Researchers ask industry for ways to build ceramic materials with the strength of metal for submarine hulls

ARLINGTON, Va. – U.S. military researchers are asking industry to explore new approaches to produce monolithic ceramic materials tough enough for use in building aircraft airframes, ground vehicle chassis, and submarine hulls.

Officials of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., issued a solicitation earlier this month (DARPA-PA-24-04-06) for the Intrinsically Tough and Affordable Ceramics Today (INTACT) project to explore atomic-scale toughening mechanisms for ceramics with the pliability and strength of metal.

Researchers particularly are interested in the application of emerging nonequilibrium processing techniques to engineer defects like vacancies, dislocations, phase, and grain boundaries into ceramic materials to accommodate fine-scale plastic deformation.

Similar to forging

Introducing mechanical work -- similar to forging -- and rapid thermal quench rates accessible via laser, electron beam, and other far-from-equilibrium processing techniques opens new possibilities to create radically new ceramic microstructures that may enable breakthroughs that increase bulk fracture toughness levels while maintaining an impressive balance of properties, DARPA researchers explain.

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In integrated circuits, ceramic materials primarily are for substrates to provide a stable base for electronic components due to their high thermal conductivity, high electrical insulation, and dimensional stability.

Structural applications, however, demand materials with high strength, stiffness, environmental resistance, and fracture toughness. Ceramics generally outperform metal in all these properties except fracture toughness.

Critical structures

The lack of fracture toughness in ceramics has prevented their use in critical structures such as airframes, turbine disks, ground vehicle chassis, and submarine hulls. This is unfortunate, as structural ceramics have the potential to be 10 times stronger than metals, are two times stiffer, half as dense, are capable of operating at two times higher temperatures, and can operate in corrosive environments.

Engineering metal-like fracture toughness into bulk ceramics would introduce a new class of damage-tolerant structural materials that potentially could exceed the capabilities of even the most advanced metallic alloys.

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The dream of tough ceramics has existed since at least the mid-20th century, but achieving metal-like toughness has not yet been realized. As a compromise, ceramic matrix composites have been developed that exhibit “quasi-ductility” owing to macroscopic interactions between reinforcing fibers and a ceramic matrix. While ceramic matrix composites have been applied in military and commercial applications, their manufacturability remains a significant challenge.

Focus on manufacturability

Skilled labor and specialized equipment are necessary to produce, coat, lay up fibers, infiltrate matrix material, and convert the material to a dense finished product. The INTACT program also focuses on manufacturability, with the goal of slashing lead times for structural hardware with flexural strength, fracture toughness, and cycle time.

The project's yearlong first phase will develop ceramic materials and processing approaches with flexural strength and fracture toughness. The yearlong second phase will improve materials and processes.

Companies interested should submit proposals no later than 14 March 2025 to the DARPA Broad Agency Announcement Portal online at https://baa.darpa.mil.

Email questions or concerns to Andrew Detor, the INTACT program manager, at [email protected]. More information is online at https://sam.gov/opp/1abdb144d6df4a40b5233596f8b5b6a0/view.