SBIR-STTR Award

Control of adhesive bonding operations to guarantee reliable bond performance requires careful, quantitative bond surface control. This includes: i. Knowledge of detrimental contaminants present in the bonding environment, ii. Threshold amounts of these contaminants that cause degradation of bond performance, iii. Reliable methods for detecting these contaminants on the bond surface that can be practically deployed in manufacturing, and iv. Methods for successful remediation of contaminated surfaces.Contaminants to be evaluated include specific tapes and sealants known to leave residues of unknown effect, and representative mixtures of contaminants likely to encountered in a bonding environment. Handheld inspection tools to be used for detection and quantification of contaminants include infrared spectroscopy, X-ray fluorescence, Laser Induced Breakdown Spectroscopy, and contact angle measurements.Phase I work will focus on RT cure paste adhesives, known for sensitivity to contaminated bond surfaces. Effects of contaminants on adhesive bonds will be evaluated using double cantilever beam specimens.Remediation methods will include contaminant removal via solvent cleaning to a quantifiable endpoint followed by abrasion or plasma treatment to complete contaminant removal and create a quantifiable chemically active bond surface.Adhesive Bonding,contamination,Surface preparation,surface treatment

Aerospace manufacturing and repair environments are dependent on the formation of reliable structural bonds, which require chemically clean and activated surfaces. However, in practical manufacturing environments, long and uncontrolled periods between surface preparation and bonding are common, which can introduce contamination to the bonding surface, thereby decreasing reliability and performance of the bond. Prevention, detection, and remediation of contaminants on the surface will allow peak bond performance to be realized. Phase II will expand upon the range of contaminants that were studied in Phase I to include many materials found in current aerospace bonding environments. The ability to identify which contaminant is on the surface can also direct which remediation steps are necessary for surface preparation. Phase II will develop several techniques for detection of detrimental levels of contamination on composite surfaces to a level that is deployable in manufacturing and MRO environments. Finally, Phase II will demonstrate novel methods for protection of prepared bond surfaces as well as methods for remediation of compromised surfaces. The work proposed here will provide techniques for prevention, detection, and remediation of contaminants for aerospace structural bonds.