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Bao, Xujin; Nangrejo, M.; Edirisinghe, Mohan

doi:10.1023/a:1004805023228

Cited by 73 publications

(21 citation statements)

References 15 publications

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“…The advantages include a very wide range of pore (cell) sizes (typically 1 mm to 2 mm), well-defined open-cell structures and macro-defect-free struts. [165][166][167][168] Paper-based template has been also proposed; Travitzk et al 169 succeeded in fabricating single-sheet, corrugated structures, and multilayer ceramics by using various paper replica templates. Unique micro-structures such as aligned pores derived from fibres in the paper, elongated morphology and multilayer stacking were observed, and they substantially affected the anisotropic mechanical properties.…”

Section: Replica Templatesmentioning

confidence: 99%

Macro-porous ceramics: processing and properties

Ohji

Fukushima

2012

International Materials Reviews

609

319

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Porous ceramics are now expected to be used for a wide variety of industrial applications from filtration, absorption, catalysts and catalyst supports to lightweight structural components. During the last decade, tremendous efforts have been devoted for the researches on innovative processing technologies of porous ceramics, resulting in better control of the porous structures and substantial improvements of the properties. This article intends to review these recent progresses of porous ceramics. Because of a vast amount of research works reported in this field these days, the review mainly focuses on macro-porous ceramics whose pore size is larger than 50 nm. Followed by giving a general classification of porous ceramics, a number of innovative processing routes developed for critical control of pores are described, along with some important properties. The processes are divided into four categories including (i) partial sintering, (ii) sacrificial fugitives, (iii) replica templates and (iv) direct foaming. The partial sintering, the most conventional technique for making porous ceramics, has been substantially sophisticated in recent years. Very homogeneous porous ceramics with extremely narrow size distribution have been successfully prepared through sintering combined with in situ chemical synthesis. Carefully tailored micro-structure (size, morphology and orientation of grains and pores, etc.) of porous ceramics has led to unique mechanical properties, which cannot be attained even in the dense materials. Various types of the sacrificial fugitives have been examined for obtaining well-tuned shape and size of pores. The freeze-drying techniques using water or liquid as fugitive materials have been most frequently studied in recent years. Controlling growth of ice during freezing has led to unique porous structures and excellent performances of porous ceramics, e.g. excellent mechanical behaviour for highly porous lamellar hydroxyl-apatite scaffolds. Numerous approaches on the replica templates have been developed in order to produce highly porous ceramics having interconnected large pores and sufficiently strong struts without cracks. Natural template approaches using wood, for example, as positive replica, have been intensively studied in these years and have realised highly oriented porous open-porous structure with a wide range of porosity. As for the direct foaming technique, a variety of novel techniques which stabilise the bubbles in ceramic suspension have been developed to suppress large pore formation, e.g. evaporation of emulsified alkane droplets and use of surface-modified particles. We also briefly review porous ceramics with hierarchical porosity (incorporation of macro-, meso-and micropores), which have attracted much attention in both academic and industrial fields. Finally the article gives the summary and discusses the issues to be solved for further activating the potential of porous ceramics and for expanding their applicability.

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Section: Replica Templatesmentioning

confidence: 99%

Macro-porous ceramics: processing and properties

Ohji

Fukushima

2012

International Materials Reviews

609

319

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“…Inspired by the early work of Schwartzwalder and Somers [2], many investigations explored the usage of several templates such as wood [52,53], coral [54,55], polymeric foams [56][57][58][59], etc, to prepare porous ceramics for use in a variety of applications [5]. The porous ceramics prepared from polymeric foams and ceramic slurries possess thin struts containing central holes [58].…”

Section: Replicamentioning

confidence: 99%

“…The porous ceramics prepared from polymeric foams and ceramic slurries possess thin struts containing central holes [58]. Edirsinghe and co-workers developed a simple method where polysilane solution was substituted for the ceramic slurry to produce porous SiC ceramics with improved strength [56][57][58][59]. The polysilanes were dissolved in dichloromethane to form polymeric precursor solutions in which a PU sponge was immersed to form pre-foams.…”

Section: Replicamentioning

confidence: 99%

“…The essential steps in the foam-ceramic slurry method, namely removal of excess ceramic slurry from polymeric sponge and evaporation of volatile slurry after drying, are not required in the foam-polymeric precursor method [56][57][58][59]. In contrast to ceramic suspension-derived reticulated structures, porous ceramics obtained from preceramic polymers contain homogeneous microstructures with crack-free struts due to the improved wetting of the sponge and/or partial melting of the cross-linked polymers during pyrolysis [56][57][58][59].…”

Section: Replicamentioning

confidence: 99%

“…Furthermore, shrinkage can be controlled by varying the concentration of polysilanes in the precursor solutions [57][58][59][60] and/or second phase [56]. It is possible that the expansion and gas evolution of the polymer during heating lead to the significant stresses that can cause macroscopic cracks on the resultant ceramic struts.…”

Section: Replicamentioning

confidence: 99%

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Processing of polysiloxane-derived porous ceramics: a review

Kumar

Kim

2010

Science and Technology of Advanced Materials

111

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Because of the unique combination of their attractive properties, porous ceramics are considered as candidate materials for several engineering applications. The production of porous ceramics from polysiloxane precursors offers advantages in terms of simple processing methodology, low processing cost, and easy control over porosity and other properties of the resultant ceramics. Therefore, considerable research has been conducted to produce various Si(O)C-based ceramics from polysiloxane precursors by employing different processing strategies. The complete potential of these materials can only be achieved when properties are tailored for a specific application, whereas the control over these properties is highly dependent on the processing route. This review deals with processing strategies of polysiloxane-derived porous ceramics. The essential features of processing strategies-replica, sacrificial template, direct foaming and reaction techniques-are explained and the available literature reports are thoroughly reviewed with particular regard to the critical issues that affect pore characteristics. A short note on the cross-linking methods of polysiloxanes is also provided. The potential of each processing strategy on porosity and strength of the resultant SiC or SiOC ceramics is outlined.

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Polysiloxanes & PolysilanesBased in part on the article Polysiloxanes & Polysilanes by Robert West which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Mitra

Atwood

2005

Encyclopedia of Inorganic Chemistry

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Silicon‐containing polymers, of which polysiloxanes and polysilanes are the most important ones, are becoming more and more important industrially because of their unique properties. Polysiloxanes that contain SiOSi linkage in their structure are most commonly prepared by ring‐opening polymerization of cyclic siloxanes. The monomer for this process is prepared by the ‘Direct Process’. The polysiloxanes are hydrophobic despite having polar SiO bonds in their structures. They possess highly flexible structures with large SiOSi bond angles. They are chemically inert and have good thermal stability, low viscosity, and good gas permeability. These polymers and related copolymers find use in a variety of fields as silicone fluids, elastomers, and resins. Polysilanes consisting of chains exclusively made up of silicon atoms are most commonly prepared by Wurtz coupling reaction. through sodium condensation of dichlorosilanes. The most interesting aspect of their properties is σ‐electron delocalization, which gives rise to many interesting photochemical and photophysical effects like thermochromism, solvatochromism, and ionochromism. These polymers find use in preparation of silicon carbide and as photoresists, photoinitiators, and hole conductors in electrophotography. In this article, the history, synthesis, properties, and application of polysiloxane and polysilane polymers have been reviewed.

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Untitled

Cited by 73 publications

References 15 publications

Macro-porous ceramics: processing and properties

Macro-porous ceramics: processing and properties

Processing of polysiloxane-derived porous ceramics: a review

Polysiloxanes & PolysilanesBased in part on the article Polysiloxanes & Polysilanes by Robert West which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

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