Imagine a protective coating that not only resists corrosion, but singlehandedly sniffs it out even before it’s visible and springs into action to repair the damage.
NASA scientists say they have just such a “smart coating” in the pipeline.
The space agency reports that it is developing a multifunctional smart coating that controls corrosion “autonomously” using pH-sensitive microcapsules.
The microcapsules are designed to detect the pH changes associated with the onset of corrosion, respond autonomously to indicate its presence early, control it by delivering corrosion inhibitors, and deliver self-healing or film-forming agents capable of repairing mechanical damage to the coating.
Launch Pad Corrosion
Scientists at the Kennedy Space Center are working with Greenbelt, MD-based ASRC Aerospace Corp. on the coating, which they hope to use initially on launch-pad corrosion.
The launch environment at the Kennedy Space Center is extremely corrosive, comprised of ocean salt spray, heat, humidity, sunlight and acidic exhaust from solid rocket booster (SRB) exhaust.
|Launch pad corrosion at the Kennedy Space Center costs NASA $1.6 million a year.|
The center spends $1.6 million each year for corrosion control on the launch pads. Researchers say the coating could save KSC $132 million over 20 years.
“Smart Coatings”—the Holy Grail of coatings research—interact with their environment, unlike conventional coatings that passively protect the substrate after application. Smart coatings are engineered to sense a change in the environment and respond to the change in a predictable, reliable manner.
Microcapsules are polymer-coated particles or liquid drops that can carry a material that needs protection or controlled release, or to compartmentalize multiple-component systems.
With NASA’s coating, various pH-sensitive microcapsules with hydrophobic or hydrophilic cores were synthesized through interfacial polymerization reactions in emulsion. The process was optimized to obtain mono-dispersed microcapsules in a size range suitable for incorporation into commercially available coatings.
The microcapsules can be obtained in suspension or in free-flowing powder form, NASA said.
Preliminary results from salt fog testing of panels coated with the technology “showed the effectiveness of the corrosion indicator in detecting hidden corrosion” and delivering inhibitors, according to NASA.
The coating detected the corrosion “at a very early stage,” NASA reported in February at Smart Coatings 2011 in Orlando.