The Evaluation of Ambient-Temperature Processes for Repair Bonding of Aluminum Alloys
Abstract
On-aircraft adhesive bonding of metal substrates typically requires the use of impractical surface preparation processes in order to attain the desired bonded joint strength and durability. Surface preparations currently used for on-aircraft repairs rely on hazardous materials and/or inconvenient processing steps, or they do not yield adequate bond performance. Many U.S. Air Force Technical Orders (T.O.s) require the use of surface preparations such as phosphoric acid anodize (PAA) or acid paste etches for the repair of aluminum alloy structure. These surface preparations are often impractical due to difficulties imposed by the of aircraft use of acids or the extended time required for their application. The phosphoric acid in PAA and sulfuric acid used in common paste acid etches are difficult to contain and can embrittle certain high-strength steels'. In addition, the acids must be rinsed after application and could cause collision of metallic structure if not completely removed. The grit-blast/silane surface preparation employed in many repair applications provides an alternative to the use of acids but requires a grit-blasting step, elevated-temperature drying, and several hours to perform. The use of hazardous materials in these surface preparations is becoming more difficult due to existing and proposed environmental and health regulations. The combination of these regulations and the need to reduce environmental waste stream while maintaining adequate bond performance has lead to the development of more environmentally friendly processes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2002
- Accession Number
- ADA408217
Entities
People
- Daniel B. Mccray
Organizations
- University of Dayton