A technique for determination of cathodic activity during corrosion of a metal matrix composite
- Univ. of Delaware, Newark, DE (United States). Materials Science Program
During the aqueous corrosion of aluminum in the presence of oxygen, Al loses electrons to form Al{sup 3+} ions and the O{sub 2} is reduced and forms (OH){sup {minus}} ions. These reactions occur at local anodic and cathodic sites and it is difficult to determine where the micro-cathode is for several reasons. In this research, Al specimens were immersed in 3.5 wt% NaCl solution containing also 0.5--1 ppm of PdCl{sub 2}. During the corrosion process the Pd{sup 2+} ions gain electrons at the micro-cathodic sites and are deposited there. Pd distribution micrographs can then be easily obtained in the SEM due to the great atomic weight difference between Al and Pd. The Pd distribution micrographs can be used directly to demonstrate the cathodic activity of very fine microstructural features such as precipitates and 0.5 {micro}m diameter SiC whiskers. Results from two aluminum matrix composites are reported. The first is a SiC whisker reinforced 2124 composite (SiC{sub w}/2124), the other is an alumina particulate reinforced 6061 composite (Al{sub 2}O{sub 3}/6061).
- OSTI ID:
- 205229
- Journal Information:
- Scripta Materialia, Vol. 34, Issue 7; Other Information: PBD: 1 Apr 1996
- Country of Publication:
- United States
- Language:
- English
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