Cellular Ceramics / remarks

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Concluding Remarks

Michael Scheffler and Paolo Colombo

We try here to briefly summarize and give an outlook concerning the future of this fascinating field of cellular ceramics, based on our knowledge of the published literature and several discussions that we had in the period between the conception of the book (summer 2003) and its release (spring 2005) with specialists at the forefront of research and development. As in many technical evolutions the need for new applications will affect processing technologies. Novel processing technologies lead to new structures and advanced properties and this in turn stimulates conceiving novel, broader applications. A deeper understanding of the structure–properties relationship with the aim of producing components with improved reliability can also be achieved by employing novel characterization and modeling tools. In this context the following developments can be expected in the coming years:

Processing and applications of cellular ceramics – foams, honeycombs, fibers, hollow-sphere assemblages, 3D periodic structures – will be a major topic. Main efforts will be:

Cellular Ceramics: Structure, Manufacturing, Properties and Applications.

Michael Scheffler, Paolo Colombo (Eds.)

Copyright 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

ISBN: 3-527-31320-6

622 Concluding Remarks

. Foams and honeycombs in environmental technology. While honeycomb-sup- ported catalysts have already become one of the most widespread technical solutions for exhaust gas cleaning (also in stationary applications), ceramic foams and fiber mats are being developed and tested as well for this purpose. In future there will be more applications for cellular ceramics in environmentally benign processes.

. Bottom-up manufacturing. Besides honeycombs and foams produced by wellestablished industrial processes, periodic structures and tailor-made structures fabricated by bottom-up processing technologies (inkjet printing, robocasting, fused deposition) will become a major topic in the ceramic and processing area, because they allow components to be fabricated with a very well controlled morphology and their dimensions to be reduced to the nanoscale. Main applications will be found in exhaust gas cleaning (catalyst supports), tissue engineering (artificial bone grafting), and porous preform manufacturing for single parts or small series.

. Monoliths with hierarchical porosity. In heterogeneously catalyzed processes macroporous monoliths with microporous modified surfaces promise to combine excellent fluid dynamics and reaction-adjusted pore diffusion. Modern technologies of surface modification like supported crystallization might allow the tailored production of a broad variety of hierarchically arranged porous materials of all classes of structure (honeycombs and related structures, foams, fiber mats, and periodic structures). The present combination of macro/microporosity will be extended to macro/mesoporosity, and meso/microporosity systems.

. Lightweight technology. An increasing demand for lightweight components for more efficient fuel consumption has been recognized in both the automotive and aerospace industries. The need for ultrahigh-temperature materials in aerospace applications will affect the development of novel lightweight/ highly temperature stable materials and structure combinations. Additional properties, such as impact absorption and sound damping, will lead to more advanced applications for cellular ceramics in these fields.

. UV-transparent glass foams and honeycombs. Cellular ceramics made of UVtransparent materials (silica glass) will play an increasing role in environmental cleaning processes. They provide a greater surface area in comparison to glass tubing when used as support/substrate, and thus increase the efficiency of photocatalytic processes.

Morphology characterisation and modeling of cellular (ceramic) structures will help to understand the structure formation of random cellular materials and lead to novel manufacturing processes resulting in increased structural homogeneity. One of the most promising tools for morphology characterization is X-ray microcomputer tomography. The resolution of common equipment currently allows measurements down to the micrometer range, but the physical limit has not been reached yet. In fact, high-energy synchrotron radiation has already started to be applied to the characterization of microcellular foams. The development of advanced modeling

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tools will allow developers to confidently incorporate cellular ceramics into their design, taking full advantage of their positive characteristics, while at the same time minimizing their weaknesses.

We look forward to the coming years together with the readers and authors of this book, and hope that this work will contribute to developing further worldwide interest in the important field of cellular materials.