Browsing by Author "Latha, S."

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    Modelling the thermal creep behaviour of alloy D9 stainless steel clad tubes using theta projection method
    (2006) Mathew, M.D.; Latha, S.; Ramkumar, R.; Rao, K.B.S.; Mannan, S.L.
    Uniaxial creep rupture properties of alloy D9 stainless steel clad tubes have been evaluated at 923 and 973 K over a wide range of stress levels. The creep strain-time data (creep curve) have been analysed following the 4 Theta and 6 Theta parametric approaches. The stress dependencies of the Theta parameters were established and used to predict the creep curves. By applying strain to fracture as the failure criterion, the rupture lives were predicted at various test conditions. The creep curves of alloy D9 stainless steel could be modelled reasonably well using the 6 Theta approach whereas modeling using 4 Theta parameters was not satisfactory. The predicted rupture lives showed good agreement with the experimental data.
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    Modelling the thermal creep behaviour of alloy D9 stainless steel clad tubes using theta projection method
    (2006) Mathew, M.D.; Latha, S.; Ramkumar, R.; Bhanu Sankara Rao, K.B.S.; Mannan, S.L.
    Uniaxial creep rupture properties of alloy D9 stainless steel clad tubes have been evaluated at 923 and 973 K over a wide range of stress levels. The creep strain-time data (creep curve) have been analysed following the 4 Theta and 6 Theta parametric approaches. The stress dependencies of the Theta parameters were established and used to predict the creep curves. By applying strain to fracture as the failure criterion, the rupture lives were predicted at various test conditions. The creep curves of alloy D9 stainless steel could be modelled reasonably well using the 6 Theta approach whereas modeling using 4 Theta parameters was not satisfactory. The predicted rupture lives showed good agreement with the experimental data.
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    Optimization of process parameters to achieve spectrally selective TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO high temperature solar absorber coating
    (2016) Jyothi, J.; Latha, S.; Bera, P.; Nagaraja, H.S.; Barshilia, H.C.
    TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO tandem absorber was deposited on stainless steel substrate by using four cathode reactive direct current unbalanced magnetron sputtering system. The reactive gas flow rates (C2H2, N2 and O2) and thicknesses of each individual layers were varied to obtain the selective properties of the tandem absorber. The detailed effects of reactive gas flow rates and thicknesses of the individual layers on the optical properties were studied by using UV vis NIR spectrophotometer. Guiding factor in optimizing various process parameters was to achieve low reflectance in the solar spectrum region and high reflectance in the infrared region. The change in growth rate of the tandem absorber with reactive gas flow rate was studied using the thickness data, target voltage and target current. These results indicate a decrease in the growth rate of each individual layer of the tandem absorber with an increase in the flow rates of the reactive gases. The changes in bonding structure and chemical composition with reactive gas flow rates were studied by X-ray photoelectron spectroscopy. The optimized tandem absorber deposited on stainless steel substrate shows absorptance of 0.960 and emittance of 0.15. The thicknesses of the optimized individual layers were ?62, 18, 20, 16, 27 nm, respectively. 2016 Elsevier Ltd
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    Optimization of process parameters to achieve spectrally selective TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO high temperature solar absorber coating
    (Elsevier Ltd, 2016) Jyothi, J.; Latha, S.; Bera, P.; Nagaraja, H.S.; Barshilia, H.C.
    TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO tandem absorber was deposited on stainless steel substrate by using four cathode reactive direct current unbalanced magnetron sputtering system. The reactive gas flow rates (C2H2, N2 and O2) and thicknesses of each individual layers were varied to obtain the selective properties of the tandem absorber. The detailed effects of reactive gas flow rates and thicknesses of the individual layers on the optical properties were studied by using UV–vis–NIR spectrophotometer. Guiding factor in optimizing various process parameters was to achieve low reflectance in the solar spectrum region and high reflectance in the infrared region. The change in growth rate of the tandem absorber with reactive gas flow rate was studied using the thickness data, target voltage and target current. These results indicate a decrease in the growth rate of each individual layer of the tandem absorber with an increase in the flow rates of the reactive gases. The changes in bonding structure and chemical composition with reactive gas flow rates were studied by X-ray photoelectron spectroscopy. The optimized tandem absorber deposited on stainless steel substrate shows absorptance of 0.960 and emittance of 0.15. The thicknesses of the optimized individual layers were ?62, 18, 20, 16, 27 nm, respectively. © 2016 Elsevier Ltd