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Fukasawa, Tomonori; Deng, Zhen‐Yan; Ando, Motohide; Ohji, Tatsuki; Gotô, Yasuhiro

doi:10.1023/a:1017946518955

Cited by 199 publications

(62 citation statements)

References 4 publications

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“…The technique consists of freezing a liquid suspension (aqueous or not), followed by sublimation of the frozen phase and subsequent sintering, leading to a porous structure with unidirectional channels in the case of unidirectional freezing, where pores are a replica of the ice crystals [2] (in case of aqueous slurries). Although applied to a wide variety of materials so far, like alumina [11,12], hydroxyapatite [13], silicon nitride [14], NiO-YSZ [15], or polymeric materials [16], a proper and rational control of the microstructure morphology has not yet been achieved.…”

Section: Introductionmentioning

confidence: 99%

Ice-templated porous alumina structures

2007

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The formation of regular patterns is a common feature of many solidification processes involving cast materials. We describe here how regular patterns can be obtained in porous alumina by controlling the freezing of ceramic slurries followed by subsequent ice sublimation and sintering, leading to multilayered porous alumina structures with homogeneous and well-defined architecture. We discuss the relationships between the experimental results, the physics of ice and the interaction between inert particles and the solidification front during directional freezing. The anisotropic interface kinetics of ice leads to numerous specific morphologies features in the structure. The structures obtained here could have numerous applications including ceramic filters, biomaterials, and could be the basis for dense multilayered composites after infiltration with a selected second phase.

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Section: Introductionmentioning

confidence: 99%

Ice-templated porous alumina structures

2007

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“…Here we apply this natural concept of hierarchical design to ceramic/polymer (Al 2 O 3 /PMMA) hybrid materials which we are able to fabricate in bulk form by freeze casting (20)(21)(22)(23)(24). Using controlled freezing of ceramic-based suspensions in water, we are able to form large porous ceramic scaffolds ( Fig.…”

mentioning

confidence: 99%

Tough, Bio-Inspired Hybrid Materials

Munch

Launey

Alsem

et al. 2008

Science

1,583

1,238

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The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs extremely difficult to replicate synthetically. Here we emulate Nature's toughening mechanisms through the combination of two ordinary compounds, aluminum oxide and polymethylmethacrylate, into ice-templated structures whose toughness can be over 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic material whose high yield strength and fracture toughness (~200 MPa and ~30 MPa√m) provide specific properties comparable to aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.With the quest for more efficient energy-related technologies, there is an imperative to develop lightweight, high-performance structural materials that possess both exceptional strength and toughness. Unfortunately, these two properties tend to be mutually exclusive and the attainment of optimal mechanical performance is invariably a compromise often achieved through the empirical design of microstructures. Nature has long developed the ability to combine brittle minerals and organic molecules into hybrid composites with exceptional fracture resistance and structural capabilities (1-3); indeed, many natural materials like bone, wood and nacre (abalone shell) have highly sophisticated structures with complex hierarchical designs whose properties are far in excess what could be expected from a simple mixture of their components (2,4). Biological mineralized composites, in particular bone, dentin and nacre (5-7), can generate fracture toughness (i.e., resistance to the initiation and growth of a crack) primarily by extrinsic toughening mechanisms (8) that "shield" any crack from the applied loads. These mechanisms, which are quite different to those that toughen metals for

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“…[4][5][6][7] This method has also been examined in functional ceramics, but not in ceramic/metal composites. In this study, ceramic forms with various characteristics can be successfully fabricated by the freezedry process with water-based polymer/alumina slurry (gelate-freezing process).…”

Section: Fabrication Of Porous Ceramic By the Gelate-freezingmentioning

confidence: 99%

Effect of Internal Structure on Thermal Properties of Alumina/Aluminum Composites Fabricated by Gelate-Freezing and Partial-Sintering Process, Respectively

Nakata

Suganuma

2005

Mater. Trans.

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The purpose of the present work was to clarify the effects of parameters of porous ceramics on the characteristics of composites fabricated by high-pressure infiltration. Alumina with different porosity (15-70 vol%) and pore morphology was successfully fabricated by gelate-freezing and the partial-sintering, respectively. Alumina/aluminum composites were made by squeeze casting, the aluminum into the alumina sintered bodies. By evaluating the coefficient of thermal expansion (CTE) and thermal conductivity of the composites, it became obvious that variation in the structure and fraction of porous alumina sintered bodies influenced CTE, but not thermal conductivity.

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Untitled

Cited by 199 publications

References 4 publications

Ice-templated porous alumina structures

Ice-templated porous alumina structures

Tough, Bio-Inspired Hybrid Materials

Effect of Internal Structure on Thermal Properties of Alumina/Aluminum Composites Fabricated by Gelate-Freezing and Partial-Sintering Process, Respectively

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