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Published August 15, 2021 | public
Journal Article Open

Coarsening of dendrites in solution-based freeze-cast ceramic systems


The morphologies of freeze-cast materials are typically controlled and tuned by adjusting the freezing front velocity and temperature gradient. Recently it has been demonstrated that coarsening, similar to that commonly practiced in alloy systems, is also effective for morphological control in freeze-cast materials. However, the underlying coarsening mechanisms and their effect on microstructure evolution are largely unknown. In this study, frozen preceramic polymer/cyclohexane solutions were coarsened at 2 °C and 4 °C for up to 5 h, and the resulting morphologies were characterized using scanning electron microscopy, mercury intrusion porosimetry, and X-ray computed tomography. During coarsening the microstructure evolved from dendritic (primary and secondary pores) to honeycomb-like (large open channels with flat walls). The size of both primary and secondary pores increased linearly with the cube root of coarsening time, consistent with dendritic coarsening in alloy systems. Other important metrics such as primary dendrite spacing, dendrite growth directionality, and the effect of coarsening on the pore-ceramic interface area are reported. These findings provide novel insights into coarsening of freeze-cast systems and can lead to new avenues for microstructure tailorability.

Additional Information

© 2021 Acta Materialia Inc. Published by Elsevier. Received 23 March 2021, Revised 21 May 2021, Accepted 27 May 2021, Available online 2 June 2021. These studies were supported by the U.S. National Science Foundation under CBET-1911972 (NA, KTF), the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD) under award number 70NANB19H005 (TS), the National Aeronautics and Space Administration under NNX16AR13G (PWV), and the U.S. Army Research Office Young Investigator Program under W911NF-18-1-0162 (AJS). NSM and AJS acknowledge the University of Michigan College of Engineering for financial support and the Michigan Center for Materials Characterization for use of the instruments and staff assistance. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


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August 22, 2023
September 21, 2023