NONMETALS TEST AND EVALUATION Delivery Order 0007: The Development of On- Aircraft Surface Preparations Utilizing Sol-Gel Coatings for Adhesive Bonding Aluminum Alloys

Abstract : High-performance surface preparations for adhesive bonding of metals typically require the use of strong acids or bases, volatile organic compounds (VOCs), and hexavalent chromium. Surface preparations used for on-aircraft repair of aluminum rely on hazardous materials or inconvenient processing steps, or they do not yield adequate bond performance. Grit-blast/silane (GBS)', phosphoric acid containment system (PACS)2, which is a version of phosphoric acid anodize (PAA)3, and certain acid paste etches are the high-performance surface treatments currently available for on-aircraft application. All are used in conjunction with chromated, high- VOC primers. All are time consuming for on-aircraft repair. Furthermore,, their use is becoming more difficult due to existing and proposed environmental, safety, and health regulations.