8,244 research outputs found
Fast decay time of Eu3+-doped Phosphor for 3D display devices by plasmon resonant nanoparticles
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Development of Si-SiC hybrid structures for elevated temperature micro-turbomachinery
No full textThe design of the Massachusetts Institute of Technology (MIT) microengine is limited in part by the material capability of Si primarily due to the pronounced thermal-softening and strain-softening at temperatures higher than the brittle-to-ductile transition temperature (BDT), approximately 550/spl deg/C. In order to circumvent this limitation, it has been proposed to reinforce the Si with chemical vapor deposited (CVD) SiC in strategic locations to create a Si-SiC hybrid microengine turbine spool. Detailed design of Si-SiC hybrid structures for high temperature micro-turbomachinery, however, has been hampered by the lack of understanding of the mechanical behavior of Si and SiC hybrid structures at elevated temperatures and by the unavailability of accurate material properties data for both Si and SiC at the temperatures of interest. In this work, a series of initial thermomechanical FE analyzes have been performed to assess the advantage of the hybrid structures, and to provide structural design criteria and fabrication requirements. Then, the feasibility of the Si-SiC hybrid structures concept for elevated temperature micro-turbomachinery was verified based on more rigorous mechanical testing at high temperatures. Finally, the Si-SiC hybrid spool design was critically reevaluated with regard to creep using a Si constitutive model developed as a separate effort
Investigation of discharge phenomena in AC-PDPs with an auxiliary electrode using the Vt closed surface
No full textThe effect of social embeddedness to the information systems continuance: Context of e-government system implementing in rural area
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Electromagnetic wave shielding effectiveness of SWNT-coated, transparent, conducting panels
No full textResidual stress in thick low-pressure chemical-vapor deposited polycrystalline SiC coatings on Si substrates
No full textResidual stress in thick coatings of polycrystalline chemical-vapor deposited SiC on Si substrates is a key variable that must be controlled if SiC is to be used in microelectromechanical systems. Studies have been conducted to characterize the residual stress level as a function of deposition temperature, Si wafer and SiC coating thickness, and the ratios of methyltrichlorosilane to hydrogen and hydrogen chloride. Wafer curvature was used to monitor residual stress in combination with a laminated plate analysis. Compressive intrinsic (growth) stresses were measured with magnitudes in the range of 200–300 MPa; however, these can be balanced with the tensile stress due to the thermal-expansion mismatch to leave near-zero stress at room temperature. The magnitude of the compressive intrinsic stress is consistent with previously reported values of surface stress in combination with the competition between grain-boundary energy and elastic strain energ
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