Browsing by Subject "electrical conductivity"
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Item Effect of Different Graphite Materials on Electrical Conductivity and Flexural Strength of Bipolar Plates Fabricated by Selective Laser Sintering(University of Texas at Austin, 2010-09-23) Guo, Nannan; Leu, Ming C.Graphite is an excellent material for bipolar plates used in Proton Exchange Membrane (PEM) fuel cell due to its great chemical resistance, but the brittle nature makes it difficult to manufacture. Selective Laser Sintering (SLS) based on layer-by-layer manufacturing technology can fabricate graphite bipolar plates with complex gas flow channels. To improve the performance of bipolar plates including electrical conductivity and flexural strength, different graphite materials (natural graphite, synthetic graphite, carbon black, and carbon fiber) were investigated to fabricate test samples. These samples then went through post processing including carbonization and infiltration. The results show that bipolar plates with electrical conductivity of 380 S/cm and flexural strength of 40 MPa are obtained from proper combinations of natural graphite and carbon fiber, which are higher than the target values set by the Department of Energy.Item Electrical Conductivity and Gamma Ray Response to Clay, Water, and Chloride Content in Fissured Sediments, Trans-Pecos, Texas(1995) Paine, Jeffrey G.; Goldsmith, Richard S.; Scanlon, Bridget R.Near-surface conductivity profiles determined using surface and borehole electromagnetic induction instruments were compared with each other and with variations in several important hydrological parameters, including clay content, water content, and chloride content in unsaturated sediments in fissured settings. Time-domain electromagnetic soundings were acquired at 10 boreholes in the Eagle Flat, Red Light Bolson, Hueco Bolson, and Ryan Flat areas in the arid Trans-Pecos region of West Texas. These boreholes were logged with induction and passive radiation probes to determine conductivity profiles and natural gamma ray activity. At the Red Light Bolson and Hueco Bolson fissures, the gamma logs were sensitive to clay content and followed the conventional trend of increasing count rates with increasing clay content. At Eagle Flat, gamma count rates were not much higher in the clay fraction than they were in the silt and sand fraction; thus, the gamma log underestimated the variability in clay content. At the Ryan Flat fissure, gamma count rates were higher than for the other fissure sites and were higher for the sand and silt fraction than for the clay fraction. This suggests that the sedimentary grains making up these deposits are volcanogenic and that the coarse fraction contains a larger percentage of K-bearing minerals than the clay fraction.Item Multifunctional Material Direct Printing for Laser Sintering Systems(University of Texas at Austin, 2013) Folgar, C.E.; Folgar, L.N.; Cormier, D.The research reports the development of advanced techniques for the direct print of materials into parts made by laser sintering. The present invention provides for the production of three-dimensional objects with improved build and support materials. The direct printed material may be metals, elastomers, ceramic, or any other material, which is typically different than the laser sintering material. Aspects of the technique include direct printed materials within laser sintered parts to improve part strength, provide multi-materials, provide electrical conductivity, and provide other desirable benefits to the part.Item Process and Properties of Carbon Black-Filled Electrically Conductive Nylon-12 Nanocomposites Produced by Selective Laser Sintering(University of Texas at Austin, 2009-09) Artreya, S.; Kalaitzidou, K.; Das, S.Electrically conductive polymer composites are suitable for use in the manufacture of antistatic products and components for electronic interconnects fuel cells and electromagnetic shielding. Selective laser sintering (SLS) was used to investigate the fabrication of electrically conductive nanocomposites of Nylon-12 filled with 4% by weight of carbon black. The effect of laser power and the scan speed on the flexural modulus and part density of the nanocomposite were studied. The set of parameters that yielded the maximum flexural modulus and part density was used to fabricate specimens to study the tensile, impact, rheological and viscoelastic properties. The electrical conductivity of the nanocomposite was investigated. The densities and the microstructures of the nanocomposites were studied using optical microscopy and scanning electron microscopy (SEM). The morphology of the nanocomposites was investigated using X-Ray diffraction (XRD) and differential scanning calorimetry.