Faculty Publications
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Item 3-Methyl-4-amino-5-mercapto-1,2,4-triazole as corrosion inhibitor for 6061 Al alloy in 0.5 M sodium hydroxide solution(Springer New York LLC barbara.b.bertram@gsk.com, 2011) Kumari, P.D.R.; Nayak, J.; Nityananda Shetty, A.N.3-Methyl-4-amino-5-mercapto-1,2,4-triazole (MAMT) was synthesized, and its inhibition action on the corrosion of 6061 Al alloy in 0.5 M sodium hydroxide was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The effect of inhibitor concentration, temperature, and concentration of the corrosion medium on the inhibitor action was investigated. The surface morphology of the metal surface was investigated by scanning electron microscopy (SEM). The inhibition efficiency increased with the increase in the concentration of the inhibitor, but decreased with the increase in temperature. Both thermodynamic and kinetic parameters were calculated and discussed. The adsorption of MAMT on the base alloy was found to be through physisorption, obeying Langmuir's adsorption isotherm. The results obtained from both the techniques were in good agreement with each other. © 2011 ACA and OCCA.Item 3,4-Dimethoxybenzaldehydethiosemicarbazone as corrosion inhibitor for aged 18 Ni 250 grade maraging steel in 0.5 M sulfuric acid(2011) Poornima, T.; Nayak, J.; Nityananda Shetty, A.N.The corrosion inhibition of the aged 18 Ni 250 grade maraging steel in 0.5 M sulfuric acid by 3,4-dimethoxybenzaldehydethiosemicarbazone(DMBTSC) has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) techniques. The inhibition efficiency increased with the increase in inhibitor concentration and decreased with the increase in temperature. Polarization curves indicated mixed type inhibition behavior affecting both cathodic and anodic corrosion currents. The thermodynamic parameters of corrosion and adsorption processes were evaluated. The adsorption of DMBTSC on the aged maraging steel surface was found to obey the Langmuir adsorption isotherm model, and the calculated Gibb's free energy values confirm the spontaneous adsorption. The results obtained by the two techniques were in good agreement. © 2010 Springer Science+Business Media B.V.Item CORROSION BEHAVIOR OF 18% Ni M250 GRADE MARAGING STEEL UNDER WELD-AGED CONDITION IN SULFURIC ACID MEDIUM(2012) Sanatkumar, B.S.; Nayak, J.; Nityananda Shetty, A.N.The corrosion behavior of 18% Ni M250 grade maraging steel under weld-aged condition was investigated in sulfuric acid medium of different concentrations (0.1-2 M) at different temperatures (30°-60°C). Electrochemical measurements were carried out using the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The results showed an increase in the corrosion rate with the increases in temperature as well with increase in the concentration of the corrosion medium. The results obtained from the Tafel extrapolation technique and electrochemical impedance spectroscopy were in good agreement. Activation parameters were evaluated using the Arrhenius equation and transition state equation. The surface morphology of the corroded specimen was compared with that of the un-corroded sample by using scanning electron microscopy (SEM). © 2012 Copyright Taylor and Francis Group, LLC.Item Electrochemical investigation on the corrosion of 18%Ni M250 grade maraging steel under welded condition in sulfuric acid medium(2013) Kumar, P.; Nityananda Shetty, A.N.The corrosion behavior of welded maraging steel in sulfuric acid solutions has been studied over a range of acid concentrations and solution temperatures by electrochemical techniques such as Tafel extrapolation and electrochemical impedance spectroscopy. The studies have revealed that the corrosion rate of welded maraging steel increases with the increase in temperature and increase in concentration of sulfuric acid in the medium. The thermodynamic parameters such as activation energy, enthalpy of activation and entropy of activation for the corrosion process are calculated. The results obtained through the two techniques are in good agreement. The surface morphology and surface composition of the corroded samples have been examined by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis, respectively. © 2013 Allerton Press, Inc.Item Inhibition effect of adsorption layer of 1-phenyl-4-(4-nitrophenyl) thiosemicarbazide on the corrosion of 18 Ni 250-grade welded maraging steel in 1.0 M hydrochloric acid medium(Kluwer Academic Publishers, 2015) Kumar, P.; Nityananda Shetty, A.N.The thiosemicarbazide derivative, 1-phenyl-4-(4-nitrophenyl)thiosemicarbazide (PNPT), was synthesized and its inhibiting action on the corrosion of welded maraging steel in 1.0 M hydrochloric acid was investigated by electrochemical methods of potentiodynamic (Tafel) polarization and electrochemical impedance spectroscopy. The inhibitor, PNPT, acted essentially as a mixed-type inhibitor with predominant cathodic action. The inhibition efficiency increased with the increase in inhibitor concentration. An inhibition efficiency of about 86 % was exhibited at 30 °C, which decreased with the increase in the temperature. The adsorption of the inhibitor layer formed was through predominant physical adsorption process. © 2014 Springer Science+Business Media Dordrecht.Item Eco-friendly benzimidazolium based ionic liquid as a corrosion inhibitor for aluminum alloy composite in acidic media(Elsevier B.V., 2017) Kshama, S.; Nityananda Shetty, A.N.A novel, relatively inexpensive ionic liquid, 1.3-bis[2-(4-methoxyphenyl)-2-oxoethyl]-1H–benzimidazol-3-ium bromide (MOBB), was synthesized and characterized using FTIR, NMR, LC-MS and single crystal XRD (SCXRD) techniques. MOBB was evaluated for its corrosion inhibition properties on 6061 Al-15 vol% SiC (P) composite in 0.1 M HCl and 0.1 M H2SO4 media at different temperatures (30–50 °C) by electrochemical impedance spectroscopy and potentiodynamic polarization methods. The adsorption of MOBB on the composite was predominantly through chemisorption, obeying Langmuir adsorption isotherm. Inhibition efficiencies of 98.7% in HCl and 98.8% in H2SO4 were obtained, MOBB acting as a mixed type of inhibitor with predominant cathodic control. © 2016Item Electrochemical corrosion study of Mg-Al-Zn-Mn alloy in aqueous ethylene glycol containing chloride ions(Elsevier Editora Ltda, 2017) Medhashree, H.; Nityananda Shetty, A.N.Nowadays most of the automobiles use magnesium alloys in the components of the engine coolant systems. These engine coolants used are mainly composed of aqueous ethylene glycol along with some inhibitors. Generally the engine coolants are contaminated by environmental anions like chlorides, which would enhance the rate of corrosion of the alloys used in the coolant system. In the present study, the corrosion behavior of Mg-Al-Zn-Mn alloy in 30% (v/v) aqueous ethylene glycol containing chloride anions at neutral pH was investigated. Electrochemical techniques, such as potentiodynamic polarization method, cyclic polarization and electrochemical impedance spectroscopy (EIS) were used to study the corrosion behavior of Mg-Al-Zn-Mn alloy. The surface morphology, microstructure and surface composition of the alloy were studied by using the scanning electron microscopy (SEM), optical microscopy and energy dispersion X-ray (EDX) analysis, respectively. Electrochemical investigations show that the rate of corrosion increases with the increase in chloride ion concentration and also with the increase in medium temperature. © 2016 Brazilian Metallurgical, Materials and Mining Association.Item The corrosion behavior of AZ31 alloy in chloride and sulfate media – A comparative study through electrochemical investigations(National Engg. Reaserch Center for Magnesium Alloys zhangdingfei@cqu.edu.cn, 2019) Acharya, M.; Nityananda Shetty, A.N.The magnesium alloys are considered to be the best structural materials, because of their advantageous weight to strength ratio. But, the limitation in their real field applications lies on the fact that magnesium alloys are highly susceptible for corrosion. The corrosion behaviour of AZ31 alloy was investigated by electrochemical methods in sodium chloride and sodium sulphate of different concentrations at different temperatures. The corrosion rate was monitored by potentiodynamic polarization technique and electrochemical impedance spectroscopy method. The surface morphology and surface composition of the freshly polished surface of the alloy was compared with that of the corroded surface by recording their SEM images and EDS, respectively. The results showed that the corrosion rate of AZ31 alloy increased with the increase in the temperature of the medium and also with the increase in the salt concentration of the medium. The activation parameters for the corrosion process were calculated and interpreted. © 2019Item Synergistic inhibition effect of trisodium phosphate and sodium benzoate with sodium dodecyl benzene sulphonate on the corrosion of Mg-Al-Zn-Mn alloy in 30% ethylene glycol containing chloride ions(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Medhashree, H.; Nityananda Shetty, A.N.The enhanced efficiency of the sodium dodecyl benzene sulphonate (SDBS) by the addition of trisodium phosphate and sodium benzoate on the corrosion inhibition of Mg-Al-Zn-Mn alloy in aqueous ethylene glycol solution (30%) containing chloride ions was studied by potentiodynamic polarization technique and electrochemical impedance spectroscopy method. The combination of SDBS with trisodium phosphate and sodium benzoate resulted in synergistic effects on the inhibition efficiency. The inhibition efficiencies decreased with the increase in the medium temperature. The mixture of inhibitors acted predominantly as anodic types and the adsorption of the inhibitors on the surface of the alloy obeyed Langmuir adsorption isotherm. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.Item Stearate as a green corrosion inhibitor of magnesium alloy ZE41 in sulfate medium(Elsevier B.V., 2019) Dindodi, N.; Nityananda Shetty, A.N.The efficiency of stearate as a corrosion inhibitor for magnesium alloy ZE41 has been studied in sodium sulfate medium, employing electrochemical techniques like potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of polarization study imply that stearate functions as a mixed-type corrosion inhibitor with a predominant anodic control. The adsorption of stearate on alloy surface is found to obey the Langmuir adsorption isotherm. The proposed inhibition mechanism involved adsorption of stearate onto metal surface, followed by precipitation of magnesium stearate within the microdefects of Mg(OH)2 surface film which enhanced the barrier effect of an otherwise porous partially protective film. © 2014 The Authors