Laminated structures comprised of mostly brittle constituents offer promise in a wide range of applications of national interest. These include: Hot section components in aircraft engines, pavement materials for airfields and roads, and electronic packaging. A combined fabrication, experimental and theoretical study of the mechanical properties of bioinspired MEMS (microelectromechanical systems) composites will be supported under an SGER award. The results will impact the development of improved synthetic ceramic-based laminates. The inspiration for this proof-of-concept effort comes from mollusk shells, which are naturally-occurring ceramic/polymer composites, with a very high volume content (95-99%) of the ceramic phase, a small quantity of organic (proteinaceous) "matrix" (1-5%), and which show impressive and unusual strength, toughness, and hardness. The microarchitecture of mollusk shells will be approximated in MEMS structures by alternating layers of silicon carbide (to imitate the ceramic phase in the shells) and carbon (to imitate the relatively weak protein interphase). This part of the research not only will verify that the experimentally-identified shell microarchitectures and fracture/deformation mechanisms can be utilized to make bioinspired strong, tough and hard materials, but will also contribute to the development of MEMS fabrication technology, and to other electronic devices with superior mechanical properties.
The proposed research involves the following tasks:
Task 1: Fabrication of model brittle matrix composites with bio-inspired laminated architectures.
MEMS technology will be used to design and fabricate a silicon carbide/carbon composite that mimics the crossed-lamellar structures of the shell of the giant pink conch, Strombus Gigas. The strength and toughness of this structure will be measured experimentally to assess how close the biomimetic design is to the natural design.
Task 2: Theoretical modeling of mechanical response.
The interpretation of experimental results, and determination of the essential features of the natural designs that lead to optimization of mechanical properties will be supported by micromechanical and global models to be developed as part of the research.