Structural adhesive bonding of titanium alloys and other metals offers many advantages over mechanical fasteners, but requires careful surface preparation to avoid premature bond failure. The existing surface treatment options have significant disadvantages, including hazardous material usage, the potential for contamination from debris, and long treatment times. A media-free technology that addresses these issues could significantly alter the landscape and enable wider adoption and access to the superior properties of structural adhesive bonding. Adhesion promotion with atmospheric plasma surface treatment has emerged in recent years as a promising technology to complement, or possibly replace, current surface preparation techniques. The benefits of atmospheric plasma for cleaning, functionalizing, and otherwise preparing surfaces for enhanced bonding are well documented, and Atmospheric Plasma Solutions, Inc. (APS) has demonstrated that its unique high power, air-based PlasmaFlux™ technology can enhance the bonding of titanium alloys. The proposed work will begin a formal investigation into an improved process using plasma to bond titanium alloys and other materials, including optimization trials and materials testing with ASTM protocols. APS will utilize its wealth of experience with multiple forms of atmospheric plasma technology to improve surface preparation for bonding and related applications in aerospace fabrication and maintenance.
Benefits: Existing titanium adherent preparation involves many steps to produce a high strength, consistent bond. Atmospheric plasma has the potential to eliminate multiple steps in the complicated process which will reduce the time required for repairs and reduce probability of improper surface preparation technique. Furthermore, existing surface preparation techniques rely on media (e.g. abrasives), solvents, other chemicals and coatings which often contain hazardous materials and can present environmental challenges and added compliance and disposal costs, in addition to the cost of the media and chemicals themselves. Adhesion promotion with atmospheric plasma, on the other hand, requires no media, solvents, or chemicals, generates no waste streams, and presents no undue occupational or environmental hazards to the operators. The media-free technology requires only compressed air and electricity as inputs, and may be used on virtually any surface. The immediate benefit of this development is an efficient, environmentally-friendly process that will greatly improve structural bonding of titanium alloys and other materials systems. This technology is a true dual-use technology and with further development can provide a complete solution for surface preparation for bonding and a wide variety of other applications across the military and commercial sectors. The technology will provide the benefits of reduced capital and labor costs, improved environmental compliance, and improved strength and reliability of assemblies made using the plasma-based structural bonding process.
Keywords: Atmospheric plasma surface activation, enhanced surface energy, bondline cleaning and preparation, sol-gel bond primer replacement, plasma as a surfactant substitute, high temperature titanium adherends ,titanium and BMI carbon fiber composite bonding adhesion promotion
