• D SIVAKUMAR

      Articles written in Bulletin of Materials Science

    • Na-doped LiMnPO$_4$ as an electrode material for enhanced lithium ion batteries

      K RAJAMMAL D SIVAKUMAR NAVANEETHAN DURAISAMY K RAMESH S RAMESH

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      We report the influence of sodium (Na)-incorporated lithium manganese phosphate as an active material on its performance in electrochemical study for energy storage application. Li$_{1−x}$Na$_x$MnPO$_4$ with different mole ratios ($0.00 \le x \le 0.05$) of sodium is synthesized via a simple sol–gel method. The discharge capacity of Li$_{1−x}$Na$_x$MnPO$_4$ varies with respect to mole ratios of sodium incorporated. The maximum discharge capacityof 92.45 mAh g$^{−1}$ is observed in Li$_{0.97}$Na$_{0.03}$MnPO$_4$, which is higher than that of pristine LiMnPO$_4$ and other Na-incorporated LiMnPO$_4$. The maximum cyclic stability is found to be 84.15% up to 60 cycles. These results demonstrate that Li$_{0.97}$Na$_{0.03}$MnPO$_4$ plays a significant role in future energy storage application.

    • Characterization and optimization of influence of MoS$_2$ hybridization on tribological behaviours of Mg–B$_4$C composites

      C KAILASANATHAN P R RAJKUMAR N RAJINI G D SIVAKUMAR T RAMESH SIKIRU OLUWAROTIMI ISMAIL FARUQ MOHAMMAD HAMAD A AL-LOHEDAN

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      Aerospace and automobile industries are facing challenges in developing lightweight materials with high corrosion and wear resistance. The magnesium (Mg) alloys are superior to their monolithics, as they have maximum strength-to-weight ratio. These challenges can be solved with application of Mg-based hybrid composites. Therefore, this study investigated the hybridizing effect of molybdenum disulphide (MoS$_2$) reinforcement on tribological performance of magnesium–boron carbide (Mg–B$_4$C) hybrid composites, fabricated by powder metallurgy technique. Wear tests under dry sliding condition were carried out on the prepared composite samples with different proportions/weight percentage (wt%), using a pin-on-disc apparatus. Mg, MoS$_2$, B$_4$C and their various composites were characterized, using X-ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy analysis. The experiments were conducted using L$_{27}$ orthogonal array with five factors at three levels that affected the tribological performance. The wear resistance of the hybrid Mg–B$_4$C–MoS$_2$ composites significantly increased when compared with Mg–B$_4$C and Mg–MoS$_2$ composites, due to the refined effect of both reinforcements. Analysis of variance and grey-relational analysis result showed that increase in MoS$_2$, sliding distance ($D_{Sl}$) and load ($L_{Sl}$) significantly influenced the tribological performance of the hybrid composites. Mg–10wt%B$_4$C–5wt%MoS$_2$ exhibited significant best improvement on the multi-response tribological performance. The optimum quantity of MoS$_2$ reinforcement was around 7 wt%. Beyond this threshold proportion, wear was significantly increased, due to the agglomeration of MoS$_2$ particles. Hardness of the composites increased with hybridized reinforcements. SEM micrographs depicted the homogeneous dispersion of reinforcements in the Mg matrix. Also, SEM micrographs of the worn surfaces confirmed that delamination wear mechanism was dominant on the Mg hybrid composites.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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