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    Assessment of corrosion behavior of ductile irons by factorial experiments
    (2009) Surendranathan, A.O.; Prabhu, K.N.; Sudhaker Nayak, H.V.
    The corrosion behavior of unalloyed and alloyed ductile irons (as cast, annealed, and cold worked) in sea water, dilute sulfuric acid, and dilute sodium hydroxide solutions was assessed. Specimen history had a significant effect on the corrosion potential except in ductile iron alloyed with Ni. When the specimens were subjected to different levels of cold working, the corrosion rate was influenced by both the history and the medium. Temperature had a significant effect on the corrosion rate except in the case of unalloyed ductile iron. Factorial experiments indicated that the cold-worked samples were more sensitive to the effect of temperature and composition on the corrosion rate as compared to annealed and as-cast samples. The medium had a significant effect on the corrosion rate in all the cases. © 2009 ASM International.
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    Liquid-liquid equilibrium of poly(ethylene glycol) 2000 + diammonium hydrogen citrate + water system at different temperatures
    (2011) Iyyaswami, I.; Srikanth, C.K.; Sindhu, N.
    Phase diagrams and liquid-liquid equilibrium (LLE) data of the aqueous poly(ethylene glycol) (PEG-2000) + diammonium hydrogen citrate system (aqueous two-phase system) has been determined experimentally at (298.15, 303.15, 308.15, 313.15, and 318.15) K. The effects of temperature on the binodal curve and tie-lines have been studied. The binodal curve was fitted to an empirical equation relating the concentrations of PEG 2000 and diammonium hydrogen citrate, and the coefficients were estimated for the respective temperatures. Tie line compositions were estimated and correlated using Othmer-Tobias and Bancroft equations, and the parameters are reported. The effect of temperature on the phase-forming ability in the investigated system has been studied based on a salting-out coefficient; obtained from fitting the binodal data to a Setschenow-type equation for each temperature. The effective excluded volume values were also calculated from the binodal data. © 2011 American Chemical Society.
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    Effect of temperature and substrate surface texture on wettability and morphology of IMCs between Sn-0.7Cu solder alloy and copper substrate
    (2012) Satyanarayan, S.; Prabhu, K.N.
    In the present work, the effect of soldering temperature (270 and 298 °C) and substrate surface texture (0.02 and 1.12 ?m) on wetting characteristics and morphology of intermetallic compounds (IMCs) between Sn-0.7Cu lead-free solder on copper substrates was investigated. It was found that increase in temperature and substrate surface roughness improved the wettability of solder alloy. However, the effect of surface roughness on wettability was significant as compared to that of temperature. The spreading of solder alloy was uniform on smooth substrate, whereas spreading of the alloy on rough substrate resulted in an oval shape. The morphology of IMCs transformed from long needle shaped to short and thick protrusions of IMCs with increase in surface roughness of the substrate. Needle shaped and thick protruded intermetallics formed at the solder/Cu interface were identified as Cu 6Sn 5 compounds. The formation of Cu 3Sn IMC was observed only for the spreading of solder alloy at 298 °C which contributed to improvement in the wettability of solder alloy on both smooth and rough substrate surfaces. © Springer Science+Business Media, LLC 2012.
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    Empirical potential influence and effect of temperature on the mechanical properties of pristine and defective hexagonal boron nitride
    (Institute of Physics Publishing helen.craven@iop.org, 2017) Thomas, S.; Ajith, K.M.; Valsakumar, M.C.
    The major objective of this work is to present results of a classical molecular dynamics study to investigate the effect of changing the cut-off distance in the empirical potential on the stress-strain relation and also the temperature dependent Young's modulus of pristine and defective hexagonal boron nitride. As the temperature increases, the computed Young's modulus shows a significant decrease along both the armchair and zigzag directions. The computed Young's modulus shows a trend in keeping with the structural anisotropy of h-BN. The variation of Young's modulus with system size is elucidated. The observed mechanical strength of h-BN is significantly affected by the vacancy and Stone-Wales type defects. The computed room temperature Young's modulus of pristine h-BN is 755 GPa and 769 GPa respectively along the armchair and zigzag directions. The decrease of Young's modulus with increase in temperature has been analyzed and the results show that the system with zigzag edge shows a higher value of Young's modulus in comparison to that with armchair edge. As the temperature increases, the computed stiffness decreases and the system with zigzag edge possesses a higher value of stiffness as compared to the armchair counterpart and this behaviour is consistent with the variation of Young's modulus. The defect analysis shows that presence of vacancy type defects leads to a higher Young's modulus, in the studied range with different percentage of defect concentration, in comparison with Stone-Wales defect. The variations in the peak position of the computed radial distribution function reveals the changes in the structural features of systems with zigzag and armchair edges in the presence of applied stress. © 2017 IOP Publishing Ltd.
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    Effect of temperature on magnetic and impedance properties of Fe3BO6 of nanotubular structure with a bonded B2O3 surface layer
    (American Institute of Physics Inc. subs@aip.org, 2018) Kumari, K.; Ram, S.; Kotnala, R.K.
    In this investigation, we explore a facile synthesis of Fe3BO6 in the form of small crystallites in the specific shape of nanotubes crystallized from a supercooled liquid Fe2O3-B2O3 precursor. This study includes high resolution transmission electron microscopy (HRTEM) images, magnetic, optical, and impedance properties of the sample. HRTEM images reveal small tubes of Fe3BO6 of 20 nm diameter. A well resolved hysteresis loop appears at 5 K in which the magnetization does not saturate even up to as high field as 50 kOe. It means that the Fe3BO6 nanotubes behave as highly antiferromagnetic in nature in which the surface spins do not align along the field so easily. The temperature dependent impedance describes an ionic Fe3BO6 conductor with a reasonably small activation energy Ea ? 0.33 eV. Impedance formalism in terms of a Cole-Cole plot shows a deviation from an ideal Debye-like behavior. We have also reported that electronic absorption spectra are over a spectral range 200-800 nm of wavelengths in order to find out how a bonded surface layer present on the Fe3BO6 crystallites tunes the 3d ? 3d electronic transitions in Fe3+ ions. © 2018 Author(s).
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    Active Vibration Control of Laminated Composite Beam Operating in Thermal Environment using PZT-5H Patches
    (Semnan University, Faculty of Mechanical Engineering, 2022) Saini, K.; Ravi Kiran, A.; Kallannavar, V.; Kattimani, S.
    This paper investigates the influence of temperature on the active vibration control of laminated composite cantilever beams using collocative experimental and simulation techniques. The system identification toolbox of the MATLAB simulation tool is utilized to obtain the transfer function of the plant model. The adequate vibration attenuation of the glass-epoxy cantilever beam operating in various thermal environments is achieved using the proportional (P) and proportional-integral-derivative (PID) controllers. The vibration attenuation characteristics of the developed control algorithms are comprehensively investigated for a wide temperature range of –20 °C to 60 °C using PZT-5H patches. Particular emphasis is given to the vibration control of the fundamental natural frequency of the laminated composite cantilever beam. The obtained results of open and closed-loop models are presented in both time and frequency domains. The results indicate that for all the temperatures considered, the PID controller is found to be more effective in vibration attenuation than the P controller. The vibration attenuation performance of the cantilever beam considerably improved at the higher magnitude of temperature values. The natural frequency of the system is reduced continuously with an increase in temperature. © 2022 Published by Semnan University Press. All rights reserved.