Utilization of hydrophobic coatings on insulative skirts to attenuate galvanic corrosion between mechanically-fastened aluminum alloy and carbon-fiber reinforced polymer-matrix composites
Year: 2016
Journal: Electrochem. Commun.
Authors: Srinivasan, R; Hihara, LH
This paper describes the effect of hydrophobic coatings on insulative skirts to attenuate galvanic corrosion between mechanically-fastened aluminum alloy and carbon-fiber reinforced polymer-matrix composites (CFR PMC). The utilization of hydrophobic coatings on the insulative skirt can help to attenuate galvanic corrosion by disrupting the formation of a continuous electrolyte film. Initially, Siloxel (TM)-coated insulating skirts of various lengths (0.64 cm, 127 cm, 2.54 cm, 10.16 cm, and 20.32 cm) were tested in a humidity chamber at 90% relative humidity (RH) and 30 degrees C. The galvanic couples were sprayed with salt solutions of various concentrations (i.e., 10, 100, 1000, 10,000, and 20,000 ppm of chlorides). Results from humidity-chamber experiments showed that the Siloxel (TM) coatings with a contact angle of 90 degrees generally reduced galvanic corrosion rates by three orders of magnitude for a given skirt length. When the skirt (coated with Siloxel (TM)), however, was at an optimal length of only 0.64 cm, the galvanic current decreased by approximately six orders of magnitude due to capillary effects that wicked electrolyte away from the edge of the skirt. Skirts with different types of coatings (i.e., Siloxel (TM), polyurethane, epoxy, and latex) of various levels of hydrophobicity were also studied to determine the effect of the coating contact angle on the galvanic current. (C) 2016 Elsevier B.V. All rights reserved.
