• H N NARASIMHA MURTHY

      Articles written in Bulletin of Materials Science

    • Synthesis and characterization of spin-coated clay/PVDF thin films

      T S ROOPA H N NARASIMHA MURTHY H S SWATHI GANGADHAR ANGADI D V N HARISH

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      This paper reports the fabrication of Cloisite-15A (C-15A)-dispersed polyvinylidene fluoride (PVDF) nanocomposite thin films by spin coating and their characterization for sensor applications. The effects of nanoclay, duration ofultrasonication and spinning speed on the morphology and properties of thin films were studied. The influence of these parameters on the amount of β-phase was analysed using Fourier transform infrared (FTIR) and X-ray diffraction (XRD)techniques. The influence of C-15A on the morphology and surface quality of thin films was analysed by scanning electron microscopy (SEM). Piezoelectric coefficient was measured at 110 Hz and 0.25 N. Contact angle was measured to assess the hydrophobicity of thin films. The β-phase of 82.97% was obtained in the specimens with 5 wt% C-15A, processed at 500 rpm and spun for 35 min. The piezoelectricity of the specimens increased from $−$18 to $−$25 pC N$^{−1}$. Experiments were conducted as per L16 orthogonal array.

    • Joining of tubular steel–steel by unconventional magnetic pulse force: environmentally friendly technology

      K SHANTHALA T N SREENIVASA H N NARASIMHA MURTHY SHANTHARAM DOND HITESH CHOUDHURY ARCHANA SHARMA

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      Electromagnetic welding uses environment-friendly, unconventional non-contacting magnetic pulse force for joining of two metals. The present paper focuses on the welding of tubular mild steel to two different steel bars, ferrite-pearlite 1018 carbon steel and austenite 304 stainless steel using a 40 kJ electromagnetic instrument. A qualitative metallurgical bonding was obtained for a selected set of optimum process parameters. The bonded region did not show localized melting for a mild steel–carbon steel joint and was found to be homogeneous liquid state bonding for a mild steel–stainless steel joint within a restricted distance of 3 $\mu$m from the interface. Both the joints indicated good peel strength and leak tightness. Simulation studies were validated using experimental parameters such as voltage, current, impact velocity, magnetic fluxand displacement.

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