Electrochemical and Quantum Chemical Studies of 5-[(4-Chlorophenoxy) Methyl]-4 H -1,2,4-Triazole-3-Thiol on the Corrosio
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TECHNICAL ARTICLE—PEER-REVIEWED
Electrochemical and Quantum Chemical Studies of 5-[(4-Chlorophenoxy) Methyl]-4H-1,2,4-Triazole-3-Thiol on the Corrosion Inhibition of 6061 Al Alloy in Hydrochloric Acid K. Raviprabha . Ramesh S. Bhat
Submitted: 15 February 2020 / Accepted: 13 July 2020 Ó ASM International 2020
Abstract Corrosion inhibition studies of 5-[(4chlorophenoxy) methyl]-4H-1, 2, 4-triazole-3-thiol (CMTT) on 6061 Al alloy in 0.05 M HCl were carried out at different concentrations and temperatures. Weight loss method, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed in the study. Higher concentration and temperature were found to improve the efficiency of inhibitor. Highest corrosion resistance of 95.29% was recorded with 100 ppm CMTT at 333 K. Adsorption of the inhibitor was spontaneous as indicated by Langmuir adsorption isotherm. Thermodynamic parameters, SEM, AFM results indicated that inhibitor used protects the alloy from corrosion. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (DE), dipole moment (l) and Mulliken charges are calculated. Quantum chemical calculations also endorsed experimental information and the adsorption of inhibitor molecules onto the metal surface. Keywords Corrosion Inhibitor 6061Al alloy HCl SEM AFM
K. Raviprabha R. S. Bhat (&) Department of Chemistry, Shri Madhwa Vadiraja Institute of Technology and Management, Bantakal, India e-mail: [email protected] R. S. Bhat Department of Chemistry, NMAM Institute of Technology, (Visvesvaraya Technological University, Belagavi), Nitte 574110, Karnataka, India
Introduction Aluminum has a special advantage of being lighter in its multifarious industrial applications coupled with a fairly strong negative standard reduction potential [1]. Aluminum and its alloys are used in industries due to economic recyclability and outstanding mechanical and physical characteristics such as low density, string heat conductive characteristics and good solderability [2]. Due to relative excellent resilience to corrosion, formability and low price, 6061 Al alloys are widely used in the aerospace, household, electric, automotive, marine and other construction sectors [3]. The most important feature of aluminum is its corrosion resistance due to the existence of a thin adherent and protective surface oxide film. Notwithstanding this favorable factor, the alloy is susceptible to corrosion [4, 5], especially under industrial acid cleaning, acid pickling, electrochemical and chemical grafting [6, 7].Though proper design and use of anodic and cathodic protection can go a long way in controlling corrosion, the use of organic heterocyclic compounds as inhibitors is a much desired alternative. Many numbers of literatures abound in the use of various organic compounds with a primary elemental composition of oxygen, sulfur and phosphorous in their structure along with unsaturated bonds or aromatic rings [8,
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