Title: Corrosion behaviour of aluminium syntactic functionally graded composites

Authors: S.C. Ferreira, A. Velhinho, R.J.C. Silva, L.A. Rocha

Addresses: Faculty of Science and Technology, CENIMAT/I3N, Materials Research Centre, Materials Science Department, New University of Lisbon, Quinta da Torre, 2829-516 Caparica, Portugal. ' Faculty of Science and Technology, CENIMAT/I3N, Materials Research Centre, Materials Science Department, New University of Lisbon, Quinta da Torre, 2829-516 Caparica, Portugal. ' Faculty of Science and Technology, CENIMAT/I3N, Materials Research Centre, Materials Science Department, New University of Lisbon, Quinta da Torre, 2829-516 Caparica, Portugal. ' CT2M, Centre for Mechanical and Materials Technologies, Mechanical Engineering Department, University of Minho, Guimaraes 4800-058, Portugal

Abstract: Syntactic Functionally Graded Metal Matrix Composites (SFGMMC) are a type of composites reinforced by microballoons exhibiting a graded reinforcement distribution. These materials constitute a promising new generation of lightweight structural materials for aerospace, marine and shielding/insulation applications. In this work, A356 alloy reinforced with silica-alumina microballoons (SiO₂-Al₂O₃) was processed by casting techniques. The influence of the microballoon distribution gradient on the corrosion behaviour of the composite was investigated by potentiodynamic polarisation and Electrochemical Impedance Spectroscopy (EIS). Composite surfaces were analysed before and after testing by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) to determine the influence of microstructural changes.

Keywords: syntactic aluminium foams; stir casting; functionally graded composites; centrifugal casting; corrosion; potentiodynamic polarisation; EIS; electrochemical impedance spectroscopy; functionally graded materials; FGM; microballoons; silica; alumina; microstructure.

DOI: 10.1504/IJMPT.2010.034265

International Journal of Materials and Product Technology, 2010 Vol.39 No.1/2, pp.122 - 135

Published online: 31 Jul 2010 *

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