Browsing by Author "Manojkumar, P."

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    Assessment of corrosion and scratch resistance of plasma electrolytic oxidation and hard anodized coatings fabricated on AA7075-T6
    (Transactions of the Indian Institute of Metals, 2021) Premchand, C.; Hariprasad, S.; Saikiran, A.; Lokeshkumar, E.; Manojkumar, P.; Ravisankar, B.; Venkataraman, B.; Rameshbabu, N.
    Surface modification of high-strength aluminium alloy 7075-T6 by plasma electrolytic oxidation (PEO) and type II hard anodization (HA) is presented in the current work. PEO-based ceramic oxide coatings were fabricated by employing an alternating current (AC) power source with a current density of 300 mA/cm2. The concentration effect of electrolytes on the alumina coatings was investigated and optimized comprehensively. Three separate aqueous electrolytes with 1:3, 1:1 and 3:1 proportions of sodium silicate (Na2SiO3) and potassium hydroxide (KOH) were utilized to evaluate optimum electrolyte concentration for obtaining desired AC-PEO coatings. X-ray diffraction (XRD) was utilized to investigate the phase composition of the coatings. Field emission scanning electron microscopy (FESEM) was employed to investigate the surface and cross-sectional characteristics of oxide coatings. Scratch testing was used to assess the oxide coatings’ adhesion ability, and potentiodynamic polarization (PDP) was utilized to assess the coatings’ corrosion behaviour in a 3.5 wt% aqueous NaCl solution. Among the AC-PEO and HA coatings, the AC-PEO specimen fabricated with equal ratios of sodium silicate and KOH concentration (Na2- SiO3:KOH 1:1) showed excellent adhesion strength (critical load, Lc = 41.5 N) along with the remarkable corrosion resistance (corrosion current density, icorr = 5.63 9 10–6 mA/cm2).
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    Facile preparation of immobilised visible light active W–TiO /rGOcomposite photocatalyst by plasma electrolytic oxidation process
    (Physica B: Condensed Matter, 2022-04) Manojkumar, P.; Lokeshkumar, E.; Premchand, C.; Saikiran, A.; Lingamaneni, Rama Krishna.; Rameshbabu, N.
    A highly efficient immobilised W–TiO/rGO composite photocatalyst was prepared as a coating on titaniumusing plasma electrolytic oxidation (PEO) with particle addition. The high dopant concentration in TiO resulted in smaller crystallite size , increased lattice strain, and dislocation density. The optimum Wcontaining G6W sample has improved electron mobility, higher charge carrier separation efficiency, andlower electron-hole recombination rate. This can be ascribed to the number of different defect centresemerging from tungsten interstitials and higher oxygen vacancies in the TiO structure. The catalystexhibited enhanced photocatalytic degradation efficiency (93%) of methylene blue dye than the pure TiO ,which was attributed to the synergetic effect of 2-D structured rGO and the changes incorporated upon tungsten interstitials in the TiO. The present research concludes that W–TiO/rGO photocatalyst by PEOprocess can be a good candidate for efficient, low cost, reusable, and visible-light-driven immobilisedphotocatalyst for textile wastewater treatment.