College of Arts and Sciences Publications and Scholarship

Abstract

Scanning electrochemical microscopy (SECM) is used to image variations in electrochemical activity over the surface of an aluminum-based metal matrix composite (MMC) in contact with buffered or unbuffered neutral solutions. The composite consists of an Al - 13.5% Si - 9% Mg alloy matrix and reinforcing silicon carbide particles (SiCp). Feedback mode SECM imaging using ferrocenemethanol as a redox mediator in 0.1 M NaCl solution and in buffer solution (pH 6.8) revealed that the SiC particles are electrochemically active. The data suggest that the electronic conductivity at these sites is higher than that of the Al2O3 film covering the alloy matrix surface. The reduction of dissolved oxygen on the silicon carbide particles was investigated by in situ SECM images of samples and current vs. tip-substrate distance curves. The results with samples of SiCp/Al composites immersed in distilled water alone or in either 0.1 M NaCl or boric acid/borax buffer containing ferrocenemethanol as mediator demonstrate that the silicon carbide particles are conductive and act as local cathodes for the reduction of oxygen.

Comments

Postprint manuscript of the accepted article

Publisher

The Electrochemical Society

First Page

B299

DOI

https://doi.org/10.1149/1.1737384

Publication Date

2004

College

College of Arts and Sciences

Department

Department of Chemistry

Keywords

Chemistry, Corrosion, Electrochemistry, Scanning Electrochemical Microsopy, Aluminum, Silicon Carbide, Composites, Metal Matrix Composites

Disciplines

Analytical Chemistry | Materials Chemistry

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