Electrochemical characterization and degradation of carbon fibre reinforced polymer in quiescent near neutral chloride media

In a quest for a better understanding of the mechanism and contribution(s) of fresh (“un-degraded”) and degraded CFRP surfaces to galvanic corrosion of coupled metals in multi-material assemblies the electrochemical behaviour of CFRP in quiescent 50 mM NaCl was studied using electrochemical techniques. Tests using ferricyanide/ferrocyanide redox couple revealed a quasi-reversible behaviour. Under cathodic polarization, CFRP is active electrochemically evidenced by the increase in pH (to pH ≥ 10). Galvanic current densities and potentials for Al-CFRP couple comprised of freshly polished CFRP sample ranged from 15–25 µA cm −2 and ≈−660 to −850 mV SCE respectively, while the corresponding parameter for Al-CFRP couple comprised of degraded CFRP were in the range 10–25 µA cm −2 and ≈−670 to −900 mV SCE . Contrary to expectations, CFRP prior exposure to degradative high pH media before galvanic coupling did not result in an increase in the intensity of galvanic corrosion of the coupled metal.