Friction stir extrusion of aluminum AA6061 into isostatically molded graphite

This work investigates existing metal-graphite joining methods with friction stir extrusion (FSE) proposed as a viable alternative joining process. Current joining methods for these materials, including adhesives, mechanical fastening, and brazing, all have shortcomings that are desired to be avoided. Aluminum AA6061-T6 is used with isostatically molded graphite to establish a proof-of-concept for metal-graphite FSE. Empirically determined operating conditions were established that reduced force spikes, vibration, and FSE flaws while preventing significant defects in the final product. Successful metal-graphite FSE joints were created and tested in lap shear compression loading. A comparison of the FSE joint strength to the strength of brazed joints is presented. Metalgraphite FSE is concluded as a viable joining technique in low-load applications. Process optimization for future work and methods of joint strength enhancement are discussed.