The objective of this project is to leverage and advance the work performed under the SERDP SEED project, "Introducing Interfacial Bond Failure at the Elastomer-Primer Interface Using Tailored Infrared-Sonication Hybrid Technology" (WP18-1347). The findings from this project revealed that the fracture energy component is four times lower on the radiation treated sample than the untreated sample indicating reduced interfacial bond strength and usefulness of the technology. The current effort is to develop further the innovative coating removal process for the removal of thick elastomeric coatings and treatments from the outer mold line of US Air Force (USAF) and US Navy (USN) weapon systems. The present endeavor is a full scope of work to develop and use infrared (IR) and ultrasonication technologies for coating removal based on the concept of introducing interfacial bonding failure at the surface coat-substrate interface by selective absorption of IR radiation emitted from an IR source. Induced stress at the interface allows the coatings to be removed entirely using an ultrasonication scraper/probe. The project team will assess the efficacy of the coating removal process for the removal of thick elastomeric coatings, such as rain erosion coating and sealants, from metal and composite aircraft structures. The development will meet the SERDP objective of providing complete aircraft surface coating removal with reduced cycle time, optimum cleanliness, air quality standards, and equivalent or better cost-effectiveness as current baseline coating removal processes.
The approach is based on the concept of introducing interfacial bonding failure at the surface coat-substrate interface by selective absorption of IR radiation emitted from an IR source alone. The induced stress at the interface due to the exposure of IR degrades the interfacial adhesion strength. It allows the coatings to be removed entirely using an ultrasonication scraper/probe.
Infrared and ultrasonication elastomeric coating removal is an environmentally friendly method that does not produce a secondary waste stream, reduces, or eliminates worker exposure to hazardous materials, and eliminates the hazardous waste streams and air emissions associated with wheat starch, chemical strippers, and hand sanding. Additional benefits include reduction of blast media, coating/sealant stripping chemicals, spent personal protective equipment, masking materials, and an overall reduction in maintenance costs and process flow days associated with current methods. An automated removal process is expected to reduce labor costs and long-term impacts and costs associated with worker damage to hands, wrists, and other joints caused by ergonomically challenging manual and media blasting methods currently used for specialty coating and sealant removal.