Galvanic Corrosion Behavior of Aluminum-Carbon Steel

Jamal M. Ali And Abbas K. Ibrahim, Dr.

	Galvanic Corrosion Behavior of Aluminum-Carbon Steel
Iraqi journal of mechanical and material engineering
Article 1, Volume 0, Issue 0, 2010, Pages 798-807
Author
Dr. Jamal M. Ali and Abbas K. Ibrahim
Abstract
The galvanic corrosion behavior for Aluminum (Al), Carbon steel metals in aerated 3.5% NaCl solution has been investigated under turbulent controlled flow conditions at different temperatures using a rotating cylindrical electrode unit. Corrosion potential, potentiostatic polarization and galvanic corrosion experiments were carried out at 313,323 and 333 k under rotational speed of 0, 50,125 and 200 r.p.m Potentiostatic polarization studies have been performed individually for Aluminum and Carbon steel and when they are coupled with an equal area (19.27 cm ), of cathode to anode. It was found the mass transfer process as measured by the limiting diffusion current density is not affected by the nature of the cathode material. For coupled metals, it is found that the corrosion process of Carbon steel and Al is under diffusion control since the corrosion rate increases with increasing rotational speed. The measured corrosion potentials of these metals give no exact information about the galvanic corrosion but only show the direction of current flow. The zero resistance ammeter has been used to measure the variation of galvanic current with time. The galvanic current was largely increased with increasing rotational speed (r.p.m.) and temperatures. The corrosion potential of (Al-Cs) coupled is larger than the corrosion potential of the individual anode member, which means large amount of anodic polarization due to this galvanic coupling. 2

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