Processing of porous alumina by foaming method-effect of foaming agent, solid loading and binder

Soumya, Devavarapu; Chaudhuri, Paritosh; Shrivastava, Aroh; Bhattacharyya, Santanu

doi:10.1016/j.ceramint.2019.03.139

Cited by 11 publications

(4 citation statements)

References 31 publications

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“…Fukushima's research group has conducted several studies [2,[14][15][16][17][18][19][20][21] focused on the manufacture of high porosity materials through freeze-casting. In 2018, Tang et al [22][23][24][25][26] also turned their researches to the method, and in 2019, several authors [27][28][29][30][31][32][33][34] reported studies involving freeze-casting to obtain materials with high porosity and morphological pore control. Therefore, this scientific field is in continuous growth, and studies that improve the method are published even today.…”

Section: Introductionmentioning

confidence: 99%

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Freeze-casting applied to ceramic materials: a short review of the influence of processing parameters

et al. 2021

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In recent years there is a high interest in the freeze-casting process because it is a simple, economical, and environmentally friendly method for obtaining highly porous materials. Most of the materials obtained by this technique have directional pore structure and anisotropic properties. However, a wide range of pore size and morphology can be obtained by the control of processing parameters, such as solvent type, solids concentration, particle size, freezing rate, and types of additives. The varied morphologies permit the application of freeze-casted materials in various technological applications. However, despite the high amount of studies about freeze-casting of ceramic materials in the last years, review articles addressing the influence of processing parameters on the pore characteristics of obtained ceramics are still scanty. Therefore, this review addresses the influence of freeze-casting process parameters on the pore characteristics of the ceramic materials.

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Section: Introductionmentioning

confidence: 99%

“…Relationship between porosity and the amount of solids in the suspension for freeze-cast ceramics[8,27,54,[57][58][59][60][61][62].…”

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confidence: 99%

Freeze-casting applied to ceramic materials: a short review of the influence of processing parameters

et al. 2021

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“…However, porous ceramics have recently gained considerable interest. Cellular ceramics represent a class of lightweight inorganic materials with versatile performance due to a combination of ceramic and porous structures 1 . Porous ceramics possess intriguing properties, such as low density, high specific strength, high permeability, high surface area, low specific heat, high refractoriness, excellent chemical and mechanical resistance, low thermal conductivity, and biocompatibility 2,3 .…”

Section: Introductionmentioning

confidence: 99%

Alumina dissolution process to fabricate bimodal pore architecture alumina with superior green and sintered properties

2023

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Herein, a straightforward, adaptable, and cost‐effective approach has been proposed to realize the concept of dissolution of alumina in acidic aqueous media to fabricate porous alumina showing exceptional green machining properties and exhibiting good thermomechanical properties through in situ generated blowing agents and thermo‐foaming process. The process involves dissolving alumina in concentrated sulfuric acid to generate aluminum hydroxide and aluminum sulfate, which act as blowing agents to produce pores in the final structure through a decomposition process at elevated temperatures. By varying the concentration of deionized water and acidification using sulfuric acid, different alumina slurries are prepared. Sintering shrinkage is well countered through simultaneous consolidation and decomposition process during the heat treatment, and a minimum shrinkage of 0.88% is achieved. In addition to its pore‐forming properties, aluminum sulfate also provides strong binding effects to green bodies, contributing to their exceptional green machining properties. The resulting porous alumina exhibits a green flexural strength of up to 17 MPa, making it capable of bearing loads and forces during green machining. The sintered porous alumina fabricated in the study has a porosity range of 34.43%–59.24% and a flexural strength of 27.84–53.21 MPa. The prepared porous alumina also exhibits satisfactory thermal resistivity, with a minimum thermal conductivity of 1.23 W/m K, and has intra/intergranular space in the nano range. The coexistence of a combination of bimodal pores in a single monolithic matrix makes it exceptionally porous and suitable for an extensive spectrum of applications.

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“…At the total porosity of 65%, the porous materials exhibited a compressive strength of 9.18 MPa. In order to attain the closed pores, it has been reported that a slurry or solution of ceramic precursors and sacri cial agents should be formed [26,[33][34][35][36]. Porous alumina with high closed porosity was fabricated by gel-casting of Al 2 O 3 powder and polyethylene, subsequently sintering at 1400 o C for 1h [37].…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of Undoped and Chromia-Doped Porous Alumina Using Different-Sized Particles

Nguyen

Nanko

et al. 2021

Preprint

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Highly porous alumina (Al2O3) was prepared by sintering of Al2O3 powder using ammonia bicarbonate (NH4HCO3) as a pore-forming agent and chromia (Cr2O3) as a sintering additive. In order to investigate the influence of particle shape and size on the characterization of sintered porous Al2O3, the starting Al2O3 powders included commercial disk micro-sized powder and synthesized spherical nanopowder. The nanoscale Al2O3 powder was produced via combustion synthesis route. At the optimal pore-forming agent concentration, the porous Al2O3 sintered by nanoparticles had a smaller pore size and a lower total porosity than the one prepared by microparticles. The differences of open porosity and closed porosity between porous Al2O3 synthesized by micro and nano-scale powders with and without Cr2O3 dopant were also discussed. In addition, the compressive strength of porous Al2O3 achieved by nano-sized powders, especially with Cr2O3 dopant, had a higher value in comparison with the one prepared by micro-sized powders.

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Processing of porous alumina by foaming method-effect of foaming agent, solid loading and binder

Cited by 11 publications

References 31 publications

Freeze-casting applied to ceramic materials: a short review of the influence of processing parameters

Freeze-casting applied to ceramic materials: a short review of the influence of processing parameters

Alumina dissolution process to fabricate bimodal pore architecture alumina with superior green and sintered properties

Preparation and Characterization of Undoped and Chromia-Doped Porous Alumina Using Different-Sized Particles

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