The objective of this research is to enhance fundamental understanding of the correlation between complex hierarchical microstructure and the mechanical behavior of carbon/carbon composites. This is done by utilizing a multiscale model based on microstructural and mechanical characterization at nano to macro length scales. The model is validated by measuring the mechanical properties on all length scales. Participating investigators correlate microstructure and the mechanical properties with chemical vapor infiltration parameters. Stress concentrations and fracture induced by nanotexture of pyrolytic carbon and by thermal treatment of the composite are also investigated. The project is conducted in close collaboration by researchers from the University of New Hampshire (UNH) and the University of Karlsruhe (UKA), Germany. Material specimens are produced at UKA under controlled processing conditions. The micro and nanostructure of these specimens is characterized at UKA and UNH using various microscopies. Measurements of the micro-constituent mechanical behavior is performed at UNH using nanoindentation methods. Researchers incorporate this information in a unified predictive model of the overall mechanical response of the composite. Finally, macro-mechanical characterization of the material is conducted at UNH and at UKA using standard testing methods to validate the model.
The research will result in improvements in manufacturing of carbon/carbon composites that will benefit society mainly through technological advances in aeronautics and aerospace industries, although potential impact is also anticipated in emerging areas of applications of the composites such as biomedical devices, heating elements, and hardware for metal forming and glass making. The characterization and modeling approaches developed in this research will also be relevant to a wide class of composite and heterogeneous materials having complex nanostructures, including high performance ceramic coatings, nanostructured electromagnetic interference shielding materials, and composites consisting of carbon fibers coated by pyrolytic carbon placed in a different ceramic matrix (e.g. SiC). Five graduate students from the US and Germany and two-to-four undergraduate students from UNH are educated in a collaborative, international setting. Each of them will impact their peers and colleagues with their experience.
