Multiscale modeling ceramics

The recent growth of multiscale modeling has permeated every material type known to mankind regarding structural members. Although most of the work has been focused on metal alloys as they have been used the most over time as reliable structural materials, multiscale modeling has also been employed for ceramics and polymer systems (both synthetic and biological). 

J.C. Mauro, A.K. Varshneya Multiscale modeling of GeSe2 glass structure. J. Amer. Ceramic Soc. 89, 2323-2326 (2006)... 

For each phenomenon, there are also many elements involved which determine the behaviour of each phenomenon. These phenomena are described by a wide range of characteristic time and length values. For the case of CVI fabrication of fibre-reinforced ceramic-matrix composites, the diameter of a molecule and the thickness of the interfacial phase are about 10 1 run and 102nm respectively, whilst the sizes of the substrate/component and the reaction are around 1 m. In addition, elementary chemical reactions occur in a time range of 10 " to 10 4 s, the time for heat transfer and mass transfer is around 1 s to 10 min. By contrast, the total densification time for one CVI run is as long as approximately 102 h. In such cases, it is necessary to establish multiscale models to understand and optimise a CVD process. 

He, Y., and Fan, J. 2005. Multiscale modeling methodology for layered composites of polymer-ferroelectric ceramics. Journal of Intelligent Material Systems and Structures 16 603. 

Kinetic Monte Carlo and hyperdynamics methods have yet to be applied to processes involved in thermal barrier coating failure or even simpler model metal-ceramic or ceramic-ceramic interface degradation as a function of time. A hindrance to their application is lack of a clear consensus on how to describe the interatomic interactions by an analytic potential function. If instead, for lack of an analytic potential, one must resort to full-blown density functional theory to calculate the interatomic forces, this will become the bottleneck that will limit the size and complexity of systems one may examine, even with multiscale methods. 

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