This research program, co-funded between the Division of Materials Research and the Office of International Science and Engineering, will focus on relationship between synthesis, structure and properties of diamond-silicon carbide (SiC)composites. Diamond-based composites manufactured under high-pressure and high-temperature conditions are characterized by high hardness and very good wear resistance. How the structure and properties of the composites are influenced by inclusion of nanosize diamonds in the production protocol will be examined. Superhard diamond composites can be applied by many industries; one possible application is in oil and gas exploration where diamond composites could be used as cutting inserts in drill bits. An increase in the lifetime of drill bits will lower the cost of gas/oil drilling wells. It is difficult to assign the monetary value to the diminished risk of environmental pollution during potential blowouts by reduced frequency of drill bits replacements, but it would be substantial. This project is being carried out in collaborations with Eotvos University, Budapest, Hungary and High Pressure Research Center of Polish Academy of Sciences, Warsaw, Poland. Students will visit these institutions for extended periods of time and work under supervision of the leading Hungarian and Polish scientists. Likewise, Hungarian and Polish scientists will visit TCU and conduct high-pressure experiments at national laboratories. TECHNICAL DETAILS: The microstructure of composites can be described by characterizing diamond and silicon carbide phases in terms of their crystallite size and size distribution, and lattice strain caused by crystal defects. The most likely defects are stacking faults and interfaces between the crystallites. The emphasis is on understanding the formation mechanism of the nanostructured silicon carbide matrix, its structural and mechanical stability, and on characterization of its mechanical and physical properties. This combined approach will guide in selection of the optimum preparation procedures of precursors and technological conditions leading to sintering of superhard diamond-SiC nanocomposites. Novel methodologies of defects characterization, determination of grain sizes and atomic structure of nanocrystals from x-ray and neutron diffractograms, will be further developed and refined, and applied to characterize nanomaterials. When developed they could be used to characterize other metal, dielectric, or semiconductor nanocrystals and nanocomposites. Specifically, examination of the structures formed at the crystallite surfaces/interfaces will enable assessing chemical reactivity of these materials, and the structure of grain boundaries in nanostructured matrix and its relation to the material properties. Fundamental understanding of the atomic arrangements in nanosize crystals, especially near the interface, is absolutely necessary for further progress in nanotechnology. Supplementary information on structure of composites will be obtained from other techniques. The interdisciplinary nature of the nanotechnology-related research and proposed education activities will prepare students and young professionals for future challenges. International collaboration, integration of research activities, sharing of knowledge and practical know-how, the exchange of graduate students and post-doctoral fellows, and series of lectures offered by visiting senior researchers will offer students a new educational experience.
