The Boeing Company

University of Virginia Patent Foundation

S Ray Taylor

Kay Youngdahl Blohowiak

Harold E Hager

Chris J Johnson

John H Jones

Robert L Cook, Jr

Chun M Wong

Patrick A Cella

The invention provides chromate-free coating mixtures, and coatings formed from these mixtures, that protect an underlying aluminum or aluminum alloy substrate from corrosion. The coating mixtures include a continuous phase selected from organic polymeric compositions, or sol-gels, and a distributed phase, dispersed or dissolved throughout the continuous phase. The distributed phase includes the corrosion-inhibiting chromate-free salts. In accordance with the invention, the mixture of salts includes (1) a first salt selected from (a) the esters of rare earth metals, such as cerium and lanthanum oxalates and acetates, and (b) the vanadate salts of alkali and alkali earth metals, such as sodium metavanadate and calcium metavanadate; and (2) a second salt that is a borate salt of alkali earth metals, such as barium metaborate. In certain embodiments, the coatings of the invention include both (a), and (b), in conjunction with the borate salt (2). In other embodiments, the chromate free salt is a chloride of a rare earth metal, or mixture of such chlorides, either alone or in combination with the first salt or the second salt, or both the first and second salts. Coatings of the invention provide protection to an underlying substrate, even after subjection to a 3000 hour salt spray test. Moreover, the coatings are resistant to degradation by SKYDROL, and are able to withstand impacts of 50 inch-pounds (forward) and 30 inch-pounds (reverse), so that they are well suited for use as protective coatings for aircraft.

Chromate-free protective coatings

An in situ sensor for monitoring the degree of corrosion of rebar in a concrete structure relies on a four-point resistance measure of a test wire embedded in the concrete structure. The resistance across the wire is compared with the resistance of a reference wire, which is corrosion resistant. As corrosion advances, the cross-sectional area of the wire decreases, effectively increasing the resistance measured. The sensor may be used to measure corrosion inhibitor performance, and the effect of dilution.

In situ sensor for critical corrosion conditions in a material

Growing community of inventors

Charlottesville, VA, United States of America

S Ray Taylor