Date of Award
Maciej Kumosa, Ph.D.
Carbon fiber composite, Galvanic corrosion, High voltage, Power transmission line
Aluminum/carbon composite systems can have outstanding mechanical properties. Aluminum and carbon fiber reinforced polymer matrix composites (CFRP) are typically considered corrosion resistant when used alone, but can develop severe galvanic corrosion when in physical contact in the same component or structure.
General engineering practice is to avoid contact between aluminum and CFRP in any application where moisture may be present, but it is still of great importance to understand the consequences if the two materials accidentally become in contact. There may also be applications where a low rate of galvanic corrosion is acceptable.
This dissertation contributes unique experimental and numerical approaches to improve the fundamental understanding of galvanic corrosion in aluminum/carbon composite systems, with particular focus on rate limiting control mechanisms in a high-temperature low-sag bare overhead transmission line conductor utilizing a CFRP load bearing core.
The improved understanding was accomplished partially by the development of a novel assessment method for the in-situ galvanic corrosion testing of bare overhead conductors of various designs. The method allows for real-time measurements of galvanic corrosion currents while retaining the original geometry of the conductors.
One of the most important findings is that the galvanic corrosion is under cathodic control, which means that the total galvanic corrosion rate is determined by the exposed carbon area, and independent of the exposed aluminum area. Another important finding is that the galvanic corrosion process is under diffusion control, which means that the total galvanic corrosion rate is mainly controlled by the rate at which oxygen arrives at the carbon surface. The implication of these findings is that the geometry of the component or structure can affect the galvanic corrosion rate by orders of magnitude.
The dissertation work has also included the development of a structural health monitoring method for CFRP supported overhead conductors using Time Domain Reflectometry (TDR).
This comprehensive research has significantly contributed to the increased acceptance of CFRP supported bare overhead conductors in both the United States and worldwide. The knowledge gained in this study is already aiding the evaluation of existing conductor designs and the development of future ones.
Hakansson, Eva, "Galvanic Corrosion of Aluminum/Carbon Composite Systems" (2016). Electronic Theses and Dissertations. 1120.
Received from ProQuest