Gelcasting: From laboratory development toward industrial production

Omatete, Ogbemi O.; Janney,; Nunn, Stephen D.

doi:10.2172/215834

Cited by 87 publications

(121 citation statements)

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“…Particle size distribution was determined using a laser granulometer (Fristch Analysette 22). Then, the precursor of the second phase, a 3M ZrCl 4 (Fluka, > 98% purity) aqueous solution, is drop-wise added to the alumina slurry to obtain the AZ composite powder. The amount of ZrCl 4 was calculated assuming that zirconia was fully tetragonal in the final composites, so that a α-Al 2 O 3 to ZrCl 4 weight ratio of 1:0.636 was employed.…”

Section: Methodsmentioning

confidence: 99%

“…It is important, in this process, to have as high as possible solids loading in the slurry to minimize shrinkage and warpage during drying and to enhance fired density. At the same time, it is necessary that the suspension remains fluid and pourable [4]. For this reason, the viscosity of the ceramic slurries at 60°C was measured using a viscometer (Brookfield HBDV-II), before and after the agar addition.…”

Section: Methodsmentioning

confidence: 99%

“…Next, the ceramic powder is dispersed in the premix solution and then cast in a nonporous mold. As in other slip processes, efficient deairing of the slip and careful mold filling are required to avoid the introduction of defects that may limit the strength and other physical properties [4]. By the action of temperature or/and chemical cross-linking reactions, the gel-formers create a strong polymer hydrogel, which permanently immobilizes the ceramic particles in the desired shape of the mold cavity.…”

Section: Introductionmentioning

confidence: 99%

“…Gelcast green bodies have a high strength, allowing them to be easily machined before sintering [5]. Moreover, the complexity of the shapes obtainable by gelcasting is limited only by the ability to design and fabricate the molds [4].…”

Section: Introductionmentioning

confidence: 99%

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Development and mechanical characterization of novel ceramic foams fabricated by gel-casting

Tulliani

Lombardi

Palmero

et al. 2013

Journal of the European Ceramic Society

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Porous ceramic materials are of considerable interest for a variety of chemical and industrial applications in extremely harsh conditions, particularly at very high temperatures for long times. A modified gelcasting process employing agar as a natural gelling agent and polyethylene spheres as pore formers was exploited to produce porous ceramic bodies. Alumina and alumina-ZrO 2 (AZ) powders were used to prepare samples having a porosity of about 65-70-75 vol%. The composite powder was produced by a surface modification route, i.e. by coating a well dispersed alphaalumina powder with a zirconium chloride aqueous solution. Upon thermal treatment, ultra-fine tetragonal zirconia grains formed on the surface of the alumina particles. SEM observations and image analysis were used to characterize the microstructure of porous samples and uniaxial compressive tests were used to measure their mechanical behavior.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Development and mechanical characterization of novel ceramic foams fabricated by gel-casting

Tulliani

Lombardi

Palmero

et al. 2013

Journal of the European Ceramic Society

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“…[ 1,2] The technique can be employed for a diverse group of materials to produce both monolithic and composite ceramic components. In this processing method, a ceramic powder is mixed with an organic monomer in solution.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Resonance Imaging of Gel-Cast Ceramic Composites

Dieckman

Balss

Jendrzejczyk

et al.

Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures—B: Ceramic Engineering An

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Fast Consolidation in Aqueous Tape Casting through Alginate Gelation

et al. 2001

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Tape casting is a well-established technology for manufacturing flat, materials of large surface area used in various applications. [1,2] The main market is in the electronics industry, where tape casting is used to produce thin and thick film circuitry, capacitors, solid oxide fuel cells, etc. In this technique a concentrated suspension is prepared and spread onto a carrier film by a blade that gives the desired thickness. Tape-casting suspensions are mostly prepared in non-aqueous solvents [3] in order to allow quick drying and peel out. In addition to deflocculants, binders and plasticizers are required to provide the consistency and flexibility necessary for handling. [4,5] In the last few years an interest in aqueous tape casting has arisen because of the obvious cost, health, and environmental benefits of using water. [6±8] However, aqueous tape casting has important drawbacks, such as the low evaporation rate in comparison to non-aqueous suspensions. Furthermore, the evaporation rate of water depends on the solid loading of the suspension. Higher solid loadings lead to smaller pore channels for evaporation of water. Therefore, evaporation rates are expected to decrease with increasing concentration of particles. The higher retention of water (i.e., longer drying times) makes differential shrinkage occur, thus leading to crack formation. The drying kinetics of waterbased tape-casting slips has been studied to improve the quality of the final tapes. [9] In the shape forming of bulk parts in ceramic processing there is a focus on gelling technologies, in which a polymer dissolved in the suspension is forced to gel in response to a temperature change or a chemical polymerization. The most frequent case is that of thermal gelation, [10±12] in which a polysaccharide (such as agar, agarose, or carrageenan) gels on cooling below the glass transition temperature (T g ). Chemical gelation has been used for shaping complex parts from suspensions containing monomers that polymerize in the presence of activators and initiators, as in the so-called gelcasting method. [13] On the other hand, gelation has been used in a new group of shaping methods, [14] such as the solid free-form, 3D-printing, etc., in which a complex shaped piece is constructed by depositing droplets of the suspension containing binders that polymerize through a chemical gelation process. [15] The deposition of small drops of suspension is made step-by-step, thus requiring long forming times and limiting the final size of the piece.Considering these two technologies our objective is to combine them for producing large surface ceramic tapes in water that could gelate in order to allow the peel out immediately after casting while maintaining a sufficient consistency for handling. This should prevent crack formation, as the cast tape and the carrier substrate are not in contact during drying. For this purpose thermal gelation is not recommended because of the complexity of the system and the difficulties of maintaining the desired temperature in the d...

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Gelcasting: From laboratory development toward industrial production

Cited by 87 publications

References 0 publications

Development and mechanical characterization of novel ceramic foams fabricated by gel-casting

Development and mechanical characterization of novel ceramic foams fabricated by gel-casting

Magnetic Resonance Imaging of Gel-Cast Ceramic Composites

Fast Consolidation in Aqueous Tape Casting through Alginate Gelation

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