Lockheed Corporation

Richard L Smith

Robert N Miller

A fatigue crack growth retardant material for application to aluminum and alloys thereof utilizes certain organic nitrogen compounds and an elastomeric polymer compatible herewith with respect to the curing properties thereof as well as the ultimate properties of the material and capable of stabilizing the nitrogen compound so as to inhibit the evaporation thereof to the atmosphere. The material inhibits corrosion of and retards crack growth in aluminum and alloys thereof when applied thereto. The material has particular utility when applied to the surfaces of structural parts of aircraft and is utilized as a protective coating as well as a sealant, dependent upon the amount of solvent added to the polymeric elastomer.

Fatigue crack growth retardant material

A protective coating to retard crack growth in aluminum and aluminum alloys has particular utility when applied to the surfaces of structural parts of aircraft providing a crack growth inhibitor to a crack surface when and as it develops in such parts. This inhibitor is a compound having a vapor pressure high enough to volatilize the inhibitor and emit molecules which will react with the surface of the metal to form a protective film. It is blended within a selected primer and is thereby available for interaction with the surface and tip of any crack which may initiate beneath the primer. A topcoat of low-permeability polyurethane covers the inhibitor-reinforced primer to prevent escape of the inhibitor from the primer.

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Atlanta, GA, United States of America

Richard L Smith