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In the present investigation, long term service performance of silicone rubber based polymeric insulators under DC stress with controlled climatic conditions is attempted. Simultaneous application of UV, thermal, humidity with DC electrical stress is applied to polymeric insulators enclosed in a specially fabricated climatic chamber. The stresses are applied for 1000 h for an adopted cycle to simulate close service life conditions. The leakage current is regularly monitored and recorded. After the experimentation, samples of the aged specimen are subjected for post analysis and psycho-chemical analysis like Scanning Electron Microscope (SEM) to monitor morphological changes, Energy Dispersive X-Ray analysis (EDAX) to observe elemental presence over the surface, Fourier Transform Infra-Red (FTIR) spectroscopy to examine chemical changes in the material, Thermo-gravimetric analysis (TGA) to understand the role of filler in aged insulator specimen and loss of Loss of hydrophobicity was measured. Investigations with long duration DC stress reveal material degradation, depolymerization and loss of ATH; this could result in low thermal stability and accelerate the thermal erosion and early failures. [ABSTRACT FROM AUTHOR]

Pr3+ and Tm3+ (0.2 mol %) ions doped magnesium calcium bismuth titanate [(MgCa)2 Bi4Ti5O20] ceramics were synthesized by conventional solid state reaction method. The structural and morphological properties of prepared ceramic powders were studied by using XRD and SEM profiles. The elemental analysis and FTIR spectra of the prepared ceramics have been analyzed. Emission spectrum of Pr3+: (MgCa)2Bi4Ti5O20 ceramic powder has shown strong red emission at 614 nm (3P0 → 3H6) with an excitation wavelength λexci = 452 nm (3H4 → 3P2) and Tm3+: (MgCa)2Bi4Ti5O20 ceramic powder has shown blue emission at 477 nm (1G4 → 3H6) with an excitation wavelength λexci = 367 nm (3H6 → 1D2). [ABSTRACT FROM AUTHOR]

The nanoalumina particles were produced by the wire explosion process. The size and the shape of the particles were measured using Transmission Electron Microscope (TEM) studies. The Scanning Electron Microscope (SEM) studies were carried out to confirm that the particles are of sub-micron size. The compositions of the material were characterized through the Energy Dispersive Angle X-ray Analysis (EDAX) results. The Wide Angle X-ray Diffraction (WAXD) and the Fourier Transform Infra-Red (FTIR) results confirmed the nanosize powder formed by the process as crystalline γ-Al2O3 powder. The thermal characteristics were analyzed using Thermo-gravimetric Differential thermal analysis (TG-DTA). It is identified that the local temperature of the medium at the time of formation of nanopowder decides the phase characteristics of the powder material. The formation mechanism of nanopowder by wire explosion technique was explained in detail. The mechanism of nanopowder formation and the characteristic changes that occur during the explosion process were recorded using a high-speed digital camera. [ABSTRACT FROM AUTHOR]