Corrosion behavior of alumina-aluminum and silicon carbide-aluminum metal-matrix composites

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Corrosion

DOI:https://doi.org/10.5006/1.3293621· OSTI ID:103960

Nunes, P C.R.; Ramanathan, L V ^[1]

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1. Cidade Universitaria, Sao Paulo (Brazil)

Particle-reinforced, aluminum-based metal-matrix composites (MMCs) are being considered for a range of applications. Their mechanical properties have been investigated in detail, but more information about their corrosion behavior is needed. the influences of alloy composition; particle characteristics such as composition, size, volume fraction, and pretreatment; and composite post-treatment on the aqueous corrosion behavior or aluminum-matrix composites prepared by the melt stirring process were studied. Corrosion tests consisted or prolonged immersion and anodic polarization measurements in sodium chloride solutions. The difference between the corrosion potential (E{sub corr}) and the pitting potential (E{sub p}) was lowered from {approximately} 500 mV{sub SCE} in deaerated NaCl to 100 mV{sub SCE} in aerated NaCl. Particle addition affected E{sub p} but not E{sub corr}. Immersion test data revealed significant specimen weight loss for the composites resulting from formation of pits or microcrevices in the matrix near the particle-matrix interface and from particle dropout. Pits in the silicon carbide composites were deeper than those in the alumina composites, probably because the SiC particles acted as efficient cathodic sites. Pit initiation and propagation occurred at weak spots in the air-formed film corresponding to phase discontinuities and second-phase particles sand to oxygen reduction at the particles or precipitates. Anodization and ceria coating improved corrosion resistance of the composites.

• Sponsoring Organization: USDOE
• OSTI ID: 103960
• Journal Information: Corrosion, Journal Name: Corrosion Journal Issue: 8 Vol. 51; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
CERIUM OXIDES
COMPOSITE MATERIALS
CORROSION
CORROSIVE EFFECTS
CREVICE CORROSION
ELECTROCHEMICAL CORROSION
PARTICULATES
PITTING CORROSION
PROTECTIVE COATINGS
SILICON CARBIDES
SODIUM CHLORIDES