Assessing the Corrosion Resistance of Metal Matrix Composite Materials in Marine Environments

Aylor, DM; Kain, Robert M.

doi:10.1520/stp32817s

Cited by 18 publications

(9 citation statements)

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“…Thus, the service life of Gr/A1 composites is determined solely by the corrosion resistance of the aluminum surface foils. This has also been reported by other researchers (33,34), who suggested that the accelerated corrosion following penetration is due to anodic polarization of the aluminum by the graphite, i.e., classical galvanic corrosion. I.…”

Section: Resultssupporting

confidence: 85%

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Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Aylor

Moran

1985

J. Electrochem. Soc.

149

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This paper examines the effect of graphite and silicon carbide reinforcements on the pitting behavior of graphite/aluminum (Gr/Al) and silicon carbide/aluminum (SiC/A1) metal matrix composites. Electrochemical corrosion tests were performed on both Gr/A1 and SiC/A1 composite specimens. Identical tests were completed on powder metallurgy processed aluminum and wrought aluminum of the same composition. The electrochemical behavior of the SiC/A1 composites was essentially identical to that of the powder processed and wrought aluminum alloys; however, the pitting attack on the SiC/Al composites was distributed more uniformly across the surface, and the pits penetrated to significantly less depths. The presence of graphite in the Gr/A1 composites did not cause an electropositive shift in corrosion potential as anticipated, but caused a substantial decrease in resistance to passive film breakdown. This effect is the predominant reason for the poor performance of Gr/At composites in marine environments.Interest in implementation of metal matrix composites (MMC) in marine applications is rapidly expanding due to the materials' higher strength and modulus than that which can be attained by conventional alloying. Utilization of MMC in marine environments requires adequate corrosion resistance. To date, composites considered for marine application are typically aluminum-based, specifically 5000 series or 6061 Al, with reinforcements of graphite (Gr) and silicon carbide (SIC). It has been reported tl~at aluminum alloys suffer localized attack by pitting in chloride environments (1, 2). A reinforcement of Gr or SiC added to the aluminum matrix could potentially decrease the corrosion resistance as compared to an unreinforced alloy due to the structure of the composite. Continuous graphite/aluminum (Gr/A]) composites typically consist of Gr/Al wires (graphite multifilament tows infiltrated with aluminum) diffusion bonded between aluminum foils. This composite configuration could promote wicking of the electrolyte (thereby increasing the corrosion rate) at the foil-to-wire and wire-to-wire interfaces once pitting corrosion progresses through the aluminum foils. The structure of the discontinuous silicon carbide/aluminum (SiC/A1) composites, that of silicon carbide whiskers or particles blended into a powder aluminum matrix could increase the probability of pitting/crevice corrosion at exposed SiC-A1 interfaces in the composite. Dull et al. (3,4) studied the Gr/A1 system in 3.5% NaC1.They concluded that the corrosion rate was slightly higher for Gr/AI relative to 6061 aluminum alloy controls. The explanation for this increased corrosion rate was galvanic corrosion at the graphite fiber-aluminum interface.Trzaskoma et al. (5) studied the SiC/A1 system in 0.1N NaC1. They concluded that the SiC whiskers did not influence the susceptibility of 6061 aluminum to pit initiation, but promoted the development of a smaller size pit morphology relative to 6061 aluminum controls.In this research, both SiC/A1 and Gr/A1 composites were evalua...

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Section: Resultssupporting

confidence: 85%

“…Marine exposures.--A thorough review of the marine exposures.for Gr/6061 A1, SiCw/6061 A1, and 6061-T6 Al is covered elsewhere (33). The major results of the above panel exposures as well as exposures of SiCw/6061-T6 A1 and PM6061 A1 are described in this section.…”

Section: Resultsmentioning

confidence: 99%

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Aylor

Moran

1985

J. Electrochem. Soc.

149

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“…However, insufficiently alloyed materials pose a risk for corrosion when implanted in the body owing to local galvanic cell formation at the interface of different metals. For example, accelerated corrosion of conductive graphene/ Al composites compared with SiC/Al composites has been reported in a marine environment 23) . Therefore, the completely-alloyed materials used in this study are likely to be overall more effective in biomedical applications.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of apatite formation on Ti-50Zr alloy in simulated body environment

2023

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Ti-50Zr alloy is 2.5 times as strong as pure Ti and has a lower Young's modulus, making it a useful material for repairing bone and teeth. However, Ti-50Zr alloy has a limited ability to bond with bone in vivo. Under biological conditions, apatite formation at the surface of a Ti or alloy implant is necessary for its bonding with bone. Various approaches to surface modification have been proposed to impart bone-bonding ability to Ti-50Zr alloy; however, there remains a need for further improvements to the alloy's apatiteforming ability. Hence, in this study, we compared apatite formation at the surface of alloy substrates in simulated body fluid, after various surface treatments. Treatment with 5 M NaOH followed by 1 M CaCl2 was the most effective procedure, whereas a sample subjected to a hot water post-treatment formed less apatite. Notably, no apatite formed on samples treated with 10 M NaOH.

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“…The only exception may be ferritic-austenitic stainless steel. The literature [2][3][4][5][6][7][8][9][10] on the corrosion beha-viour of MMCs has shown that the presence of a reinforcing material may or may not increase the corrosion susceptibility, depending not only on the metal-reinforcement combination but also on manufacturing process parameters. In this work, corrosion characteristics were examined and compared for three Al 7075-based MMCs prepared in the laboratory using the same procedure with carbon nanotubes (CNT).…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behaviour of CNT Reinforced AA 7075 Nanocomposites

Thirumaran¹

2013

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Carbon nanotubes reinforced AA 7075 alloy was fabricated by powder metallurgy route. Multi-walled carbon nanotubes (MWCNTs) were synthesized by electric arc discharge method. Different mass fraction of CNTs was added to the AA 7075 and the powder mixtures were consolidated using uniaxial press. The consolidated samples were sintered at 600˚ C in inert atmosphere followed by hot compaction at 450˚ C. The electrochemical corrosion behaviour of AA 7075 and CNT reinforced AA 7075 was studied using Electrochemical Polarization Technique (ACM Gill) and Electrochemical Impedance Technique. The relative densities of the composites were measured. The phase analysis and surface morphology of the composites were done by XRD and scanning electron microscope (SEM). The corrosion behaviour of the composites and the possible mechanism for the effect of CNT in the properties have been studied in detail in this paper.

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Assessing the Corrosion Resistance of Metal Matrix Composite Materials in Marine Environments

Cited by 18 publications

References 0 publications

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Effect of Reinforcement on the Pitting Behavior of Aluminum‐Base Metal Matrix Composites

Enhancement of apatite formation on Ti-50Zr alloy in simulated body environment

Corrosion Behaviour of CNT Reinforced AA 7075 Nanocomposites

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