaraj M. Ghugal, and Sanjay S. Jamkar Copyright © 2014 Subhash V. Patankar et al. All rights reserved. Analysis of Free Edge Stresses in Composite Laminates Using Higher Order Theories Sun, 04 May 2014 06:40:11 +0000 This paper presents the determination of the interlaminar stresses close to the free edges of general cross-ply composite laminates based on higher order equivalent single-layer theory (HESL). The laminates with finite dimensions were subjected to a bending moment, an axial force, and/or a torque for investigation. Full three-dimensional stresses in the interior and the boundary-layer regions were determined. The computed results were compared with those obtained from Reddy’s layerwise theory. It was found that HESL theory predicts precisely the interlaminar stresses near the free edges of laminates. Besides, high efficiency in terms of computational time is obtainable when HESL theory is used as compared with layerwise theory. Finally, various numerical results were presented for the cross-ply laminates. Also design guidelines were proposed to minimize the edge-effect problems in composite laminates. Hamidreza Yazdani Sarvestani and Ali Naghashpour Copyright © 2014 Hamidreza Yazdani Sarvestani and Ali Naghashpour. All rights reserved. Temperature Dependence of Thermoelastic Properties for NaCl Crystal Wed, 30 Apr 2014 00:00:00 +0000 Recently developed isothermal Kholiya’s EOS is modified to study the temperature dependent volume expansion and applied for NaCl crystal. The results obtained with the present model are in quite close agreement to the experimental values. The model is therefore extended to study the variation of bulk modulus and the coefficient of volume thermal expansion with temperature. Comparison of the obtained results with the experimental data demonstrates that an isothermal EOS may also be modified to study the temperature dependent elastic properties. The present study also reveals that the quasi harmonic approximation, that is, the product of bulk modulus and the coefficient of volume thermal expansion as constant, is valid in case of NaCl crystal. Kuldeep Kholiya and Jeewan Chandra Copyright © 2014 Kuldeep Kholiya and Jeewan Chandra. All rights reserved.