Testing and evaluation of nonchromated coating systems for aerospace applications

Osborne, Jason W.; Blohowiak, Kay Y.; Taylor, S. R.; Hunter, Chad N.; Bierwagon, Gordon; Carlson, B.G.; Dan, Bernard; Donley, M.S.

doi:10.1016/s0300-9440(01)00132-1

Cited by 128 publications

(63 citation statements)

References 3 publications

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“…[14][15][16][17] Such a use is principally conducted using alkoxides based on silicon (M ¼ Si, n ¼ 4) and zirconium (M ¼ Zr, n ¼ 4). The resultant sol-gel film is very smooth as is shown in Figure 1A; according to AFM and SEM studies R ms ¼ 0.3 nm, the thickness of the film is $1.5 mm, and the contact angle of the sol-gel film is 748 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Surface‐Modified Mesoporous SiO₂ Containers for Corrosion Protection

Skorb

Fix

Andreeva

et al. 2009

Adv Funct Materials

219

103

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The development of active corrosion protection systems for metallic substrates is an issue of prime importance for many industrial applications. The present work shows a new contribution to the design of a new protective system based on surface modified mesoporous silica containers. Incorporation of silica‐based containers into special sol–gel matrix allows for a self‐healing effect to be achieved during the corrosion process. The self‐healing ability occurs due to release of entrapped corrosion inhibitors in response to pH changes caused by the corrosion process. A silica–zirconia‐based hybrid film is used in this work as a coating matrix deposited on AA2024 aluminum alloy. Mesoporous silica nano‐particles are covered layer‐by‐layer with polyelectrolyte layers and loaded with inhibitor [2‐(benzothiazol‐2‐ylsulfanyl)‐succinic acid]. The hybrid film with nanocontainers reveals enhanced long‐term corrosion protection in comparison with the individual sol–gel films. The scanning vibrating electrode technique also shows an effective healing ability of containers to cure the corrosion defects. This effect is due to the release of the corrosion inhibitor triggered by the corrosion processes started in the cavities. The approach described herein can be used in many applications where active corrosion protection of materials is required.

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Section: Resultsmentioning

confidence: 99%

Surface‐Modified Mesoporous SiO₂ Containers for Corrosion Protection

Skorb

Fix

Andreeva

et al. 2009

Adv Funct Materials

219

103

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“…These phase-separated Al alloys are susceptible to galvanic corrosion due to their highly complex metal-in-metal composite form. Chromates in the form of pigments in primers and as pretreatments for the substrates perform exceptionally well in protecting these alloys from corrosion as they function uniquely as anodic and cathodic inhibitors at very low concentrations in electrolyte solutions, especially with chloride ions that affect Al substrates [27,28]. However, hexavalent Cr has been recognized as a human respiratory carcinogen, based on epidemiological and medical evidence accumulated for more than a century [29].…”

Section: Magnesium-rich Primermentioning

confidence: 99%

Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers) for Aluminum Alloys

Pathak

Mendon

Blanton

et al. 2012

Metals

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Abstract:Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers) as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD) to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

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“…So the simplest improvement to inhibitor design is to increase the functionality by finding compounds which play both a cationic and anionic inhibitive role. A large range of cations including Zn, Ca, and rare earths (Bohm, McMurray et al 2001;Du, Damron et al 2001;Kendig and Buchheit 2003;Taylor and Chambers 2008;Muster, Hughes et al 2009) have been combined with either organic (Osborne, Blohowiak et al 2001;Sinko 2001) (Voevodin, Balbyshev et al 2003;Khramov, Voevodin et al 2004;Blin, Koutsoukos et al 2007;Taylor and Chambers 2008;Muster, Hughes et al 2009) or inorganic (oxyanions, carbonates, phosphates, phosphites, nitrates, nitrites, silicate (Bohm, McMurray et al 2001;Sinko 2001;Blin, Koutsoukos et al 2007;Taylor and Chambers 2008)) compounds. Anions with dual functionality, such as some of the transition metal oxyanions which are both oxidants and anions, have been investigated extensively.…”

Section: Corrosion and Protectionmentioning

confidence: 99%

“…There is some evidence to suggest that initial high release of inhibitors may be facilitated through atmospheric exposure of the intact paint where penetration of water into the film "prepares" the inhibitor, probably via surface hydrolysis reactions, within the paint, for diffusion and release into the defect (Du, Damron et al 2001;Furman, Scholes et al 2006;Scholes, Furman et al 2006;Souto, González-García et al 2010). The presence of water in the film allows soluble inhibitor species to be released into the paint system and diffuse to the metal/coating interface to provide in-situ corrosion prevention or repair called pre-emptive healing (Mardel, Garcia et al 2011) (Zin, Howard et al 1998;Osborne, Blohowiak et al 2001). Thus it has been demonstrated that water can trigger cerium dibuthylphosphate (Ce(dbp) 3 ) release into an epoxy matrix resulting in improved adhesion and resistance to filiform corrosion attack through interfacial modification (Mardel, Garcia et al).…”

Section: Corrosion and Protectionmentioning

confidence: 99%