Shanthi Jayachandran; Mohan Raman; Palanisamy Ponnusamy
Abstract
Wire Electrical Discharge Machining is one of the most effective Non-Conventional Machining method available to machine intricate shapes which are very difficult to machine with conventional machining methods, on electrically conductive materials havingvarying hardness. In this research work, an attempt ...
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Wire Electrical Discharge Machining is one of the most effective Non-Conventional Machining method available to machine intricate shapes which are very difficult to machine with conventional machining methods, on electrically conductive materials havingvarying hardness. In this research work, an attempt hasbeen made to study the effect of process parameters of WEDM on the Surface roughness. Input process parameters considered in this work are Pulse on time (TON), Pulse off time(TOFF), Wire Feed (WF), Wire Tension(WT) and theSurface Roughness as response. Al 7075 Aluminium alloywas taken as work material and Brass coated copper wire as electrode to machine and the values of roughness obtained by varying the input process parameters were analysed using Taguchi method (L 27 orthogonal array). The measured values have been used to develop the mathematical modeland the accuracy of the model wastested using Analysis of Variance (ANOVA) technique. Based on the predicted values the interaction graphs, were drawn betweentheSurface roughnessandthe processparameterstaken for this study. It was construedthatthepulse-on time has the highest impact on the Surface roughness followed by the Wire feed, Wire tension and the Pulse-off time. The surface roughnessgot increasedwith increase in wire feed. Finally optimum parameters have been arrived to achieve better surface roughness. WEDMed surface was also examined by using scanning electron microscope (SEM) and evinced that the physical behaviour of these process parameters on Surface roughness.Copyright © VBRI Press.
P Swapna; S Venkatramana Reddy
Abstract
Pure and (Ni, Al) co-doped ZnO nanostructures are prepared lucratively by chemical co-precipitation process at room temperature by means of poly ethylene glycol (PEG) as stabilizing agent. Zinc acetate dehydrate and potassium hydroxide are used as preliminary materials. The synthesized samples are characterized ...
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Pure and (Ni, Al) co-doped ZnO nanostructures are prepared lucratively by chemical co-precipitation process at room temperature by means of poly ethylene glycol (PEG) as stabilizing agent. Zinc acetate dehydrate and potassium hydroxide are used as preliminary materials. The synthesized samples are characterized by XRD, Scanning Electron Microscopy (SEM) with EDS, Photoluminescence (PL), and Transmission Electron Microscopy (TEM). X-RAY Diffraction pattern reveals that both pristine and co-doped samples acquire hexagonal wurtzite crystal structure with no secondary phase and nonappearance of secondary phase indicates the nonexistence of impurities. SEM descriptions illustrate that all the particles are almost spherical shape and EDAX analysis reveals that doing well incorporation of dopants and lack of impurities. PL spectrum shows that all the samples containing peaks in the visible region, which will be defect related peaks. Doped samples show high intensity peaks compared with the undoped sample. TEM images reveals the nature of the particles as spherical and size of nanoparticles are confirmed the XRD data. HRTEM images plainly be evidence for nanoparticles are about 5nm with unambiguous lattice fringes. Copyright © 2018 VBRI Press.
Himanshu Bisaria; Pragya Shandilya
Abstract
Ni-rich NiTi shape memory alloys (SMAs) are gaining more prominence compared to near equiatomic NiTi SMAs due to their excellent superelasticity and shape memory properties. The low density and high work output compared to steels make them an excellent choice for automotive and aerospace industries. ...
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Ni-rich NiTi shape memory alloys (SMAs) are gaining more prominence compared to near equiatomic NiTi SMAs due to their excellent superelasticity and shape memory properties. The low density and high work output compared to steels make them an excellent choice for automotive and aerospace industries. The study explores the effect of machining parameters, namely, pulse off time, pulse on time, spark gap voltage, wire tension and wire feed rate on material removal rate (MRR), surface roughness (Ra), and surface morphology of Ni-rich NiTi SMA. The experimental results reveal that MRR & Ra increase with the increase in pulse on time while decrease with the increase in pulse off time and spark gap voltage. Wire feed rate and wire tension have negligible influence on MRR and SR. Surface defects, namely, recast layer, micro-cracks & voids were examined through scanning electron microscope (SEM). Energy dispersive X-ray (EDS) and X-ray diffraction (XRD) analysis results reveal the material transfer from wire electrode and the dielectric fluid on the machined surface. Copyright © 2018 VBRI Press.
M.K. Debanath; R.K. Saha; S.M. Borah; E. Saikia; K.K. Saikia
Abstract
In our present investigation, we have synthesized starch-capped Cu doped ZnO (ZnO:Cu) nanoparticles (NPs) by simple wet chemical method and studied their structural, optical and antibacterial effects on/against Gram-positive and Gram-negative bacteria. Chemically synthesized nanoparticle have been characterized ...
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In our present investigation, we have synthesized starch-capped Cu doped ZnO (ZnO:Cu) nanoparticles (NPs) by simple wet chemical method and studied their structural, optical and antibacterial effects on/against Gram-positive and Gram-negative bacteria. Chemically synthesized nanoparticle have been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive analysis of X-rays (EDAX), high resolution transmission electron microscopy (HRTEM), UV-vis absorption spectroscopy and photoluminescence (PL) spectroscopy for their structural and optical properties. Antibacterial properties have been studied by Staphylococcus aureus (S. aureus, Gram-positive) and Escherichia coli (E. coli, Gram-negative) bacteria. XRD study showed hexagonal wurtzite crystal structure of the prepared ZnO:Cu and nanoformation of the as-synthesized NPs. Nanoparticle formation have been finally confirmed by HRTEM analysis. Antibacterial studies showed excellent resistance of ZnO:Cu to S. aureus and E. coli respectively. Copyright © 2018 VBRI Press.
Rajnish Kumar; S. A. R. Hashmi; Subhash Nimanpure; Ajay Naik
Abstract
Randomly distributed kenaf fibre with varying length (5-50mm) and weight fractions (25-40%) were used to reinforce epoxy resin to prepare environment friendly composites. Effect of fibre length with constant fibre loading on dynamic mechanical properties was studied and its effect on storage modulus, ...
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Randomly distributed kenaf fibre with varying length (5-50mm) and weight fractions (25-40%) were used to reinforce epoxy resin to prepare environment friendly composites. Effect of fibre length with constant fibre loading on dynamic mechanical properties was studied and its effect on storage modulus, loss modulus and damping factor were investigated. Kenaf fibres were also subjected to alkali treatment to improve interaction with the epoxy resin. The mechanical properties of composites improved with the length and loading of fibres. Tensile strength, flexural strength and impact strength of composites at 40 wt% of fibre reinforcement improved by 46, 51 and 97% as compared to the composites containing 25 wt% of kenaf fibre. It was also observed that fibre folds developed during mixing became significant factor which limited the improvement in mechanical strength of kenaf epoxy composites. A few important predictive models namely rule of mixture, Haplin-Tsai, Nielson Chen and Manera models were compared with the experimental values obtained in this present study. Manera model predicted the experimental data most accurately. Alkali treatment improved the interface and its outcome reflected in the improved modulus that increased 21.76% in samples having 10mm length of kenaf fibre. Copyright © 2017 VBRI Press.
Swati Tapdiya; Ashwani K. Shrivastava; Sarika Singh
Abstract
Manganese substituted Cobalt Ferrite Co1-xMnxFe2O4() nanoparticles were prepared using low temperature chemical co-precipitation method. All the samples were annealed at 900°C for 3 hours. The crystal lattice symmetry and phase purity were performed by X-ray diffraction (XRD). The varying dopent ...
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Manganese substituted Cobalt Ferrite Co1-xMnxFe2O4() nanoparticles were prepared using low temperature chemical co-precipitation method. All the samples were annealed at 900°C for 3 hours. The crystal lattice symmetry and phase purity were performed by X-ray diffraction (XRD). The varying dopent concentration affects the crystalline size, surface morphology and magnetic properties of the cobalt ferrite. The particle sizes are found to be in the range of 29-37 nm. SEM with EDAX examines the morphological and compositional analysis of the nanoparticles. EDAX confirms the presence of Co, Mn, Fe and O. Fourier transform infrared spectroscopy (FTIR) study confirms the formation of spinel ferrite. The saturation magnetization, magnetic remanence and coercive field of CoMn nanoparticles are obtained at room temperature. Saturation magnetization initially increases and then decreases for higher value of dopent, which shows applicability of these materials for recording media and magnetic data storage. Copyright © 2017 VBRI Press.
Nandeibam Nilima; Mamata Maisnam; Sumitra Phanjoubam
Abstract
Li-Ni-Co ferrite/SiO2 composites with representative formula Li0.41Ni0.1Co0.08Fe2.41O4+ xSiO2 (i.e., x = 0wt. %, 5wt. %,10wt. % and 20wt. %) were prepared by sol-gel method. The prepared composites were pre-sintered at 600ºC for 2 hrs and then finally sintered at 1000ºC for 6 hrs. X-ray diffraction ...
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Li-Ni-Co ferrite/SiO2 composites with representative formula Li0.41Ni0.1Co0.08Fe2.41O4+ xSiO2 (i.e., x = 0wt. %, 5wt. %,10wt. % and 20wt. %) were prepared by sol-gel method. The prepared composites were pre-sintered at 600ºC for 2 hrs and then finally sintered at 1000ºC for 6 hrs. X-ray diffraction studies showed diffraction peaks indicating single phase with spinel structure. However, peaks of SiO2 were found in composites of higher (x). The microstructure of the samples was studied by using Scanning Electron Microscopy. The crystallite size and average grain size were found to decrease with increase of SiO2 content. The room temperature frequency variation of dielectric constant and dielectric loss was measured from 100Hz-1MHz and they showed a dispersive behavior. The variation has been explained by Verwey mechanism of electron hopping and Koop’s two-layer model. The addition of SiO2 plays significant role in influencing the various structural, microstructural and electrical properties. Uniform and refined microstructures are observed with the addition of SiO2 and this reduces the value of dielectric constant and loss significantly, which is desirable for high frequency applications. The results obtained and mechanisms involved are discussed. Copyright © 2017 VBRI Press.
Sunita Khangembam; Maisnam Victory; Waikhom Surchandra; Sumitra Phanjoubam
Abstract
Recent technological breakthroughs and the desire for new functions generate an enormous demand for synthesizing new materials through different ways and methods which show superior properties compared with their pure counterparts. Presently, polycrystalline zinc doped nickel ferrites having the compositional ...
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Recent technological breakthroughs and the desire for new functions generate an enormous demand for synthesizing new materials through different ways and methods which show superior properties compared with their pure counterparts. Presently, polycrystalline zinc doped nickel ferrites having the compositional formula Ni1-xZnxFe2O4 where x = 0.0, 0.1, 0.2 and 0.4 were synthesized. Sol-gel auto combustion method was adopted for the preparation of these ferrites since it provides a simple and economic alternative technique ensuring good stoichiometric control, production of particles with narrow size distribution in a relatively shorter time, good homogeneity and high sinterability at lower temperature. Structural studies were carried out by XRD. Various structural properties like lattice parameter, crystallite size and density were calculated from the XRD data. Micro structural studies were carried out using Scanning Electron Microscopy (SEM), while the elemental compositions of all the samples were studied by Energy Dispersive X-ray Analysis (EDAX). The frequency variation of room temperature dielectric constant and dielectric loss was studied in the frequency range 100Hz – 1MHz and dispersive behavior was observed. The room temperature dc resistivity of all the samples was also investigated. Zn substituted nickel ferrites are found to be useful in microwave and electronic devices. Copyright © 2017 VBRI Press.
Elangbam C. Devi; Ibetombi Soibam
Abstract
Manganese ferrite nanoparticles with chemical formula MnFe2O4 have been synthesized by low temperature chemical co-precipitation method. The structural and optical properties of the nanoparticles were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray ...
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Manganese ferrite nanoparticles with chemical formula MnFe2O4 have been synthesized by low temperature chemical co-precipitation method. The structural and optical properties of the nanoparticles were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), fourier transform infra-red spectroscopy (FTIR) and UV-visible absorption spectroscopy. XRD confirm pure spinel phase formation of the prepared sample. All the observed peaks correspond to the standard diffraction pattern of manganese ferrite having JCPDS card number 74-2403. From the XRD data, the average crystallite size was calculated and found to be 27.40 nm. The FTIR spectrum shows the characteristic bands of the spinel ferrite. Morphology of the nanoferrites was given by SEM image revealing that the particles are approximately spherical in shape. The elemental composition along with their relative ratios was given by EDAX and was found to be in agreement with their initial calculated values. UV- visible absorption spectrum of the prepared sample shows characteristic absorption in visible range and from the UV-visible absorption data the band gap of the prepared sample was determined. MnFe2O4 nanoparticles were found to possess a narrow band gap of 1.4 eV which may find applications in photocatalytic degradation of pollutants. The simple co-precipitation method proves to be an effective method for synthesis of pure phase manganese ferrite nanoparticles. Copyright © 2017 VBRI Press.
M. Kanakadurga; S. R. Murthy; Arya Das; Rakesh K. Sahoo; Saroj K. Singh
Abstract
ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated ...
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ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated the presence of Zn, O, Na and Cl which confirms the presence of ZnO as major and NaCl as the minor phase. The precipitation of this minor phase after growth and catalytic induction in nano-platelet (NP) morphology during growth has been elucidated. The electrochemical performance of this as-synthesized powder is quite promising. Additionally, the effect of this minor NaCl phase in changing the ionic equilibrium of the electrolyte in capacitance measurement has been analyzed.
