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Optimization studies on thermal and mechanical manufacturing processes for multifilament superconducting tape and wireBasaran, Burak 15 November 2004 (has links)
There are many parameters that significantly affect the electrical performance of ceramic-core superconducting composite wire and tapes, which remain ambiguous and require more labor on their optimization. BSCCO 2212 has not been paid the attention and investment it deserves. In this regard, all optimization efforts were made for BSCCO 2223. In our work, a practical and inexpensive manufacturing method, thermally and mechanically optimized for Pb doped BiSrCaCuO 2212 superconducting multifilament (38 filaments) wires and tapes, was successfully employed. Optimized parameters can be classified under material, mechanical (deformation) and heat treatment (thermal) subgroups. Parameters involved with materials included investigation of deformation behavior of two different sheath metals; pure silver and 0.02% magnesia dispersion reinforced silver alloy. Pb doped BiSrCaCuO 2212 ceramic superconductor powder, the other source of material related parameters, was synthesized following the "Thermal Co-decomposition or Wet Mix" method. Fabrication of mono and multifilament wires with Oxide Powder in Tube (OPIT) method followed next. Optimization of drawing deformation was practiced to achieve the best ceramic grain alignment and smoother ceramic powder core/metal sheath interface in order to avoid "sausaging" in wires. Rolling of the wire products into tapes by following different deformation regimes was the other manufacturing stage of the project. Variable and constant reduction-per-pass deformation paths were employed to reveal their effects on our composites with distinct sheath material and filament formation. The search for the best (optimum) heat treatment schedule for our Bi2212 superconductor composites, a modified version of "step solidification partial melting", was employed successfully. A solution through tried recipes for the bubbling problem that occurred with our tapes was also addressed.
Electrical performance tests of fully reacted wires were carried out in our laboratory and very promising results were attained.
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Study of formation and convective transport of aerosols using optical diagnostic techniqueKim, Tae-Kyun 30 September 2004 (has links)
The characteristics of liquid and solid aerosols have been intensively investigated by means of optical diagnostic techniques. Part I describes the characteristics of liquid aerosol formation formed by heat transfer fluids (HTFs) from bulk liquids. Part II investigates the characteristics of convective transport behavior of solid particles in virtual impactor (VI). The objective of part I is to establish correlations which offer predictions on atomized particle size of HTFs which are widely and commonly used in process industries. There are numerous reports stating that mist explosions formed from leakage cause disastrous accidents in process industries. For safety concerns, the characteristics of mist formation should be known in order to prevent HTFs from catching on fire or exploding. The empirical data on formation of mist are collected by the optical measurement technique, the Fraunhofer diffraction. The Buckingham-PI theorem is applied to establish a correlation between empirical data and representative physical properties of HTFs. Final results of correlations are solved by a statistical method of linear regression. The objective of part II is to investigate the characteristics of convective transport behavior in virtual impactor (VI) which is used to sort polydisperse precursor powder in the process industries of superconductor wire. VI is the device to separate polydisperse particles as a function of particle size by using the difference in inertia between different sizes of particles. To optimize VI performance, the characteristics of convective transport should be identified. This objective is achieved by visualization techniques. The applied visualization techniques are Mie-scattering and laser induced fluorescence (LIF). To investigate analytically, a local Stokes number is introduced in order to offer criteria on predicting the efficiency of VI performance and boundary effect on particle separation. The achieved results can enhance performance and eliminate defects by having knowledge of the behavior of solid particles in VI.
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Study of formation and convective transport of aerosols using optical diagnostic techniqueKim, Tae-Kyun 30 September 2004 (has links)
The characteristics of liquid and solid aerosols have been intensively investigated by means of optical diagnostic techniques. Part I describes the characteristics of liquid aerosol formation formed by heat transfer fluids (HTFs) from bulk liquids. Part II investigates the characteristics of convective transport behavior of solid particles in virtual impactor (VI). The objective of part I is to establish correlations which offer predictions on atomized particle size of HTFs which are widely and commonly used in process industries. There are numerous reports stating that mist explosions formed from leakage cause disastrous accidents in process industries. For safety concerns, the characteristics of mist formation should be known in order to prevent HTFs from catching on fire or exploding. The empirical data on formation of mist are collected by the optical measurement technique, the Fraunhofer diffraction. The Buckingham-PI theorem is applied to establish a correlation between empirical data and representative physical properties of HTFs. Final results of correlations are solved by a statistical method of linear regression. The objective of part II is to investigate the characteristics of convective transport behavior in virtual impactor (VI) which is used to sort polydisperse precursor powder in the process industries of superconductor wire. VI is the device to separate polydisperse particles as a function of particle size by using the difference in inertia between different sizes of particles. To optimize VI performance, the characteristics of convective transport should be identified. This objective is achieved by visualization techniques. The applied visualization techniques are Mie-scattering and laser induced fluorescence (LIF). To investigate analytically, a local Stokes number is introduced in order to offer criteria on predicting the efficiency of VI performance and boundary effect on particle separation. The achieved results can enhance performance and eliminate defects by having knowledge of the behavior of solid particles in VI.
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