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The behaviour of homogeneous AlCu4 and AlZn3 in weakly acid and in O 2 ‐saturated chloride solutions
Author(s) -
Knörnschild G.,
Heldt J.,
Kaesche H.,
Mitterbacher H.
Publication year - 1995
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19950461003
Subject(s) - dissolution , alloy , chloride , homogeneous , electrolyte , electrochemistry , redox , inorganic chemistry , buffer solution , chemistry , aqueous solution , materials science , analytical chemistry (journal) , thermodynamics , electrode , metallurgy , chromatography , physics
The electrochemical behaviour of a homogeneous binary Al–4wt.%Cu and of a homogeneous binary Al–3wt.%Zn alloy in weakly acid chloride solutions, in O 2 ‐saturated chloride and citrate buffer solution and in Fe 2+ /Fe 3+ ‐containing citrate buffer solution has been examined using a rotating disc electrode. In weakly acid and in O 2 ‐containing solutions the behaviour of the AlCu and of the AlZn alloy differs from the behaviour of pure Al. H + ‐and O 2 ‐reduction at these alloys take place at a much higher rate. Under certain conditions, the reactions are even under transport control. Obviously, this is caused by the preceding selective dissolution of Al. Clusters from residual Cu and Zn, respectively, can pierce the passive layer and act as cathodic sites. In an electrolyte, where the passive layer is not dissolved, the AlZn and the AlCu alloy behave like pure Al. This is shown with the Fe 2+ /Fe 3+ redox system in a neutral buffer solution.