Blistering of Graphite/Polymer Composites Galvanically Coupled with Metals in Sea Water
RHODE ISLAND UNIV KINGSTON COLL OF ENGINEERING
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Carbon reinforced polymer composites are extensively used in aerospace and marine applications. Carbon fibers in carbon reinforced composites, being electrically conductive, form galvanic couples when they come into contact with most metals in the presence of an electrolyte. Carbon is a noble material and becomes a cathode in the galvanic couples with steel, aluminum, etc. The galvanic couple resulted in blistering of these composites whereas uncoupled samples did not show blisters even after exposure to electrolyte for two years. These blisters termed as galvanic blisters are filled with liquids with pH 14. Galvanic blisters initiate at the fibermatrix interface. During this research, several carbon composites with vinyl ester, polyester, epoxy matrices were found to blister galvanically. Experiments showed that while fiber surface treatments may aid this blistering, they do not play a necessary part in blister formation. Electrochemical studies indicated that oxygen reduction takes place on the carbon surface in carbon fiber composites. The current is found to be limited by diffusion of oxygen to the cathode site.
- Physical Chemistry
- Polymer Chemistry
- Laminates and Composite Materials
- Properties of Metals and Alloys