• R Sarathi

      Articles written in Bulletin of Materials Science

    • Investigation of surface modifications in ethylene propylene diene monomer (EPDM) rubber due to tracking under a.c. and d.c. voltages

      R Sarathi Uma Maheswar Rao

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      In the present work, tracking phenomena has been studied with the ethylene propylene diene monomer (EPDM) material under the a.c. and d.c. voltages, with ammonium chloride/acid rain solution as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), thermo-gravimetric differential thermal analysis (TG-DTA) and the differential scanning calorimetry (DSC) studies, were carried out and it was concluded that the tracking process is a surface degradation process. The tracking time is different for a.c. and d.c. voltages.

    • Investigations of surface characterization of silicone rubber due to tracking phenomena under a.c. and d.c. voltages

      Uma Maheswar Rao S S M S Abdul Majeed C Venkataseshaiah R Sarathi

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      In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric differential thermal analysis (TG–DTA) studies. The tracking time was different for a.c. and d.c. voltages.

    • Analysis of surface degradation of high density polyethylene (HDPE) insulation material due to tracking

      R Sarathi S Chandrasekar V Sabari Giri C Venkataseshaiah R Velmurugan

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      In the present work, tracking phenomena has been studied with HDPE material under a.c. voltage, with ammonium chloride as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The diffusion coefficient of the material was obtained. The thermal and chemical stability of the material were identified by carrying out a methodical experimental study. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), were carried out and it was concluded that the mechanism of tracking process is due to the surface degradation. The surface condition of the insulation structure was characterized for any surface discharges or tracking, using the leakage current measurement, utilizing the wavelet concepts.

    • Generation and characterization of nano aluminium powder obtained through wire explosion process

      T K Sindhu R Sarathi S R Chakravarthy

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      In the present study, nano aluminium particles were produced by wire explosion process (WEP) in nitrogen, argon and helium atmospheres. Thus produced nano particles were characterized through certain physico-chemical diagnostic studies using wide angle X-ray diffraction (WAXD) and by energy dispersive analysis by X-rays (EDAX). The size and shape of the powder were analysed by using transmission electron microscopic (TEM) studies. The particle size distribution studies were performed by adopting log-normal probability distribution. The relationship between size of the particle generated in the explosion process and the type of inert gas/pressure was analysed. The mechanisms of nano particle formation, the factors which can aid the process of formation of nano particle in the wire explosion process were analysed. It is realized that energy deposited to the conductor and duration of current flow have major impact on particles produced by this process.

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