Corrosion behaviour of the AlSi6Cu4 alloy and cast AlSi6Cu4-graphite particles composite
Journal Title: Archiwum Odlewnictwa - Year 2009, Vol 9, Issue 2
Abstract
The corrosion behaviour of the AlSi6Cu4 alloy as a composite matrix and of composites with 8% vol. of graphite particles was investigated. The corrosion experiments were performed over a range of elevated temperatures and were carried out in sea water (3.5% NaCl solution). We have focused our attention to the determination of the mode of corrosion attack and to the determination of the rate of corrosion and other corrosion characteristics. Both as-cast and annealed matrix and composite specimens were tested, as well as the 99.9% as-cast aluminium for comparison. Corrosion behaviour of the materials was assessed by the corrosion potential (Ec) and by potentiodynamic (polarization) curves. As expected, composite is less corrosion resistant than the matrix alloy. In addition to pitting, a severe galvanic corrosion occurs as a result of galvanic couple aluminium/graphite formation. Corrosion potentials imply that examined materials would be sufficiently resistant in non or slightly oxidizing solutions without dissolved oxygen. All studied materials corrode very slowly at potentials negative to corrosion potential, while at potentials positive to corrosion potential the corrosion rate goes up by 1 or 2 orders.
Authors and Affiliations
Z. Konopka, S. Holecek, J. Pożar, M. Nadolski, A. Zyska
Keywords
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