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DIRECTED ENERGY PROFESSIONAL SOCIETY

Abstract: 24-Symp-217

UNCLASSIFIED, PUBLIC RELEASE

MEDAL: A Graphene-Nanodiamond Composite for Enhanced Electromagnetic Shielding and Mechanical Protection

The increasing threat of electromagnetic pulse (EMP) attacks and the need for advanced materials that can provide both mechanical protection and electromagnetic shielding have driven the development of innovative material solutions. In this work, we present MEDAL (Multi-threat Engineered Diamond Armor Layer), a novel graphene-nanodiamond composite material that offers exceptional mechanical properties and electromagnetic shielding capabilities.

MEDAL is fabricated through a unique process developed by researchers at the University of Massachusetts Amherst, which involves the controlled formation of sp3 carbon-carbon bonds between layers of graphene. By tailoring the interlayer bonding and stacking configuration, MEDAL can be tuned to exhibit a combination of high strength, stiffness, and toughness, surpassing the mechanical performance of conventional armor materials such as high-strength steels, ceramics, and composites.

Molecular dynamics simulations predict that MEDAL can achieve an elastic modulus of 650-870 GPa, a tensile strength of 30-100 GPa, and a toughness of 2-5 J/m2, while maintaining a low density of 2-3 g/cm3. These properties enable the design of ultra-lightweight, high-performance armor systems that can provide superior protection against ballistic impacts, blast waves, and other mechanical threats.

In addition to its exceptional mechanical properties, MEDAL also exhibits promising electromagnetic shielding capabilities. The layered structure of the graphene-nanodiamond composite, with alternating conductive graphene layers and insulating sp3-bonded interlayers, creates a built-in capacitive effect that can absorb and dissipate electromagnetic energy. By selectively doping the graphene layers and optimizing the interlayer bonding, the electromagnetic shielding performance of MEDAL can be further enhanced.

To maximize the electromagnetic shielding effectiveness while retaining the excellent mechanical properties, we propose a multi-functional MEDAL architecture that combines a graphene-nanodiamond composite core with pristine graphene outer layers. The core provides the structural reinforcement and energy absorption, while the pristine graphene layers, which are not treated with plasma, serve as a highly conductive shield against electromagnetic radiation. This configuration leverages the semi-metallic nature of graphene, which is more effective for electromagnetic shielding compared to the wide bandgap semiconductor properties of diamond.

The versatility of the MEDAL fabrication process allows for the material to be applied as a spray coating using cold spray or plasma spray techniques. This enables the retrofitting of existing structures and vehicles with a protective MEDAL layer, enhancing their survivability against both mechanical and electromagnetic threats. The spray coating approach also facilitates the integration of MEDAL with other materials and structures, enabling the design of multi-functional armor systems.

To assess the performance of MEDAL, we have conducted a series of computational studies and small-scale experiments. Finite element simulations of MEDAL-coated structures subjected to high-velocity impacts and blast loads demonstrate the material's ability to absorb and dissipate energy, reducing the risk of penetration and structural failure. Electromagnetic shielding tests conducted on MEDAL samples show a significant reduction in transmitted electromagnetic energy.

In conclusion, MEDAL represents a groundbreaking material solution for combined mechanical protection and electromagnetic shielding. By leveraging the unique properties of graphene and nanodiamond, and through the precise control of interlayer bonding and multi-functional layering, MEDAL offers unparalleled performance and versatility for a wide range of defense applications. Further research and development efforts are underway to optimize the material composition, processing parameters, and scaling up the production of MEDAL for practical implementation. With its exceptional mechanical properties and electromagnetic shielding capabilities, MEDAL has the potential to revolutionize the design of armor systems and protective structures, enhancing the survivability and mission readiness of our armed forces in the face of emerging threats.

UNCLASSIFIED, PUBLIC RELEASE