Fasteners/Rivets for Watertight Integrity and Corrosion Prevention in Permanent Application

Wet install” rivets/fasteners use two-part sealants that are hand brushed onto the sleeve just prior to installation – associated labor and schedule costs are significant, and quality variation can be high. Rivets with a pre-applied sealant are an obvious but technically challenging solution. To get cure-in-place seals on rivets/fasteners means blocking sealant cure until installation. Cure blocking will be done by modifying AMS3281/3276 and AMS3277 sealants. Shelf plus application lifetimes are estimated at well over 1 year. Five blocking techniques will be examined and tested, along with development of a size coat to protect the cure blocked sealant from moisture and handling damage that can cause premature cure. Blocking strategies include anhydrous, microencapsulation, appending a blocking molecule that is cleaved by moisture, using a nanoclay blocking carrier, and A/B parts in nanocomposite friable shells – all with cure initiated by installation force. Non-chromate corrosion inhibitors (NCCIs) and colorants to indicate premature cure are built-in. NCCIs will be selected from state-of-the-art options proven in long term corrosion tests. Final sealant prototypes will be tested to AMS standards. A fastener manufacturer will test prototype self-seal rivets for installation and sealing, and conduct a machine design study for automating the production of self-seal rivets/fasteners.