Due to the aluminum industry demands, a large effort has recently been devoted
to the development of special alloys to be used as inert anodes for a newly designed
aluminum reduction cell. The implementation of this new technology aims at the
replacement of the graphite anodes that have been used for over 100 years in aluminum
smelting, which would reduce fossil carbon consumption, and eliminate the emission of
carbon dioxide and of perfluorocarbons. Ternary alloys containing copper, nickel, and
iron have been the subject of the research activities.
The present research focused on the stability of the Cu-Ni-Fe alloys at high
temperatures in oxidizing and fluoridating environments. The experimental methods
included thermodynamic calculations of the phase diagram ('Thermocalc'), optical
microscopy and microprobe microstructural and chemical investigations (EMIPA-WDS),
small-angle neutron scattering (SANS), differential thermal analysis (DTA), and air-oxidation
studies.
The results have led to the optimization of the Cu-Ni-Fe ternary phase diagram
and to an extensive study of the thermodynamics and kinetics of the spinodal
decomposition and discontinuous reactions occurring during ageing as a function of alloy
composition.
The oxidizing reactions occurring in air at high temperatures at the surface of the
alloys have been also discussed in terms of thermodynamic and kinetic laws. The phase
formation in a fluorine containing environment as encountered in an aluminum
electrolytic cell is predicted using principles of physical chemistry. / Graduation date: 2004 / Best scan available. Figures in original document are very dark and have a moray pattern.
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29582 |
| Date | 25 November 2003 |
| Creators | Gallino, Isabella |
| Contributors | Kassner, Michael E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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