International Journal of Metals
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Open Access journal
ISSN (Print) 2356-704X - ISSN (Online) 2314-680X
Published by Hindawi [333 journals]
- Improving Thin Strip Profile Using Work Roll Cross and Work Roll Shifting
Methods in Cold Strip Rolling
Abstract: The optimization of rolling parameters in order to achieve better strip shape and to reduce rolling force is a challenge in rolling practice. In this paper, thin strip asymmetrical rolling of aluminum at various speed ratios under lubricated condition has been investigated at various combinations of work rolls cross (WRC) angles and work rolls shifting (WRS) values. The effects of strip width, reduction, and rolling speed on strip shape taking WRC and WRS into consideration are discussed. Results show that strip profile improves significantly when the WRC angle is increased from 0° to 1°, with an associated reduction in rolling force. Increasing WRS value from 0 to 8 mm improves the strip profile as well but not as significantly as when WRC angle is increased. No significant improvement was found in strip shape when the strip width was increased. At higher reduction, the strip shape was improved; a decrease in the rolling force was also observed. A higher speed ratio was found to be effective only at a higher WRC angle. The effect of lubrication on the strip profile was significant. Results indicate that an optimum combination of WRC, WRS, reduction, width, and speed ratio under lubricated conditions can ensure an improved exit strip profile, reduce rolling force, and obtain a better quality strip.
PubDate: Mon, 09 Jan 2017 00:00:00 +000
- Interaction of Two Water Soluble Heterocyclic Hydrazones on Copper in
Nitric Acid: Electrochemical, Surface Morphological, and Quantum Chemical
Abstract: Two novel heterocyclic compounds (E)-2-(1-(pyridin-3-yl)ethylidene)hydrazinecarbothioamide (3APTSC) and (E)-3-(1-(2-phenylhydrazono)ethyl)pyridine (3APPH) derived from 1-(pyridin-3-yl)ethanone were synthesized and characterized by various spectroscopic techniques. The corrosion inhibition efficacies of these compounds on copper in 0.1 M HNO3 were screened by electrochemical corrosion monitoring techniques such as potentiodynamic polarization studies and impedance spectroscopy. Investigations clearly established that 3APPH displayed higher corrosion inhibition efficiency on Cu than 3APTSC at all concentrations. The mechanism of inhibition was verified with the help of adsorption isotherms. 3APTSC and 3APPH obeyed Langmuir adsorption isotherm on Cu surface. Thermodynamic parameters such as adsorption equilibrium constant () and free energy of adsorption () were also evaluated. Potentiodynamic polarization investigations confirmed that the 3APTSC and 3APPH act as mixed type inhibitors. Surface analysis of the metal specimens was performed by scanning electron microscopy. Energy of HOMO and LUMO, their difference, number of electrons transferred, electronegativity, chemical hardness, and so forth were evaluated by quantum chemical studies. Agreeable correlation was observed between the results of quantum chemical calculations and other corrosion monitoring techniques.
PubDate: Thu, 10 Nov 2016 06:17:52 +000
- An Ecofriendly Initiative for the Corrosion Inhibition of Mild Steel in
1 M HCl Using Tecoma capensis Flower Extract
Abstract: Corrosion inhibition of mild steel in 1 M HCl in the presence of Tecoma capensis flower extract was carried out by means of mass loss, potentiodynamic polarisation, and electrochemical impedance techniques. The inhibition efficiency varied with concentration of the inhibitor, immersion time, and temperature. The adsorption of the inhibitor on mild steel surface obeys Langmuir’s adsorption isotherm. Thermodynamic parameters reveal that the adsorption process is spontaneous. Electrochemical studies reflect that the inhibitor acts as a mixed-type inhibitor. Surface analytical techniques ascertain the inhibitive nature of the studied inhibitor.
PubDate: Mon, 31 Oct 2016 06:29:25 +000
- A Novel NDT Method for Coercive Force of Grain-Oriented Electrical Steel
Applied in Cigarette Machines
Abstract: Coercive force of grain-oriented electrical steel applied in cigarette machines is tested by a novel NDT method in which Barkhausen noise was applied. Linear relationship between coercive force and Barkhausen noise of conventional and high-permeability electrical steel was built and the precision of the model was verified. Experimental results show that the coercive force is linearly related to Barkhausen noise. The variation of coercive force with magnetic induction intensity increase was also interpreted in view of magnetic domain changing process, and the correlation formula derivation of MBN and coercive force domain wall was illustrated as well.
PubDate: Thu, 25 Aug 2016 16:30:04 +000
- Effect of the Strain Kind on the Texture and Microstructure of Low-Alloyed
Abstract: Crystallographic texture and microstructure of low-alloyed steel after twist extrusion (TE) and subsequent cold rolling along and across the TE axis were studied. The double axial cylindrical texture with axes and parallel to the TE axis and the vortex-like microstructure are formed in the steel during the TE. The subsequent rolling of extruded steel along the TE axis promotes the forming of typical steel rolling texture as well as the microstructure with elongated grains in rolling direction. Typical steel rolling texture as well as the equiaxed microstructure is formed in extruded steel after rolling in the direction transverse to the TE axis. The mechanisms of formation of the texture are discussed.
PubDate: Wed, 20 Jul 2016 16:52:30 +000
- 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
Abstract: 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.
PubDate: Tue, 22 Dec 2015 14:08:49 +000
- Effect of Alternating Bending on Texture, Structure, and Elastic
Properties of Sheets of Magnesium Lithium Alloy
Abstract: 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.
PubDate: Sun, 29 Nov 2015 12:29:01 +000
- Effects of Moulding Sand Permeability and Pouring Temperatures on
Properties of Cast 6061 Aluminium Alloy
Abstract: 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.
PubDate: Tue, 03 Nov 2015 09:16:43 +000
- Numerical Investigations on Characteristics of Stresses in U-Shaped Metal
Abstract: 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.
PubDate: Mon, 14 Sep 2015 11:30:25 +000
- Effect of Electrode Types on the Solidification Cracking Susceptibility of
Austenitic Stainless Steel Weld Metal
Abstract: 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.
PubDate: Wed, 12 Aug 2015 06:37:40 +000
- Microstructure, Strength, and Fracture Topography Relations in AISI 316L
Stainless Steel, as Seen through a Fractal Approach and the Hall-Petch Law
Abstract: 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.
PubDate: Mon, 27 Jul 2015 06:22:08 +000
- Response of Functionally Graded Material Plate under Thermomechanical Load
Subjected to Various Boundary Conditions
Abstract: 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.
PubDate: Sun, 15 Feb 2015 09:17:06 +000
- A Numerical Formula for General Prediction of Interface Bonding between
Alumina and Aluminum-Containing Alloys
Abstract: 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.
PubDate: Wed, 24 Dec 2014 08:53:16 +000
- Corrosion Behavior of Carbon Steel in Synthetically Produced Oil Field
Abstract: 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.
PubDate: Wed, 17 Dec 2014 06:04:32 +000
- Herbal Plant Synthesis of Antibacterial Silver Nanoparticles by Solanum
trilobatum and Its Characterization
Abstract: 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.
PubDate: Sun, 30 Nov 2014 00:10:03 +000
- Material Properties of Wire for the Fabrication of Knotted Fences
Abstract: 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.
PubDate: Wed, 26 Nov 2014 00:10:01 +000
- 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
Abstract: 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%.
PubDate: Thu, 13 Nov 2014 12:33:12 +000
- Modification of Magnesium Alloys by Ceramic Particles in Gravity Die
Abstract: 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.
PubDate: Thu, 30 Oct 2014 09:19:40 +000
- Thermodynamic Properties of LSCoO3
Abstract: 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).
PubDate: Mon, 29 Sep 2014 00:00:00 +000
- Accumulative Roll Bonding of Pure Copper and IF Steel
Abstract: 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.
PubDate: Tue, 23 Sep 2014 07:11:16 +000
- Static Response of Functionally Graded Material Plate under Transverse
Load for Varying Aspect Ratio
Abstract: 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.
PubDate: Mon, 30 Jun 2014 09:45:55 +000
- Band Gap Engineering of Alloys
Abstract: 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.
PubDate: Tue, 13 May 2014 11:14:46 +000
- Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique
for Optical Investigation
Abstract: 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.
PubDate: Mon, 14 Apr 2014 16:15:05 +000
- Synthesis and Characterization of Highly Efficient Nickel Nanocatalysts
and Their Use in Degradation of Organic Dyes
Abstract: 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).
PubDate: Thu, 27 Feb 2014 07:20:10 +000
- Algae Mediated Green Fabrication of Silver Nanoparticles and Examination
of Its Antifungal Activity against Clinical Pathogens
Abstract: 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.
PubDate: Sun, 19 Jan 2014 14:13:59 +000
- A Preliminary Study on Adhesion on Steel Cylinder Filled with Aluminum
Abstract: 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.
PubDate: Mon, 23 Dec 2013 09:28:07 +000
- Optimization of Conversion Treatment on Austenitic Stainless Steel Using
Abstract: 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.
PubDate: Wed, 18 Dec 2013 09:51:02 +000
- Nonlinear Optical Properties of Novel Mono-O-Hydroxy Bidentate Schiff
Base: Quantum Chemical Calculations
Abstract: 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.
PubDate: Tue, 17 Dec 2013 15:39:32 +000
- Optical Characteristics of Polystyrene Based Solid Polymer Composites:
Effect of Metallic Copper Powder
Abstract: 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.
PubDate: Thu, 12 Dec 2013 10:27:25 +000
- Spectroscopic Study of Al3+-Substituted Strontium Hexaferrite
Abstract: 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.
PubDate: Tue, 10 Dec 2013 11:03:41 +000