Corrosion protection of aluminum metal-matrix composites

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Corrosion

DOI:https://doi.org/10.5006/1.3290276· OSTI ID:619564

Greene, H J ^[1]; Mansfeld, F ^[2]

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1. Army Aviation and Troop Command, St. Louis, MO (United States)
2. Univ. of Southern California, Los Angeles, CA (United States)

Corrosion protection of aluminum metal-matrix composites (MMC) by anodizing treatments was investigated. Electrochemical behavior of MMC without protection also was investigated. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements were used to characterize the properties of protective surface layers. Materials studied were Al 6061/SiC, alloy A356/SiC, Al 2009/SiC, Al 2014/Al{sub 2}O{sub 3} and Al 6061/Al{sub 2}O{sub 3} with various reinforcement concentrations. The MMC had similar corrosion (E{sub corr}) and pitting (E{sub pit}) potentials as the matrix alloy. The cathodic current density for oxygen reduction in 0.5% N sodium chloride increased for Al 6061/SiC MMC with reinforcement concentration, which was attributed to electrochemically active interfaces between the matrix and the reinforcement particles. Anodizing and hot-water sealing were less effective for MMC than for the matrix aluminum alloys. The reinforcement particles produced a more porous structure of the anodized layer for MMC. Improved results were noted for dichromate sealing, where chromium (Cr{sup 6+}) in the pores of the outer oxide acted as an inhibitor. The effectiveness of corrosion protection methods decreased with increasing reinforcement concentration and was a function of the matrix alloy but not of the reinforcement material. The observed reduction in corrosion protection was believed to result from corrosion-susceptible interfaces formed between the reinforcement particles and the matrix.

• Sponsoring Organization: USDOE
• OSTI ID: 619564
• Journal Information: Corrosion, Journal Name: Corrosion Journal Issue: 12 Vol. 53; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
ALUMINIUM OXIDES
ANODIZATION
COMPOSITE MATERIALS
ELECTROCHEMICAL CORROSION
PITTING CORROSION
SILICON CARBIDES