STTR Phase I: Biomimetically Engineered Ceramics

This Small Business Technology Transfer Phase I project seeks to develop biomimetic structures in engineering ceramics based on the damage-tolerant sea shell micro-architecture. Poor damage tolerance of engineering ceramics leads to catastrophic failure modes under stress, which restricts their structural utility. In extreme conditions, ceramics generally function only as a thermal or chemical barrier. Gains in damage tolerance have been made in select ceramics via transformation toughening, acicular grains, and engineered architectures such as Fibrous Monoliths (FMs). Significant further gains can be achieved by mimicking the micro-architecture of the Strombus Gigas (sea shell). The multiscale architecture of the sea shell will be replicated in a model engineering ceramic system comprised of silicon nitride and boron nitride by borrowing and significantly building on the techniques used in making FMs, including thermoplastic deformation and assembly. Modeling of crack propagation through these complex architectures will be performed to help guide the development of the process. The microstructural, mechanical, and thermal properties of the engineered ceramics will be characterized. This research will establish the viability of the proposed thermoplastic deformation/assembly techniques to engineer a third-order biomimetic ceramic material which is expected to have a work-of-fracture more than twice as large as a comparable FM. The broader impact/commercial potential of this project will be the development of highly damage-tolerant ceramics that will increase their utility in engineering applications and validate bio-inspired materials engineering. The biomimetic ceramics will improve on the damage tolerance of existing ceramic systems by a significant margin and therefore will be of great interest to many industries: manufacturing, military/aerospace, and medical. No comparable technology exists which combines the benefits of ceramics (low density, thermal stability, high hardness) without their disadvantages (poor damage tolerance). Ceramic- and metal-matrix composites offer better reliability than bulk ceramics, but are expensive and often fall short of design requirements. Ultra tough ceramics will produce better performance in medical implants, maintain American manufacturing leadership, and promote advanced vehicle technology. By creating materials which can meet both thermal and structural requirements, this technology will create more multi-functional ceramics. Additionally, this project will lead to a better understanding of crack propagation through damage-tolerant hierarchical structures. Finally, the project will involve undergraduate and graduate students at Villanova University, and key results of the research will be disseminated in multidisciplinary conferences and journals.