Browsing by Subject "Silicon Carbide"
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Item Power Converter Design Options for the 12kVdc Bus System(2017-06-15) Gattozzi, A.L.; Strank, S.M.; Pish, S.P.; Hebner, R.E.; Engelkemeir, F.D.The US Navy’s recent reduction of the dc bus voltage for the new surface combatant, from the original 20 kV to the new target of 12 kV, opens up the design space to a broader range of options than was possible to date. This paper is an attempt to address the opportunities and risks associated with the adoption of multi-level topologies and Silicon-Carbide switches in the design of power converters for the new ships when compared with a more evolutionary innovative path offered by using soft-switching topologies with Silicon switch technology.Item Reaction Bonded Silicon Carbide: SFF, Process Refinement and Applications(2003) Evans, R. Scott; Bourell, David L.; Beaman, Joseph J.; Campbell, Matthew I.Reaction bonded silicon carbide (RBSiC) has a wide variety of industrial applications and a manufacturing process based on Selective Laser Sintering (SLS) has been demonstrated in previous research at the University of Texas. That study was directed toward semiconductor manufacturing applications and was based on prior indirect SLS methods. Several key research questions were addressed for three main manufacturing phases: preform SLS, binder burnout and reactive infiltration. The current research is focused on development of material systems and manufacturing capability and is directed toward a broader set of potential applications. Preform formation utilizes SiC powder of an appropriate average particle size mixed with a multicomponent binder. The preform or green part is then placed in a vacuum furnace to carbonize the binder. The details of the binder chemistry must support accurate SFF shapes and acceptable surface roughness, a strong green part and maintenance of the part shape during the first furnace operation. Finally, the physics and chemistry of the infiltration process, based on the microstructure of the initial green preform, determine the viability of the manufacturing process and the characteristics of the final composite material. The functionality of metal, polymer and ceramic matrix composites can support the growing SFF industry desire to move beyond functional prototyping and into manufacturing arenas. This project is being explored for more general application to matrix composite materials, especially highly functional systems tailored specifically for SLS. The goal is to establish the governing principles of binder function, carbonization and infiltration as well as to understand the interdependence of these phases in terms of manufacturing application. With this understanding new applications and special SLS composites can support the development of new products and a greater SFF manufacturing presence. This paper provides an introduction to the material, a look at basic rapid manufacturing trends, an overview of the previous work, a review of relevant RBSiC material science issues, and an outline of the current study.Item Silicon Carbide Growth Using Laser Chemical Vapor Deposition(2003) Mi, Jian; Gillespie, Josh; Johnson, Ryan W.; Bondi, Scott N.; Lackey, W. JackSilicon Carbide (SiC) has been grown from methyltrichlorosilane (MTS) and hydrogen using the Georgia Tech Laser Chemical Vapor Deposition (LCVD) system. A morphology study of LCVD-SiC fibers and lines was completed. Graphite and single crystal silicon were used as the substrates. In order to provide guidance to future growth of SiC, thermodynamic calculations for the C-H-Si-Cl system were performed using the SOLGASMIX-PV program.Item Silicon Carbide Preforms for Metal Infiltration by Selective Laser Sintering™ of Polymer Encapsulated Powders(1993) Vail, N.K.; Barlow, J.W.; Marcus, H.L.A polymer encapsulated silicon carbide system has been developed for use with Selective Laser Sintering. Extensive studies with this material have provided information pertaining to processing and material parameters which most affect the strengths and densities of resulting green parts. The important parameters considered were particle size distribution of the powders, laser scanning conditions, and laser beam diameter. Simple and complex shapes were easily produced with this material using optimized parameters. Green objects were infused with metal by Lanxide using their pressureless infiltration process to produce both metal matrix and ceramic matrix composites. (Key Words: Silicon Carbide, Encapsulation, Polymer, Selective Laser Sintering, Composites).