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dc.contributor.advisorPal, Uday B.en_US
dc.contributor.authorVillalon Jr., Thomas Anthonyen_US
dc.date.accessioned2018-08-09T15:43:17Z
dc.date.available2018-08-09T15:43:17Z
dc.date.issued2018
dc.identifier.urihttps://hdl.handle.net/2144/30729
dc.description.abstractCurrently, industrial processes that produce silicon occur in batch units which are energy intensive, capital intensive, and emit harmful pollutants into the atmosphere. A new technology, solid oxide membrane (SOM) processing, seeks to produce silicon without direct emissions and with lower energy and capital costs. Previous studies have shown that this technology can produce silicon; however, the proof-of- concept cell was incapable of producing large volumes of silicon due to restrictions in the molten salt. Current research has engineered an oxyfluoride molten salt to be more efficient in four main ways: higher amount of silica in the molten salt, chemistry stable with the yttria-stabilized zirconia (YSZ) membrane, low volatility, and high electrical conductivity. The newly designed salt allows for up to 25 at% of silicon oxide to dissolve into the flux, removing mass transfer limitations. The mixture utilizes calcium oxide to stabilize the presence of silicon oxide, giving the flux a volatility of less than 0.1 µg/cm 2 *s. The presence of calcium oxide also increases the optical basicity of the system, allowing the flux to be compatible with the YSZ membrane showing no signs of corrosion. Lastly, the new flux composition has a conductivity of 2.87 and 4.38 S/cm, at 1050 °C and 1100 °C, respectively, which is above the desired value of 1 S/cm. vii Combining these improvements in the salt with pre-existing techniques, silicon crystals were produced in the new SOM cell. Two distinct SOM cell configurations were attempted, one with a liquid cathode (tin) and one with a solid cathode (molybdenum). Both cells were able to successfully make silicon metal. The tin cathode was able to produce high purity silicon crystals extracted via acid etching. The molybdenum cathode produced a plated layer of molybdenum disilicide. Samples were examined by using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). An equivalent circuit model for the SOM process was developed to calculate polarization losses during the electrolysis process.en_US
dc.language.isoen_US
dc.subjectMetallurgyen_US
dc.subjectMaterials scienceen_US
dc.subjectSOM processen_US
dc.subjectYttria-stabilized zirconiaen_US
dc.titleZero-direct emission silicon production via solid oxide membrane electrolysisen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2018-07-03T01:04:44Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineMaterials Science & Engineeringen_US
etd.degree.grantorBoston Universityen_US


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