Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Paul, C.P.Subject: search.filters.subject.Corrosion

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    Elucidating Corrosion Behavior of Hastelloy-X Built Using Laser Directed Energy Deposition-Based Additive Manufacturing in Acidic Environments
    (Springer Science and Business Media Deutschland GmbH, 2021) Diljith, P.K.; Jinoop, A.N.; Paul, C.P.; Krishna, P.; Bontha, S.; Bindra, K.S.
    This paper reports an investigation on the electrochemical corrosion behavior of laser directed energy deposition (LDED)-based additive manufacturing built Hastelloy-X (Hast-X) bulk samples for the first time in various acidic environments (2M HNO3, 2M HCl, and 2M H2SO4). Open-circuit potential results reveal that corrosion activity is more in HCl than the other two media. The corrosion rate (CR) estimated using the Tafel extrapolation method shows that the corrosion rate (CR) is the most in HCl and least in HNO3. Potentiodynamic studies reveal active–passive behavior of Hast-X in all the media and it is seen that the material stays in passivation for a longer potential range in HCl. Further, pitting potential is observed to be comparable in all three media. The cyclic polarization curve shows no loops, which points out the absence of pitting in the samples immersed in any of the media. The estimated CR for Hast-X in all the acidic environments under investigation comes within the acceptable CR for nickel-based alloys (4 mpy). The morphology of the corroded surface is analyzed using stereo microscope and it confirms the absence of pitting in all the three samples. These observations confirm the suitability of LDED built Hast-X components for applications in investigated acidic environments. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Understanding the corrosion behaviour of laser directed energy deposition-based additive manufacturing built Inconel 718 under acidic environments
    (Springer Science and Business Media Deutschland GmbH, 2021) Diljith, P.K.; Jinoop, A.N.; Paul, C.P.; Krishna, P.; Bontha, S.; Bindra, K.S.
    This paper presents an investigation on the electrochemical corrosion behaviour of Laser Directed Energy Deposition (LDED)-based additive manufacturing built Inconel 718 (IN718) for the first time in various acidic environments (2 M HNO3, 2 M HCl and 2 M H2SO4). Open circuit potential reveals that corrosion is more active in HCl, and Tafel extrapolation shows that the corrosion rate (CR) is maximum in HCl and minimum in HNO3. Potentiodynamic polarization studies conducted on the samples reveal active–passive behaviour of IN718 and show that pitting potential is maximum in HCl. Cyclic polarization studies reveal localized pitting behaviour in HCl, with no signs of pitting corrosion in HNO3 and H2SO4, which is further confirmed using Scanning Electron Microscopy. The estimated CR for IN718 is lower than the acceptable CR for nickel-based alloys (4 mpy) in all acidic environments under investigation. The study paves the way for potential deployment of LDED built IN718 components under various corrosive environments. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.