Journal Articles
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Item Corrosion behaviour of 6061 Al - 15vol. Pct. SiC composite and its base alloy in a mixture of 1:1 Hydrochloric and sulphuric acid medium(2009) Geetha, G.M.; Nayak, J.; Nityananda Shetty, A.N.Silicon carbide particulate - reinforced aluminum (SiCp-Al) composites possess a unique combination of high specific strength, high elastic modulus, good wear resistance and good thermal stability than the corresponding non-reinforced matrix alloy systems. These composites are potential structural material for aerospace and automotive applications. The corrosion characteristics of 6061 Al/SiCp composite and the base alloy were experimentally assessed. The corrosion test was carried out at different temperatures in 1:1 mixture of hydrochloric acid and sulphuric acid at a concentration range of 0.01 to 1N for each of the acid, as corrosion media using Tafel extrapolation technique and Electrochemical impedance spectroscopy (EIS). The results obtained from Tafel extrapolation technique and Electrochemical impedance spectroscopy were in good agreement. The results showed an increase in the corrosion rate with increases in temperature as well as the increase in the concentration of the corrosion media. The thermodynamic parameters like energy of activation were calculated using Arrhenius theory equation and, enthalpy of activation and entropy of activation were calculated using transition state theory equation. © 2009 by ESG.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.