{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/53835"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/53835","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Understanding the Corrosion of Low-Voltage Al-Ga Anodes","abstract":"Aluminum is an attractive metal for use as an anode in the cathodic protection of steels in seawater due to its low cost and high current capacity. Zinc is often used for its ability to readily corrode, but it has a low current capacity and it operates at very negative voltages, leading to hydrogen generation at the steel cathode, which may cause hydrogen embrittlement. Aluminum can operate at less-negative voltages, therefore reducing hydrogen generation, but it forms a passive oxide film, preventing the anode from corroding. Ga is added to aluminum in small amounts (0.1 wt%) to destabilize this oxide film and allow for active corrosion. The mechanism of how Ga activates Al is still not well-known, though there are prevailing proposals. A previous study noted a difference in behavior between Al-Ga master heats and the alloys that were later produced by re-melting them. This study is focused on characterizing the corrosion behavior of Al-0.1 wt% Ga in synthetic seawater, with samples from a master heat and two subsequent remelts. Galvanostatic, potentiostatic, and open-circuit tests were run, as well as galvanic coupling with 1123 steel. It was found that the remelted anodes behaved more consistently and maintained stable corrosion behavior for longer times than the master heat. X-ray Photoelectron Spectroscopy analysis showed elevated concentrations of Ga inside the oxide layer. The findings support the mechanism in the literature of discrete particles of Ga forming under the oxide film but do not support the mechanism of an amalgam layer formation. This project was funded by NACE International, Virginia Tech project number 457789.","abstract_html":"Aluminum is an attractive metal for use as an anode in the cathodic protection of steels in seawater due to its low cost and high current capacity. Zinc is often used for its ability to readily corrode, but it has a low current capacity and it operates at very negative voltages, leading to hydrogen generation at the steel cathode, which may cause hydrogen embrittlement. Aluminum can operate at less-negative voltages, therefore reducing hydrogen generation, but it forms a passive oxide film, preventing the anode from corroding. Ga is added to aluminum in small amounts (0.1 wt%) to destabilize this oxide film and allow for active corrosion. The mechanism of how Ga activates Al is still not well-known, though there are prevailing proposals. A previous study noted a difference in behavior between Al-Ga master heats and the alloys that were later produced by re-melting them. This study is focused on characterizing the corrosion behavior of Al-0.1 wt% Ga in synthetic seawater, with samples from a master heat and two subsequent remelts. Galvanostatic, potentiostatic, and open-circuit tests were run, as well as galvanic coupling with 1123 steel. It was found that the remelted anodes behaved more consistently and maintained stable corrosion behavior for longer times than the master heat. X-ray Photoelectron Spectroscopy analysis showed elevated concentrations of Ga inside the oxide layer. The findings support the mechanism in the literature of discrete particles of Ga forming under the oxide film but do not support the mechanism of an amalgam layer formation. This project was funded by NACE International, Virginia Tech project number 457789.","abstract_has_math":false,"creators":["Baker, Devon Scott"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Materials Science and Engineering","degree_department":"Materials Science and Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Druschitz, Alan P."],"committee_members":["Corcoran, Sean G.","Reynolds, William T. Jr."],"year":2015,"date_issued":"2015-06-26","date_published":"2015-06-26","updated_at":"2026-07-22T22:19:26Z","subjects":["aluminum","gallium","anodes","seawater","corrosion"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:5178"],"render_values":[{"text":"vt_gsexam:5178","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/53835","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Druschitz, Alan P."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Corcoran, Sean G.","Reynolds, William T. 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Zinc is often used for its ability to readily corrode, but it has a low current capacity and it operates at very negative voltages, leading to hydrogen generation at the steel cathode, which may cause hydrogen embrittlement. Aluminum can operate at less-negative voltages, therefore reducing hydrogen generation, but it forms a passive oxide film, preventing the anode from corroding. Ga is added to aluminum in small amounts (0.1 wt%) to destabilize this oxide film and allow for active corrosion. The mechanism of how Ga activates Al is still not well-known, though there are prevailing proposals. A previous study noted a difference in behavior between Al-Ga master heats and the alloys that were later produced by re-melting them. This study is focused on characterizing the corrosion behavior of Al-0.1 wt% Ga in synthetic seawater, with samples from a master heat and two subsequent remelts. Galvanostatic, potentiostatic, and open-circuit tests were run, as well as galvanic coupling with 1123 steel. It was found that the remelted anodes behaved more consistently and maintained stable corrosion behavior for longer times than the master heat. X-ray Photoelectron Spectroscopy analysis showed elevated concentrations of Ga inside the oxide layer. The findings support the mechanism in the literature of discrete particles of Ga forming under the oxide film but do not support the mechanism of an amalgam layer formation. This project was funded by NACE International, Virginia Tech project number 457789."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Understanding the Corrosion of Low-Voltage Al-Ga Anodes"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Druschitz, Alan P."],"dc:contributor.committeemember":["Corcoran, Sean G.","Reynolds, William T. Jr."],"dc:contributor.department":["Materials Science and Engineering"],"dc:creator":["Baker, Devon Scott"],"dc:date.accessioned":["2015-06-27T08:00:54Z"],"dc:date.available":["2015-06-27T08:00:54Z"],"dc:date.issued":["2015-06-26"],"dc:description.abstract":["Aluminum is an attractive metal for use as an anode in the cathodic protection of steels in seawater due to its low cost and high current capacity. Zinc is often used for its ability to readily corrode, but it has a low current capacity and it operates at very negative voltages, leading to hydrogen generation at the steel cathode, which may cause hydrogen embrittlement. Aluminum can operate at less-negative voltages, therefore reducing hydrogen generation, but it forms a passive oxide film, preventing the anode from corroding. Ga is added to aluminum in small amounts (0.1 wt%) to destabilize this oxide film and allow for active corrosion. The mechanism of how Ga activates Al is still not well-known, though there are prevailing proposals. A previous study noted a difference in behavior between Al-Ga master heats and the alloys that were later produced by re-melting them. This study is focused on characterizing the corrosion behavior of Al-0.1 wt% Ga in synthetic seawater, with samples from a master heat and two subsequent remelts. Galvanostatic, potentiostatic, and open-circuit tests were run, as well as galvanic coupling with 1123 steel. It was found that the remelted anodes behaved more consistently and maintained stable corrosion behavior for longer times than the master heat. X-ray Photoelectron Spectroscopy analysis showed elevated concentrations of Ga inside the oxide layer. The findings support the mechanism in the literature of discrete particles of Ga forming under the oxide film but do not support the mechanism of an amalgam layer formation. This project was funded by NACE International, Virginia Tech project number 457789."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:5178"],"dc:identifier.uri":["http://hdl.handle.net/10919/53835"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["aluminum","gallium","anodes","seawater","corrosion"],"dc:title":["Understanding the Corrosion of Low-Voltage Al-Ga Anodes"],"dc:type":["Thesis"],"thesis:degree_discipline":["Materials Science and Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:26Z"}