Inter-American Materials Collaboration (CIAM): A Novel Synthesis and Sintering Process for Nanostructured Oxide and Carbide Ceramic Composites

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Non-technical Description:This project is jointly funded by the Division of Materials Research (DMR) and the Office of International Science and Engineering (OISE). It will provide experimental and computer-modeling experience to students and high school teachers in the preparation of advanced nanostructured composite materials. The uniqueness of the process that will be applied for the formation of these composites lies in its capacity to prepare extremely fine starting powders, and to consolidate the powders into useful engineering components using lower temperatures and lower pressures. The lower temperatures and pressures prevent exaggerated growth of the powders. Hence, the nanostructured character of the composites can be preserved with beneficial engineering implications. With such a structure, these composite materials are hypothesized to possess unique mechanical properties, which may prove useful in engineering applications, particularly in the aerospace industry, where the need for stronger and lighter composite materials is always present. Through this project, students from the participating institutions will be trained in experimental techniques and computer models that will allow the synthesis and sintering of unique materials. In addition, teachers from a local high school will be involved in research activities and development of lesson plans during the summer at the lead institution.Technical Details:The objective of this project is to study the unique synthesis and spark-plasma sintering (SPS) of fully-densified oxide and carbide nanocomposites. The first activity to be undertaken will be the synthesis of nanostructured powders using a reverse micelle process, and the characterization of the process over a wide range of experimental conditions (i.e., temperature of calcination, time of calcination, and water-to-surfactant ratio) in order to optimize and scale-up the process. As a complement to the experimental work, computer models for the synthesis process will be developed that can be used to predict the final shape, particle size, and crystallite size of the powders being prepared. Subsequently, densification of the nanostructured powders via spark-plasma sintering will be undertaken and characterized over a wide range of experimental conditions (i.e., pressure, temperature, and time of densification). The microstructural development during the densification process will be examined carefully to determine grain growth of the nanopowders. The project will distinguish itself from previous experimental studies in three ways: (1) this will be first study that will use ultra-fine oxide and carbide powders (in the 1 - 5 nm range) for sintering via SPS to obtain compacts with grain sizes 30 nm and lower; (2) this will be the first study that will utilize a mesoscopic approach for the development of a computer model of reverse micellar systems, which is of great value for capturing many molecular-type features that are not possible using continuum mechanics approaches or fully atomistic models, the latter due to computational restrictions; and (3) this will be the first study that will characterize fully dense nanostructured compacts with grain sizes below 30 nm, which will allow the determination of mechanical properties in these types of materials.