Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Poster Session
MM 17.34: Poster
Montag, 26. März 2012, 17:00–19:00, Poster B
Investigation of freeze casting at the microscopic scale — •Marcel Huber1, Frank Wendler2, and Britta Nestler1,2 — 1IAM-ZBS, Karlsruhe Institute of Technology — 2IAM-ZBS, Karlsruhe University of Applied Science
Motivated by freeze casting, an established process to produce ceramic materials with an open pore structure, we study ice crystal growth by using a phase-field model of Allen-Cahn type. The representation of each ice-crystal of different orientation and the liquid is defined by introducing non-conserved order parameters. The solid/liquid interfaces evolve due to an interplay of a driving force and of interface anisotropies with a normal velocity depending on a chemical potential, kinetic coefficient and surface stiffness. We present an anisotropy formulation for interface energies and kinetics suitable for ice-crystallization by a combination of selected spherical harmonics. We introduce an efficient numerical method based on the definition of appropriate boundary conditions to solve the dynamics of the thermal field. We show the dendritic growth shapes and evaluate the tip velocities. We investigate the solidification of ice in a pure water-ice system where water freezes by cooling from one side (cooling plate). By changing the temperature gradient, we evaluate the velocity of the solid/liquid interfaces and compare our results with experimental observations. With regard to the freeze casting process, we analyse the freezing process in a water system filled with inert particles. In simulations, we study the interaction of the particles with the growing ice front and among each other.