Additive Manufacturing of Haynes 230 Carbon Nanotube Metal Matrix Composites for Propulsion Applications

The purpose of this phase II SBIR proposal is to transfer knowledge and expertise in the Additive Manufacturing of Haynes 230 carbon nanotube metal matrix composites developed under Air Force STTRs 20D-TSCO1 and 21B-TSCO1, and utilize the mechanical and thermal physical properties demonstrated under these efforts, and demonstrate their utility for use in jet engine applications. The core innovation is the ability to process carbon nanotubes and integrate them with any powder metal alloy composition for use in metal Additive Manufacturing.    This innovation has been demonstrated in recent years through multiple SBIR and STTR efforts conducted on behalf of the Navy (Phase I/II STTR N16A-T007), the Army (Phase I/II SBIR A17-033), and the Air Force (Phase I SBIR AF182-005 and Phase I/II STTRs AF20D-TSC01, AF21B-TSC01, and D2P2 SBIR AF234-DSCO1).  This innovation yields a two-phase composite in which the carbon nanotubes serve as a strengthening filament within the metal matrix . This is the result of an electron bond formed between the d-orbital electrons of the metal matrix and the ?-orbital electrons of the SP2 hybridized carbon atoms in the carbon nanotubes (CNTs). This SP2 covalent bonding arrangement of the carbon atoms in the carbon nanotubes results in a material that is stronger, stiffer, and lighter than the metals used as matrix materials. Through the prior SBIR and STTR programs, technical uncertainty regarding the viability of CNMMC technology has been eliminated, as benefits have been demonstrated in aluminum, nickel, stainless steel, and copper alloys.  What remains is the engineering optimization of production processes and the establishment of material property databases.   In addition to improved mechanical properties, the use of CNTs has other benefits.  The SP2 bonding arrangement of the carbon atoms in the CNTs results in high thermal and electrical conductivities.  With the volume loadings of the CNTs typically used in these carbon nanotube metal matrix composites (CNMMCs), a percolation effect is achieved, increasing the overall thermal and electrical conductivity of the composite.