engleski

Vapor phase inhibitors to extend the life of aging aircraft

Corrosion of aluminum alloys in the aircraft industry can cause expensive catastrophic failures, especially in aging aircraft. To further aggravate conditions, aircraft maintenance with conventional cleaning solutions can gradually destroy the protective aluminum oxide film and accelerate corrosion in crevices and lap joints. A new solution with corrosion inhibition properties used for washing/rinsing aircraft was investigated to determine the corrosion susceptibility for several aluminum alloys. The inhibitor chemical composition, as determined from XPS analysis, is a mixture of sodium compounds and hydrocarbon surfactant with uniform chemistry across the surface and minor variation of concentration with depth. Inhibitor effectiveness was confirmed with EIS and elevated temperature studies ; polarization resistance increased with concentration of inhibitor due to film formation and displacement of water molecules. Cyclic polarization behavior for samples in the inhibitor showed a shift in the passive film breakdown potential by roughly +600mV. The substantial increase in the passivation range has favorable consequences for pitting and localized cell chemistry. The strain at failure and tensile strength from the stress corrosion cracking studies pronounced effects at – 300 mV ; the fractographs showed an improved morphology with ductile overload as the primary failure mode.

SCC; vapor phase inhibitors; aging aircraft; aluminum alloys

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