EVALUATION OF EPOXY PASTE ADHESIVES FOR REPAIR BONDING OF ALUMINUM ALLOYS

摘要

The U.S. Air Force currently authorizes use of Henkel's Hysol EA 9320NA epoxy pasteadhesive in conjunction with a nylon pad/sol-gel (NPSG) surface preparation to perform bondedrepairs to certain noncritical aluminum aircraft structure. This system was selected for use basedon a significant amount of testing performed by the Air Force Research Laboratory's MaterialsIntegrity Branch (AFRL/RXSA) and Warner Robins Air Logistics Center's EngineeringDirectorate (WR-ALC/EN) that showed adequate environmental durability of bonds fabricatedusing EA 9320NA and the NPSG surface preparation when no bond primer is used in theprocess. Although EA 9320NA has been successfully used in bonded repairs, several limitationsexist when using the adhesive for these applications, including relatively low lap shear strengthat elevated temperature, marginal peel strength, and limited pot life once mixed. In response,AFRL/RXSA evaluated additional epoxy paste adhesives in attempts to identify alternativecandidates that could minimize current repair application limitations. This paper provides resultsof the coupon testing to date, including environmental durability (wedge test), tensile lap shear,and floating roller peel.