Non-Polluting Composites Repair and Remanufacturing for Military Applications: Induction-Based Processing

The development of induction-based processing of carbon-fiber CF thermoplastic-matrix composites and accelerated cure of thermosetting adhesives has the potential to provide nonautoclave processing technology for manufacturing and repair of polymer-matrix composites PMCs. In this report, the results of recent tests demonstrating bonding of composites using commercial off-the-shelf thermal-cure adhesives that are heat cured via an induction field using an inductive susceptor are discussed. This method of cure utilizes heat generation within metal screen-based susceptors to cure the adhesive matrix via a heat transfer mechanism. The mechanical performance of these bonds is presented in comparison with autoclave and thermally cured baselines. No substantial loss of mechanical lap-shear strength is observed in adhesive bonds processed by induction. In addition, an example of induction welding of a thermoplastic-impregnated carbon fiber AS4 is presented. In order to successfully demonstrate induction welding for manufacture of CF composites, the degradation of the polymer in the laminates is also investigated. No measurable degradation of the polymer, either by dielectric or thermal breakdown when heated by induction, was observed.