Protective coating to retard crack growth in aluminum alloy

摘要

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.