Protective Coatings

• History of Coatings at KSC
• Coatings Evaluation and Testing

History of Coatings at KSC

Launch facilities at the Kennedy Space Center are approximately 1000 feet from the Atlantic Ocean. Salt from the ocean, combined with acidic rocket exhaust, makes corrosion a high priority issue at Kennedy Space Center. KSC’s Applied Technology Directorate has conducted research in the field of corrosion since 1968.

Testing of protective coatings for carbon steel, stainless steel, and aluminum has been an ongoing process for many years at KSC. In 1969, a testing program was initiated to evaluate coatings for the long term protection of carbon steel exposed to a sea coast environment. Both organic and inorganic zinc-rich coatings were applied to test panels and exposed at the KSC Beach Corrosion Test Site. These panels were evaluated for corr osion after 18 months, 3 years, 5 years, and 10 years exposure. The results of that study showed that the organic zinc-rich formulations did not perform well, but that the inorganic zinc-rich coatings displayed excellent corrosion protection.  Many inorganic zinc-rich coatings are still performing well today. Results obtained from the original report are shown below. While corrosion is apparent on the organic zinc panels on the left, no corrosion appears on the inorganic zinc panels on the right.

As a result of that study, inorganic zinc-rich coatings with no topcoat were used for many years at KSC for the long-term protection of carbon steel. Several of the single coated, inorganic zinc materials with no topcoat originally exposed for testing in 1969 are still providing complete protection to the carbon steel test panels at the KSC Beach Corrosion Test Site.

In 1981 the Space Shuttle launch system introduced a more aggressive environment to the Kennedy Space Center launch facilities. Exhaust from the solid rocket boosters included small particles of alumina with hydrochloric acid absorbed onto the surface of these particles. Wherever a cloud of this exhaust settled, unprotected zinc coatings were corroded. No inorganic zinc protective coating systems were immune to this new environment.  It was at this time that KSC launched a study of new coatings to resist this new, more aggressive environment.

At about the same time it became necessary to address new environmental regulations that limited the vapors that evaporate from coatings as they cure. New coating systems with lowered volatile organic compound (VOC) contents were included in a study starting in 1991 and continuing to this day.

Other coatings research has concentrated on developing smart coatings, self-cleaning coatings, conductive polymer coatings, coatings for stainless steel, silicone coatings for blast and heat protection on launch structures, and polysiloxane coatings.