Faculty Publications
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Item Corrosion of aged and annealed 18 Ni 250 grade maraging steel in phosphoric acid medium(2010) Poornima, T.; Nayak, J.; Nityananda Shetty, A.N.The corrosion behavior of aged and annealed sample of 18 Ni 250 grade maraging steel was investigated in phosphoric acid over a range of acid concentration and solution temperature by using electrochemical techniques like Tafel extrapolation and electrochemical impedance spectroscopy. The studies have revealed that the corrosion rate of both aged and annealed samples increase with increase in temperature and increase in concentration of phosphoric acid in the medium. The corrosion rate of annealed sample is found to be less than that of aged sample. The thermodynamic parameters like activation energy, enthalpy of activation and entropy of activation for the corrosion process were calculated. © 2010 by ESG.Item Adsorption and inhibitor action of 4-(N,N-dimethylamino) benzaldehyde thiosemicarbazone on 6061 Al/SiC composite and its base alloy in sulfuric acid medium(2011) Geetha, G.M.; Nayak, J.; Nityananda Shetty, A.N.The inhibitive action of 4-(N,N-dimethylamino)benzaldehyde thiosemicarbazone (DMABT) on the corrosion behavior of 6061 Al -15 vol. pct. SiC(p) composite and its base alloy was studied at different temperatures in sulfuric acid medium containing varying concentrations of it, using Tafel extrapolation technique and AC impedance spectroscopy (EIS). Results showed that DMABT was an effective inhibitor, showing inhibition efficiency of 70% in 0.5 M sulfuric acid. The adsorption of DMABT on both the composite and base alloy was found to be through physisorption obeying Langmuir adsorption isotherm. The thermodynamic parameters such as free energy of adsorption and activation parameters were calculated. © Taylor & Francis Group, LLC.Item 3-Methyl-4-amino-5-mercapto-1,2,4-triazole as corrosion inhibitor for 6061/Al-15 (vol-%) sic(p) composite in 0.5M sodium hydroxide solution(2011) Kumari, P.D.R.; Nayak, J.; Nityananda Shetty, A.N.3-Methyl-4-amino-5-mercapto-1,2,4-triazole (MAMT) was investigated for its inhibition action on the corrosion of 6061/Al - 15 (vol-%) SiC(p) composite in 0.5M sodium hydroxide solution at different temperatures by potentiodynamic polarization and electrochemical impedance spectroscopic techniques. The effect of inhibitor concentration, temperature and concentration of the corrosion medium on the inhibitor action was investigated. The inhibition efficiency increased with the increase in the concentration of inhibitor but decreased with the increase in temperature. Both thermodynamic and activation parameters were calculated and discussed. The adsorption of MAMT on the composite was found to be through physisorption obeying Langmuir's adsorption isotherm.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 Influence of sulfate ion concentration and pH on the corrosion of Mg-Al-Zn-Mn (GA9) magnesium alloy(National Engg. Reaserch Center for Magnesium Alloys zhangdingfei@cqu.edu.cn, 2015) Shetty, S.; Nayak, J.; Nityananda Shetty, A.N.The corrosion behavior of Mg-Al-Zn-Mn (GA9) alloy in sodium sulfate solutions was studied over a range of concentrations and solution temperatures at different pH conditions by electrochemical techniques like Tafel extrapolation and electrochemical impedance spectroscopy (EIS). The studies were carried out in solutions with sodium sulfate concentrations 0.1M, 0.5M, 1M, 1.5M and 2M; and at five different temperatures of 30, 35, 40, 45 and 50 °C in a pH range of 3-12. As per the experimental data, the corrosion rate of the alloy increased with the increase in temperature, and also with the increase in concentration of sodium sulfate in the medium. It was observed that the rate of corrosion decreased with the increase in pH. The activation parameters like activation energy, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the alloy was examined before and after corrosion using scanning electron microscopy (SEM). © 2015.