| Abstract Scope |
Carbon-based materials are light, strong, highly conductive, thermally stable, and possess good chemical resistance. These materials include structured graphene, carbon nanotube (CNT) materials, and carbon fiber (CF) reinforced thermoplastic composites. In this work the authors will demonstrate joining technologies for carbon-based materials to other materials to fabricate functional composites. The authors will show that these joining interfaces can be fabricated for low electrical resistance, high temperature applications, and to provide good mechanical strength.
First, joining methods for lower temperature applications will be presented. The focus is on continuous fiber reinforced thermoplastic composites (CFRTPCs). The continuous fibers studied were carbon and glass and the thermoplastics included polyamide (PA), polyetherimide (PEI), and polyphenylene sulfide (PPS). The materials combinations joined were CFRTPCs to themselves, metal, and glass. The technologies used to join them include pulsed laser etching and continuous laser joining. They were joined at speeds of up to 200 cm2/min with strengths up to 24 MPa. These types of composites are well suited for military land, sea, and air vehicles.
Next, joining methods for higher temperature applications will be presented. The systems studied were CNT fabrics and fibers joined to 304 stainless steel. Three different joining technologies were developed for these systems. In increasing order of temperature resistance, they were silver epoxy, ultrasonic soldering, and brazing. The brazed samples contained a small amount of titanium to provide strong, low electrical resistance joints through titanium carbide bonds. The brazed composites are stable to nearly 1000°C and can be used for cathodes in high powered microwave devices, or structural composites for attritable or durable systems.
Overall, each novel joining technology has applications for manufacturing defense or commercial products. These processes are scalable to produce next generation products with enhanced environmental survivability. |