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dc.contributor.authorKidd Jr, Michael Scotten_US
dc.date.accessioned2019-04-20T08:00:22Z
dc.date.available2019-04-20T08:00:22Z
dc.date.issued2019-04-19
dc.identifier.othervt_gsexam:19193en_US
dc.identifier.urihttp://hdl.handle.net/10919/89066
dc.description.abstractMarine structures must withstand the corrosive effects of salt water in a way that is low cost, reliable, and environmentally friendly. Aluminum satisfies these conditions, and would be a good choice for a sacrificial anode to protect steel structures if it did not passivate. However, various elements can be added to aluminum to prevent this passivation. Currently, Al-Ga alloys are used commercially as sacrificial anodes but their performance is not consistent. In this research, Thermo-Calc software was used to simulate various aspects of the Al-Ga system in an attempt to understand and potentially correct this reliability issue. Simulations showed that gallium segregates to the grain boundaries during solidification and then diffuses back into the grains during cooling to room temperature. Simulations also suggest that faster cooling rates and larger grains cause the potential segregation of gallium at the grain boundaries to remain after cooling. A set of aluminum plus 0.1% weight percent gallium alloy plates were produced with varying cooling rates, along with a control set (cooled slowly in a sand mold). Some samples were later homogenized via annealing. Samples were subjected to a 168 hour long galvanostatic test to assess voltage response. The corrosion performance of samples was found to have both consistent and optimal voltage range when subjected to quick cooling rates followed by annealing. Testing samples at near freezing temperature seems to completely remove optimal corrosion behavior, suggesting that there are multiple causes for the voltage behavior.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis item is protected by copyright and/or related rights. Some uses of this item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectCorrosionen_US
dc.subjectCathodic Protectionen_US
dc.subjectSacrificial Anodeen_US
dc.subjectAl-Gaen_US
dc.subjectGalvanostaticen_US
dc.subjectDiffusion Simulationen_US
dc.titleAl-Ga Sacrificial Anodes: Understanding Performance via Simulation and Modification of Alloy Segregationen_US
dc.typeThesisen_US
dc.contributor.departmentMaterials Science and Engineeringen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMaterials Science and Engineeringen_US
dc.contributor.committeechairDruschitz, Alan P.en_US
dc.contributor.committeememberReynolds, William T.en_US
dc.contributor.committeememberCorcoran, Sean G.en_US


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