SINTER MODELING FOR IMPROVED CERAMIC PROCESSING AND PERFORMANCE Sandia National Laboratories is developing an "integral approach to the science of sintering". Development is aimed at simulating the entire sintering process, including diffusion by various mechanisms, early stage sintering, and sintering of multi-phase systems. The Sandia program uses proprietary research codes that can be modified for application to a variety of microstructural evolution problems and the knowledge and experience to simulate a wide range of ceramic processes and behavior. These microstructural-based codes are being developed to help predict engineering and electrical properties of ceramics and have currently been applied to projects that focus on the evolution of microstructure when it is coupled to applied stress or strain. Examples of code applications are grain growth, Ostwald ripening, diffusion, dynamic temperature profiles, etc. Current capabilities include modeling of isotropic and non-isotropic Ostwald ripening in 2- and 3-D, grain growth in single- & multi-phase systems with pinning under isothermal and non-linear dynamic temperatures, and pore migration and coalescence during final stage sintering. This effort is being combined with experimental techniques to monitor densification for model validation. Novel experimental approaches developed at Sandia are particularly well suited to characterizing thick-film and thin-film sintering. Applications Engineering ceramics which require tailoring of microstructure for optimal performance. These materials include structural, optical and electrical ceramics, ceramics filters, ceramic coating, etc. Complex multi-phase ceramics such as multilayered electronic substrates would benefit from these expertises. Potential Benefits Reduce process development time and cost for new product development. Improve design of components by tailoring microstructures for specialized applications. Sandia National Laboratories can work with experimentalists to understand, model, predict and develop processing parameters that optimize microstructurefor various applications, relationships between microstructural features and performance, and evolution of microstructure during use which in turn effects component performance. Demonstrated Achievements Successfully predicted kinetics and grain size distribution of Ostwald ripened systems at high solid fraction. Predicted grain elongation during directed laser-melt processing. Modeled the coarsening and pore migration in UO2 fuel rods. Predicted grain size distribution in final stage sintering at different grain growth to densification rates. References Numerous publications (available upon request) on simulation of microstructural evolution. Collaborations with academia which enhance our simulation capability. Organized symposia on modeling of ceramic processing and behavior. Edited an issue of the Journal of ACerS on modeling ceramics. Sandia is interested in partnering with industry to further develop reliability and failure analysis of glass and ceramic components. Companies interested in partnering with Sandia should be willing to sponsor a collaborative project via a Cooperative Research and Development Agreement (CRADA) with Sandia. For further information please respond by mail or fax to Sheila Pounds by June 30, 1999 at Sandia National Laboratories, MS-1380, P. O. Box 5800, Albuquerque, New Mexico 87185-1380. Fax: (505) 843-4163. Please indicate the date and title of this CBD notice. E-MAIL: Sheila L. Pounds, slpound@sandia.gov. Posted 06/16/99 (W-SN343794).

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