International Journal of Metals The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. A Comparative Study of the Inhibitory Effect of Gum Exudates from Khaya senegalensis and Albizia ferruginea on the Corrosion of Mild Steel in Hydrochloric Acid Medium Tue, 22 Dec 2015 14:08:49 +0000 A comparative study of the inhibitory potentials of gum exudates from Albizia ferruginea (AF) and Khaya senegalensis (KS) on the corrosion of mild steel in HCl medium was investigated using weight loss and gasometric method. The active chemical constituents of the gum were elucidated using GC-MS while FTIR was used to identify the bonds/functional groups in the gums. The two gum exudates were found to be good corrosion inhibitors for mild steel in acidic medium. On comparison, maximum inhibition efficiency was found in Khaya senegalensis with 82.56% inhibition efficiency at 0.5% g/L concentration of the gum. This may be due to the fact that more compounds with heteroatoms were identified in the GCMS spectrum of KS gum compared to the AF gum. The presence of such compounds may have enhanced their adsorption on the metal surface and thereby blocking the surface and protecting the metal from corrosion. The adsorption of the inhibitors was found to be exothermic and spontaneous and fitted the Langmuir adsorption model. Paul Ocheje Ameh Copyright © 2015 Paul Ocheje Ameh. All rights reserved. Effect of Alternating Bending on Texture, Structure, and Elastic Properties of Sheets of Magnesium Lithium Alloy Sun, 29 Nov 2015 12:29:01 +0000 The effect of low-cycle alternating bending at room temperature on the crystallographic texture, metallographic structure, and elastic properties of sheets of MgLi5 (mass) magnesium alloy after warm cross-rolling has been studied. Texture of alloy is differed from the texture of pure magnesium. The initial texture of alloy is characterized by a wide scatter of basal poles in the transverse direction. In the process of alternating bending, the changes in the initial texture and structure (which is represented by equiaxed grains containing twins) lead to regular changes in the anisotropy of elastic properties. N. M. Shkatulyak, S. V. Smirnova, and V. V. Usov Copyright © 2015 N. M. Shkatulyak et al. All rights reserved. Effects of Moulding Sand Permeability and Pouring Temperatures on Properties of Cast 6061 Aluminium Alloy Tue, 03 Nov 2015 09:16:43 +0000 Effects of moulding sand permeabilities prepared from the combinations of four proportions of coarse and fine particle size mixtures and pouring temperatures varied from 700, 750, and 800 (±10°C) were studied on the hardness, porosity, strength, and microstructure of cast aluminium pistons used in hydraulic brake master cylinder. Three sand moulds were prepared from each of the 80 : 20, 60 : 40, 40 : 60, and 20 : 80 ratios. The surfaces and microstructures of cast samples were examined using high resolution microscopic camera, metallurgical microscope with digital camera, and scanning electron microscope with EDX facilities. The best of the metallurgical properties were obtained from the combination of 80 : 20 coarse-fine sand ratio and 750 ± 10°C pouring temperature using as MgFeSi inoculant. An 8 : 25 ratio of coarse to fine grained eutectic aluminium alloy was obtained with enhanced metallographic properties. The cast alloy poured at 750 ± 1°C has a large number of fine grain formations assuming broom-resembling structures as shown in the 100 µm size SEM image. Olawale Olarewaju Ajibola, Daniel Toyin Oloruntoba, and Benjamin O. Adewuyi Copyright © 2015 Olawale Olarewaju Ajibola et al. All rights reserved. Numerical Investigations on Characteristics of Stresses in U-Shaped Metal Expansion Bellows Mon, 14 Sep 2015 11:30:25 +0000 Metal expansion bellows are a mechanical device for absorbing energy or displacement in structures. It is widely used to deal with vibrations, thermal expansion, and the angular, radial, and axial displacements of components. The main objective of this paper is to perform numerical analysis to find various characteristics of stresses in U-shaped metal expansion bellows as per the requirement of vendor and ASME standards. In this paper, extensive analytical and numerical study is carried out to calculate the different characteristics of stresses due to internal pressure varying from 1 MPa to 2 MPa in U-shaped bellows. Finite element analysis by using Ansys14 is performed to find the characteristics of U-shaped metal expansion bellows. Finally, the results of analytical analysis and finite element method (FEM) show a very good agreement. The results of this research work could be used as a basis for designing a new type of the metal bellows. S. H. Gawande, N. D. Pagar, V. B. Wagh, and A. A. Keste Copyright © 2015 S. H. Gawande et al. All rights reserved. Effect of Electrode Types on the Solidification Cracking Susceptibility of Austenitic Stainless Steel Weld Metal Wed, 12 Aug 2015 06:37:40 +0000 The effect of electrode types on the solidification cracking susceptibility of austenitic stainless steel weld metal was studied. Manual metal arc welding method was used to produce the joints with the tungsten inert gas welding serving as the control. Metallographic and chemical analyses of the fusion zones of the joints were conducted. Results indicate that weldments produced from E 308-16 (rutile coated), E 308-16(lime-titania coated) electrodes, and TIG welded joints fall within the range of and solidified with a duplex mode and were found to be resistant to solidification cracking. The E 308-16 weld metal had the greatest resistance to solidification cracking. Joints produced from E 310-16 had ratio < 1.5 and solidified with austenite mode. It was found to be susceptible to solidification cracking. E 312-16 produced joints having ratio > 1.9 and solidified with ferrite mode. It had a low resistance to solidification cracking. J. U. Anaele, O. O. Onyemaobi, C. S. Nwobodo, and C. C. Ugwuegbu Copyright © 2015 J. U. Anaele et al. All rights reserved. Microstructure, Strength, and Fracture Topography Relations in AISI 316L Stainless Steel, as Seen through a Fractal Approach and the Hall-Petch Law Mon, 27 Jul 2015 06:22:08 +0000 The influence of the fracture surface fractal dimension and the fractal dimension of grain microstructure on the strength of AISI 316L type austenitic stainless steel through the Hall-Petch relation has been studied. The change in complexity experimented by the net of grains, as measured by , is translated into the respective fracture surface irregularity through , in such a way that the higher the grain size (lower values) the lower the fracture surface roughness (lower values of ) and the shallower the dimples on the fractured surfaces. The material was heat-treated at 904, 1010, 1095, and 1194°C, in order to develop equiaxed grain microstructures and then fractured by tension at room temperature. The fracture surfaces were analyzed with a scanning electron microscope, was determined using the slit-island method, and the values of were taken from the literature. The relation between grain size, , mechanical properties, and , developed for AISI 316L steel, could be generalized and therefore applied to most of the common micrograined metal alloys currently used in many key engineering areas. Oswaldo Antonio Hilders, Naddord Zambrano, and Ramón Caballero Copyright © 2015 Oswaldo Antonio Hilders et al. All rights reserved. Response of Functionally Graded Material Plate under Thermomechanical Load Subjected to Various Boundary Conditions Sun, 15 Feb 2015 09:17:06 +0000 Functionally graded materials (FGMs) are one of the advanced materials capable of withstanding the high temperature environments. The FGMs consist of the continuously varying composition of two different materials. One is an engineering ceramic to resist the thermal loading from the high-temperature environment, and the other is a light metal to maintain the structural rigidity. In the present study, the properties of the FGM plate are assumed to vary along the thickness direction according to the power law distribution, sigmoid distribution, and exponential distribution. The fundamental equations are obtained using the first order shear deformation theory and the finite element formulation is done using minimum potential energy approach. The numerical results are obtained for different distributions of FGM, volume fractions, and boundary conditions. The FGM plate is subjected to thermal environment and transverse UDL under thermal environment and the response is analysed. Numerical results are provided in nondimensional form. Manish Bhandari and Kamlesh Purohit Copyright © 2015 Manish Bhandari and Kamlesh Purohit. All rights reserved. A Numerical Formula for General Prediction of Interface Bonding between Alumina and Aluminum-Containing Alloys Wed, 24 Dec 2014 08:53:16 +0000 Interface termination between alumina and aluminum-containing alloys is discussed from a viewpoint of thermodynamics by extending the authors’ previous discussion on the interface termination between alumina and pure metal. A numerical formula to predict interface bonding at alumina-aluminum-containing alloys is proposed. The effectiveness of the formula is examined by extracting information on interface termination from experimental results and first-principle calculations in references. It is revealed that the prediction by the formula agrees quite well with the results reported in the references. According to the formula, a terminating species can be switched from oxygen to aluminum, which had been actually demonstrated experimentally. The formula uses only basic quantities of pure elements and the formation enthalpy of oxides. Therefore it can be applied for most of aluminum-containing alloys in the periodic table and is useful for material screening in developing interfaces with particular functions. Michiko Yoshitake, Shinjiro Yagyu, and Toyohiro Chikyow Copyright © 2014 Michiko Yoshitake et al. All rights reserved. Corrosion Behavior of Carbon Steel in Synthetically Produced Oil Field Seawater Wed, 17 Dec 2014 06:04:32 +0000 The life of offshore steel structure in the oil production units is decided by the huge corrosive degradation due to , S2−, and Cl−, which normally present in the oil field seawater. Variation in pH and temperature further adds to the rate of degradation on steel. Corrosion behavior of mild steel is investigated through polarization, EIS, XRD, and optical and SEM microscopy. The effect of all 3 species is huge material degradation with FeSx and FeCl3 and their complex as corrosion products. EIS data match the model of Randle circuit with Warburg resistance. Addition of more corrosion species decreases impedance and increases capacitance values of the Randle circuit at the interface. The attack is found to be at the grain boundary as well as grain body with very prominent sulphide corrosion crack. Subir Paul, Anjan Pattanayak, and Sujit K. Guchhait Copyright © 2014 Subir Paul et al. All rights reserved. Herbal Plant Synthesis of Antibacterial Silver Nanoparticles by Solanum trilobatum and Its Characterization Sun, 30 Nov 2014 00:10:03 +0000 Green synthesis method of nanomaterials is rapidly growing in the nanotechnology field; it replaces the use of toxic chemicals and time consumption. In this present investigation we report the green synthesis of silver nanoparticles (AgNPs) by using the leaf extract of medicinally valuable plant Solanum trilobatum. The influence of physical and chemical parameters on the silver nanoparticle fabrication such as incubation time, silver nitrate concentration, pH, and temperature is also studied in this present context. The green synthesized silver nanoparticles were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray (EDX), and transmission electron microscope (TEM). The SEM and TEM confirm the synthesis of spherical shape of nanocrystalline particles with the size range of 2–10 nm. FTIR reveals that the carboxyl and amine groups may be involved in the reduction of silver ions to silver nanoparticles. Antibacterial activity of synthesized silver nanoparticles was done by agar well diffusion method against different pathogenic bacteria. The green synthesized silver nanoparticles can be used in the field of medicine, due to their high antibacterial activity. M. Vanaja, K. Paulkumar, G. Gnanajobitha, S. Rajeshkumar, C. Malarkodi, and G. Annadurai Copyright © 2014 M. Vanaja et al. All rights reserved. Material Properties of Wire for the Fabrication of Knotted Fences Wed, 26 Nov 2014 00:10:01 +0000 This paper describes the materials properties of galvanised fencing wire, as used in the fabrication of knotted wire fences. A range of physical properties are investigated: tensile strength, ductility in tension, Young’s modulus, three-point bending, and bending span. A range of commercially available wire products were tested. The results show that most, but not all, high tensile wire samples met the minimum tensile and ductility requirements. Young’s modulus results failed to provide any meaningful insights into wire quality. Flexural modulus results also failed to provide any insight into wire quality issues, with no statistically significant differences existing between acceptable and problematic wire batches. The implications are that premature fence failures are unlikely to be caused solely by reduced tensile properties. Existing test methods, including tensile strength and ductility, are somewhat incomplete, perhaps even unreliable, as measures of wire quality. Dirk J. Pons, Gareth Bayley, Christopher Tyree, Matthew Hunt, and Reuben Laurenson Copyright © 2014 Dirk J. Pons et al. All rights reserved. The Elastic Constants of the Single Crystal of the Mg-Zn-Zr-REM Alloy from the Data of the Elastic Anisotropy and the Texture of the Polycrystalline Sheet Thu, 13 Nov 2014 12:33:12 +0000 The measuring of the constants of single-crystals requires the availability of crystals of relatively big size. In this paper the elastic constants of the single crystals of magnesium alloy with zinc, zirconium, and rare earth metals (REM) were determined by means of the experimental anisotropy of Young’s modulus and integral characteristics of texture (ICT), which were found from pole figures. Using these constants the anisotropy of Young’s modulus of alloy sheet ZE10 was calculated. Deviation of calculated values from experimental values did not exceed 2%. S. V. San’kova, N. M. Shkatulyak, V. V. Usov, and N. A. Volchok Copyright © 2014 S. V. San’kova et al. All rights reserved. Modification of Magnesium Alloys by Ceramic Particles in Gravity Die Casting Thu, 30 Oct 2014 09:19:40 +0000 A critical drawback for the application of magnesium wrought alloys is the limited formability of semifinished products that arises from a strong texture formation during thermomechanical treatment. The ability of second phase particles embedded into the metal matrix to alter this texture evolution is of great interest. Therefore, the fabrication of particle modified magnesium alloys (particle content 0.5–1 wt.-%) by gravity die casting has been studied. Five different types of micron sized ceramic powders (AlN, MgB2, MgO, SiC, and ZrB2) have been investigated to identify applicable particles for the modification. Agglomeration of the particles is revealed to be the central problem for the fabrication process. The main factors that influence the agglomerate size are the particle size and the intensity of melt stirring. Concerning handling, chemical stability in the Mg-Al-Zn alloy system, settling and wetting in the melt, and formation of the microstructure in most cases, the investigated powders show satisfying properties. However, SiC is chemically unstable in aluminum containing alloys. The high density of ZrB2 causes large particles to settle subsequent to stirring resulting in an inhomogeneous distribution of the particles over the cast billet. Urs Haßlinger, Christian Hartig, Norbert Hort, and Robert Günther Copyright © 2014 Urs Haßlinger et al. All rights reserved. Thermodynamic Properties of LSCoO3 Mon, 29 Sep 2014 00:00:00 +0000 We have investigated the bulk modulus and thermal properties of () at temperatures probably for the first time by incorporating the effect of lattice distortions using the modified rigid ion model (MRIM). The calculated specific heat, thermal expansion, bulk modulus, and other thermal properties reproduce well with the available experimental data, implying that MRIM represents properly the nature of the pure and doped cobaltate. The specific heats are found to increase with temperature and decrease with concentration (x) for the present. The increase in Debye temperature () indicates an anomalous softening of the lattice specific heat because increase in T3-term in the specific heat occurs with the decrease of concentration (x). Rasna Thakur and N. K. Gaur Copyright © 2014 Rasna Thakur and N. K. Gaur. All rights reserved. Accumulative Roll Bonding of Pure Copper and IF Steel Tue, 23 Sep 2014 07:11:16 +0000 Severe plastic deformation is a new method to produce ultrafine grain materials with enhanced mechanical properties. The main objective of this work is to investigate whether accumulative roll bonding (ARB) is an effective grain refinement technique for two engineering materials of pure copper and interstitial free (IF) steel strips. Additionally, the influence of severely plastic deformation imposed by ARB on the mechanical properties of these materials with different crystallographic structure is taken into account. For this purpose, a number of ARB processes were performed at elevated temperature on the materials with 50% of plastic deformation in each rolling pass. Hardness of the samples was measured using microhardness tests. It was found that both the ultimate grain size achieved, and the degree of bonding depend on the number of rolling passes and the total plastic deformation. The rolling process was stopped in the 4th cycle for copper and the 10th cycle for IF steel, until cracking of the edges became pronounced. The effects of process temperature and wire-brushing as significant parameters in ARB process on the mechanical behaviour of the samples were evaluated. Saeed Tamimi, Mostafa Ketabchi, Nader Parvin, Mehdi Sanjari, and Augusto Lopes Copyright © 2014 Saeed Tamimi et al. All rights reserved. Static Response of Functionally Graded Material Plate under Transverse Load for Varying Aspect Ratio Mon, 30 Jun 2014 09:45:55 +0000 Functionally gradient materials (FGM) are one of the most widely used materials in various applications because of their adaptability to different situations by changing the material constituents as per the requirement. Nowadays it is very easy to tailor the properties to serve specific purposes in functionally gradient material. Most structural components used in the field of engineering can be classified as beams, plates, or shells for analysis purposes. In the present study the power law, sigmoid law and exponential distribution, is considered for the volume fraction distributions of the functionally graded plates. The work includes parametric studies performed by varying volume fraction distributions and aspect ratio. The FGM plate is subjected to transverse UDL (uniformly distributed load) and point load and the response is analysed. Manish Bhandari and Kamlesh Purohit Copyright © 2014 Manish Bhandari and Kamlesh Purohit. All rights reserved. Band Gap Engineering of Alloys Tue, 13 May 2014 11:14:46 +0000 The structural and electronic properties of the ternary alloys have been calculated using the full-potential linear muffin-tin-orbital (FP-LMTO) method based on density functional theory within local density approximation (LDA). The calculated equilibrium lattice constants and bulk moduli are compared with previous results. The concentration dependence of the electronic band structure and the direct and indirect band gaps are investigated. Moreover, the refractive index and the optical dielectric constant for are studied. The thermodynamic stability of the alloys of interest is investigated by means of the miscibility. This is the first quantitative theoretical prediction to investigate the effective masses, optical and thermodynamic properties for alloy, and still awaits experimental. Djillali Bensaid, Mohammed Ameri, Nadia Benseddik, Ali Mir, Nour Eddine Bouzouira, and Fethi Benzoudji Copyright © 2014 Djillali Bensaid et al. All rights reserved. Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique for Optical Investigation Mon, 14 Apr 2014 16:15:05 +0000 Solvent mixed spray pyrolysis technique has attracted a global interest in the synthesis of nanomaterials since reactions can be run in liquid state without further heating. Magnesium oxide (MgO) is a category of the practical semiconductor metal oxides, which is extensively used as catalyst and optical material. In the present study, MgO nanoparticles were successfully synthesized using a solvent mixed spray pyrolysis. The X-ray diffraction pattern confirmed the formation of MgO phase with an excellent crystalline structure. Debye-Scherrer equation is used for the determination of particle size, which was found to be 9.2 nm. Tunneling electron microscope analysis indicated that the as-synthesized particles are nanoparticles with an average particle size of 9 nm. Meanwhile, the ultraviolet-visible spectroscopy of the resulting product was evaluated to study its optical property via measurement of the band gap energy value. K. R. Nemade and S. A. Waghuley Copyright © 2014 K. R. Nemade and S. A. Waghuley. All rights reserved. Synthesis and Characterization of Highly Efficient Nickel Nanocatalysts and Their Use in Degradation of Organic Dyes Thu, 27 Feb 2014 07:20:10 +0000 The present study describes the synthesis of highly active and ordered structures of nickel nanocatalysts by a facile, green, and economically viable approach. The study reveals efficient catalytic activity for the degradation of a number of toxic organic dyes, such as eosin-B (EB), rose bengal (RB), eriochrome black-T (ECBT), and methylene blue (MB). The stable ordered nickel nanostructure (Ni NSs) arrays were prepared via a modified hydrazine reduction route with unique and controlled morphologies in a lyotropic liquid crystalline medium using a nonionic surfactant (Triton X-100). Characterization and optimization studies for the fabricated Ni NSs involving their surface binding interactions, size, and morphologies were carried out using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nazar Hussain Kalwar, Sirajuddin, Razium Ali Soomro, Syed Tufail Hussain Sherazi, Keith Richard Hallam, and Abdul Rauf Khaskheli Copyright © 2014 Nazar Hussain Kalwar et al. All rights reserved. Algae Mediated Green Fabrication of Silver Nanoparticles and Examination of Its Antifungal Activity against Clinical Pathogens Sun, 19 Jan 2014 14:13:59 +0000 Algae extract has the great efficiency to synthesize the silver nanoparticles as a green route. Brown seaweed mediates the synthesis of silver nanomaterials using extract of Sargassum longifolium. For the improved production of silver nanomaterials, some kinetic studies such as time incubation and pH were studied in this work. 10 mL of algal extract was added into the 1 mM AgNO3 aqueous solution. The pH and reaction time range were changed and the absorbance was taken for the characterization of the nanoparticles at various time intervals, and the high pH level shows the increased absorbance due to the increased nanoparticles synthesis. The synthesized silver nanoparticles were characterized by Scanning Electron Microscope (SEM) showing that the shape of the material is spherical, and X-Ray Diffraction value obtained from range of (1 1 1) confirmed synthesized silver nanoparticles in crystalline nature. TEM measurement shows spherical shape of nanoparticles. The Fourier Transmittance Infrared spectrum (FT-IR) confirms the presence of biocomponent in the algae extract which was responsible for the nanoparticles synthesis. The effect of the algal mediated silver nanoparticles against the pathogenic fungi Aspergillus fumigatus, Candida albicans, and Fusarium sp. S. longifolium mediated synthesized silver nanoparticles shows cheap and single step synthesis process and it has high activity against fungus. This green process gives the greater potential biomedical applications of silver nanoparticles. Shanmugam Rajeshkumar, Chelladurai Malarkodi, Kanniah Paulkumar, Mahendran Vanaja, Gnanadas Gnanajobitha, and Gurusamy Annadurai Copyright © 2014 Shanmugam Rajeshkumar et al. All rights reserved. A Preliminary Study on Adhesion on Steel Cylinder Filled with Aluminum Foam Mon, 23 Dec 2013 09:28:07 +0000 In the last decades, metallic foams found commercial and industrial interests, thanks to their physical properties combined with good mechanical characteristics. Metal foam structures are very light and they can be used to reduce the weight of machinery without compromising the mechanical behavior. In this work, a study of the direct junction of metal foam with metal massive components was carried out. Aluminium foams were manufactured starting from commercial foamable precursors. First of all, attention was paid to the repeatability of foaming process. Then, a direct connection between the foamed samples and the steel shell elements was pursued. The materials that seemed to facilitate the formation of an intermetallic layer were studied and the geometry of the steel mould and the most useful way to place the precursor in the steel mould and then in the furnace were considered. To evaluate the produced aluminum foam, morphological and mechanical characterizations were done. Results showed that, keeping constant the contour conditions, it was possible to control the process and a first result, in terms of interaction between foam and mould, was obtained using an X210Cr12 steel as mould material. The SEM observation revealed the presence of an intermetallic phase. G. Marinzuli, L. A. C. De Filippis, R. Surace, and A. D. Ludovico Copyright © 2013 G. Marinzuli et al. All rights reserved. Optimization of Conversion Treatment on Austenitic Stainless Steel Using Experimental Designs Wed, 18 Dec 2013 09:51:02 +0000 Conversion coating is commonly used as treatment to improve the adherence of ceramics films. The conversion coating properties depend on the structure of alloy as well as on the treatment parameters. These conversion coatings must be characterized by strong interfacial adhesion, high roughness, and high real surface area, which were measured by an electrochemical method. The influence of all the elaboration factors (temperature, time, and bath composition: sulphuric acid, thiosulphate as accelerator, propargyl alcohol as inhibitor, and surface state) and also the interactions between these factors were evaluated, using statistical experimental design. The specific surface area and optical factor (α) correspond to the quantitative responses. The evaluation showed, by using a designed experimental procedure, that the most important factor was “surface state.” Sanded surface allows the formation of conversion coating with high real surface area. A further aim was to optimise two parameters: treatment time and temperature using Doehlert shell design and simplex method. The growth of the conversion coating is also influenced by treatment time and temperature. With such optimized conditions, the real surface area of conversion coating obtained was about 235 m2/m2. S. El Hajjaji, C. Cros, and L. Aries Copyright © 2013 S. El Hajjaji et al. All rights reserved. Nonlinear Optical Properties of Novel Mono-O-Hydroxy Bidentate Schiff Base: Quantum Chemical Calculations Tue, 17 Dec 2013 15:39:32 +0000 The semiempirical AM1 SCF method is used to study the first static hyperpolarizabilities of some novel mono-O-Hydroxy bidentate Schiff base in which electron donating (D) and electron accepting (A) groups were introduced on either side of the Schiff base ring system. Geometries of all molecules were optimized at the semiempirical AM1. The first static hyperpolarizabilities of these molecules were calculated using Hyperchem package. To understand this phenomenon in the context of molecular orbital picture, we examined the molecular HOMO and molecular LUMO generated via Hyperchem. The study reveals that the mono-O-Hydroxy bidentate Schiff bases have large values and hence in general may have potential applications in the development of nonlinear optical materials. N. S. Labidi Copyright © 2013 N. S. Labidi. All rights reserved. Optical Characteristics of Polystyrene Based Solid Polymer Composites: Effect of Metallic Copper Powder Thu, 12 Dec 2013 10:27:25 +0000 Solid polymer composites (SPCs) were prepared by solution cast technique. The optical properties of polystyrene doped with copper powder were performed by means of UV-Vis technique. The optical constants were calculated by using UV-Vis spectroscopy. The dispersion regions were observed in both absorption and refractive index spectra at lower wavelength. However, a plateau can be observed at high wavelengths. The small extinction coefficient compared to the refractive index reveals the transparency of the composite samples. The refractive index and optical band gap were determined from the reflectance and optical absorption coefficient data, respectively. The nature of electronic transition from valence band to conduction band was determined and the energy band gaps of the solid composite samples were estimated. It was observed that, upon the addition of Cu concentration, the refractive index increased while the energy gaps are decreased. The calculated refractive indexes (low index of refraction) of the samples reveal their availability in waveguide technology. Shujahadeen B. Aziz, Sarkawt Hussein, Ahang M. Hussein, and Salah R. Saeed Copyright © 2013 Shujahadeen B. Aziz et al. All rights reserved. Spectroscopic Study of Al3+-Substituted Strontium Hexaferrite Tue, 10 Dec 2013 11:03:41 +0000 The substituted Y type hexaferrites (where  = 2, 4, 6, 10) are prepared by standard ceramic technique. The infrared absorption spectra of the prepared compounds are studied in the range 400 cm−1 to 4600 cm−1. These spectra are used to locate the vibrational ranges due to substituted cations with the nearest oxygen layers and also to understand the band positions attributed to the lattice sites. The absorption regions found around 460 cm−1 and 600 cm−1 are the common features of all spinel ferrites. Both X-ray and IR spectroscopic studies in these ferrites do not detect the presence of Fe2+. Also with increase in aluminium substitution, the higher frequency bands start disappearing. This may be due to reduced vibrations of trivalent cations Fe–O bonds at both octahedral and tetrahedral sites which in turn affect Fe3+–O2−–Fe3+ superexchange interactions present in the structure. M. Y. Salunkhe, D. S. Choudhary, and S. B. Kondawar Copyright © 2013 M. Y. Salunkhe et al. All rights reserved. Effects of Heat Treatment on the Mechanical Properties of Al-4% Ti Alloy Mon, 09 Dec 2013 14:41:48 +0000 This paper examines the effects of heat treatment processes on the mechanical properties of as-cast Al-4% Ti alloy for structural applications. Heat treatment processes, namely, annealing, normalizing, quenching, and tempering, are carried out on the alloy samples. The mechanical tests of the heat treated samples are carried out and the results obtained are related to their optical microscopy morphologies. The results show that the heat treatment processes have no significant effect on the tensile strength of the as-cast Al-4% Ti alloy but produce significant effect on the rigidity and strain characteristic of the alloy. With respect to the strain characteristics, significant improvement in the ductility of the samples is recorded in the tempered sample. Thus, for application requiring strength and ductility such as in aerospace industries, this tempered heat treated alloy could be used. In addition, the quenched sample shows significant improvement in hardness. Segun Isaac Talabi, Samson Oluropo Adeosun, Abdulganiyu Funsho Alabi, Ishaq Na'Allah Aremu, and Sulaiman Abdulkareem Copyright © 2013 Segun Isaac Talabi et al. All rights reserved. Synthesis and Characterization of by Standard Ceramic Method Sun, 08 Dec 2013 15:20:56 +0000 The polycrystalline compounds with chemical formula (CSBFLO) were synthesized via standard ceramic method. The chemical phase analysis was carried out by X-ray powder diffraction (XRD) method, which confirmed the formation of the magnetoplumbite phase belonging to ferrite structure. The frequency dependence of AC conductivity and dielectric constant was studied in the frequency range of 10 Hz to 2 MHz. The experimental results revealed that AC conductivity increases with increasing frequency, which is in agreement with Koop’s phenomenological theory. However, variation in dielectric constant required explanation in light of dielectric polarization. Magnetic characterization included studies of parameters such as Ms, Mr, Hc, and Tc, and results were explained via magnetic dilution and canting spin structure. Rohit K. Mahadule, Purushottam R. Arjunwadkar, and Megha P. Mahabole Copyright © 2013 Rohit K. Mahadule et al. All rights reserved. Experimental Investigation of the Corrosion Behavior of Friction Stir Welded AZ61A Magnesium Alloy Welds under Salt Spray Corrosion Test and Galvanic Corrosion Test Using Response Surface Methodology Sat, 24 Aug 2013 13:02:46 +0000 Extruded Mg alloy plates of 6 mm thick of AZ61A grade were butt welded using advanced welding process and friction stir welding (FSW) processes. The specimens were exposed to salt spray conditions and immersion conditions to characterize their corrosion rates on the effect of pH value, chloride ion concentration, and corrosion time. In addition, an attempt was made to develop an empirical relationship to predict the corrosion rate of FSW welds in salt spray corrosion test and galvanic corrosion test using design of experiments. The corrosion morphology and the pit morphology were analyzed by optical microscopy, and the corrosion products were examined using scanning electron microscope and X-ray diffraction analysis. From this research work, it is found that, in both corrosion tests, the corrosion rate decreases with the increase in pH value, the decrease in chloride ion concentration, and a higher corrosion time. The results show the usage of the magnesium alloy for best environments and suitable applications from the aforementioned conditions. Also, it is found that AZ61A magnesium alloy welds possess low-corrosion rate and higher-corrosion resistance in the galvanic corrosion test than in the salt spray corrosion test. A. Dhanapal, S. Rajendra Boopathy, V. Balasubramanian, K. Chidambaram, and A. R. Thoheer Zaman Copyright © 2013 A. Dhanapal et al. All rights reserved. First Principles Study of Electronic Structure and Magnetic Properties of TMH (TM = Cr, Mn, Fe, Co) Sun, 14 Jul 2013 09:38:20 +0000 First principles calculations are performed using a tight-binding linear muffin-tin orbital (TB-LMTO) method with local density approximation (LDA) and atomic sphere approximation (ASA) to understand the electronic properties of transition metal hydrides (TMH) (TM = Cr, Mn, Fe, Co). The structural property, electronic structure, and magnetic properties are investigated. A pressure induced structural phase transition from cubic to hexagonal phase is predicted at the pressures of 50 GPa for CrH and 23 GPa for CoH. Also, magnetic phase transition is observed in FeH and CoH at the pressures of 10 GPa and 180 GPa, respectively. S. Kanagaprabha, R. Rajeswarapalanichamy, and K. Iyakutti Copyright © 2013 S. Kanagaprabha et al. All rights reserved. An Analytical Model Approach for the Dissolution Kinetics of Magnesite Ore Using Ascorbic Acid as Leaching Agent Wed, 26 Jun 2013 16:31:29 +0000 Ascorbic acid was used as leaching agent to investigate the dissolution kinetics of natural magnesite ore. The effects of various reaction parameters such as acid concentration, liquid-solid ratio, particle size, stirring speed, and temperature were determined on dissolution kinetics of the magnesite ore. It was found that the dissolution rate increased with increase in acid concentration, liquid-solid ratio, stirring speed, and temperature and decrease in the particle size of the ore. The graphical and statistical methods were applied to analyze the kinetic data, and it was evaluated that the leaching process was controlled by the chemical reaction, that is, . The activation energy of the leaching process was found to be 57.244 kJ mol−1 over the reaction temperature range from 313 to 343 K. Nadeem Raza, Zafar Iqbal Zafar, and Najam-ul-Haq Copyright © 2013 Nadeem Raza et al. All rights reserved.