Smart Coatings for Autonomous Corrosion Detection and Control

Abstract

Corrosion is the degradation of a material that results from its interaction with the environment. The environment at the Kennedy Space Center’s (KSC) Beachside Atmospheric Exposure Test Site near the launch pads have been documented by ASM International (formerly American Society for Metals) as the most corrosive in the United States. The 70 tons of highly corrosive hydrochloric acid that are generated by the solid rocket boosters during a launch exacerbate the natural corrosiveness of the coastal environment at the pads. Numerous failures at the pads are caused by corrosion of stainless steels, rebar corrosion, and the degradation of refractory concrete. Corrosion control of launch pad structures relies on the use of coatings and materials that can withstand the marine atmosphere as well as the launch conditions. Coatings are selected from the qualified products list (QPL) of the NASA Standard 5008A for Protective Coating of Carbon Steel, Stainless Steel, and Aluminum on Launch Structures, Facilities, and Ground Support Equipment. This standard was developed to establish uniform engineering practices and methods and to ensure the inclusion of essential criteria in the coating of ground support equipment (GSE) and facilities used by or for NASA. This standard is applicable to GSE and facilities that support space vehicle or payload programs or projects and to critical facilities at all NASA locations worldwide. In recent years, environmental regulation changes have dramatically reduced the availability of conventional corrosion protective coatings. Current attrition rate of qualified KSC coatings will drastically limit the number of commercial off the shelf (COTS) products available for future ground operations in support of launch operations at KSC. For this reason, corrosion detection and control technologies have been identified as a critical, initial capability technology need for ground processing of future launch vehicles, reduced ground processing complexity, streamlined integrated testing, and operations phase affordability and sustainability. Researchers at NASA’s Corrosion Technology Laboratory at KSC are developing a smart, environmentally friendly coating system for early corrosion detection, inhibition, and self healing of mechanical damage without external intervention. This coating is being developed using corrosion sensitive microcapsules and particles designed to deliver corrosion indicators, corrosion inhibitors, and self healing agents on demand when corrosion or mechanical damage to the coating occurs. This paper presents the results from progress made to date in developing a coating for the smart corrosion control of launch pad structures and GSC.