Studies on electro-chemical corrosion of carbon fiber reinforced aluminium alloy AA7075

• Published in: Sadhana (Bangalore) Vol. 44; no. 11; pp. 1 - 10
• Main Authors: Deshpande, Madhuri, Vagge, S T, Narayan Murty, S V S, Kale, Harishwar, Gondil, Ramesh
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01-11-2019; Springer Nature B.V
• Subjects: Aluminum base alloys; Carbon fiber reinforcement; Carbon fibers; Composite materials; Corrosion currents; Corrosion environments; Corrosion rate; Corrosion resistance; Corrosion resistant alloys; Corrosion tests; Electrolytic cells; Engineering; Fiber composites; Hot pressing; Organic chemistry; Photomicrographs; Thermodynamic properties; Carbon fibers; corrosion; AA7075 alloy; metal matrix composites; SEM/EDS
• ISSN: 0256-2499; 0973-7677
• DOI: 10.1007/s12046-019-1213-y

Carbon fiber reinforced AA7075 is known for good thermal properties and thus used as heat dissipating material. However, few such applications involve corrosive environments too, and hence there is a need to study the behavior of these composite materials under corrosive environment. In the present work, milled carbon fiber reinforced AA7075 composites were produced by vacuum hot pressing with varying amounts of milled carbon fibers. The relative densities of the composites were measured. SEM-EDS, TEM and XRD techniques were also employed for characterization. The composites were then characterized for electro-chemical behavior in 3.5 wt.% aqueous NaCl solution by electrochemical polarization technique. Results showed that the corrosion potentials E
corr
have shifted to more negative direction and thus showed increase in corrosion current density, leading to increase in corrosion rate with increasing vol.% of carbon fibers. These results were complemented by SEM micrographs of the composites after corrosion test, which revealed that corrosion occurred at the interface of carbon fiber and matrix due to formation of galvanic coupling between carbon fiber and matrix. Thus, reduced corrosion resistance in composites as amount of fibers increases, is attributed to increase in number of galvanic cells that form at the interface.