Coagulation Kinetics and Mechanical Behavior of Wet Alumina Green Bodies Produced via DCC

Balzer, Beate; Hruschka, Martin K. M.; Gauckler, Ludwig J.

doi:10.1006/jcis.1999.6293

Cited by 84 publications

(114 citation statements)

References 8 publications

Supporting

Mentioning

108

Contrasting

Unclassified

Order By: Relevance

“…Direct Coagulation Casting 7) is an example of a low pressure injection mouldable process using a chemically activated change in solution conditions, changing the particles interaction from repulsive to attractive. This process involves long retention times in the mold to achieve strength enough to unmold the piece.…”

Section: Introductionmentioning

confidence: 99%

Recent trends in shape forming from colloidal processing: A review

Tallón

Franks

2011

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

Shaping ceramic materials is a research area which has continuing innovation and excellence. Dry processing routes gave way to colloidal techniques enabling the preparation of more complex shapes for a wide and growing field of applications. Both dense and porous ceramics with improved properties can be produced. The development of colloidal processing led to the creation of the near-net-shaping concept, performed through slip casting, gelcasting and freeze casting. Even though these concepts have been used for the last few decades, different trends and combinations of these techniques are refreshing the processing strategies in recent years. New chemistries and concepts continue to emerge. This paper creates an overview of the recent trends in near-net-shaping routes, having a deeper look into gelcasting and freeze casting, since both processes are used in the preparation of tailored and custom dense and porous ceramics.

show abstract

Section: Introductionmentioning

confidence: 99%

Recent trends in shape forming from colloidal processing: A review

Tallón

Franks

2011

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

show abstract

“…Direct coagulation casting (DCC) is based on the time-delayed destabilization of a suspension or sol by manipulation and control of the interparticle forces, e.g. via shifting the pH value of a suspension or sol to the isoelectric point (IEP) [9][10][11] . The consolidation mechanisms of the hydrolysis assisted solidification (HAS) are based on the chemical bonding of water by hydrolysis of aluminium nitride (AlN), formation of ammonia and a subsequent precipitation of amorphous and crystalline aluminium hydroxide [12][13][14] .…”

Section: Introductionmentioning

confidence: 99%

Nanoparticle assisted coagulation of aqueous alumina suspensions

Çetinel

Simon

2011

Mat. Res.

View full text Add to dashboard Cite

Colloidal processing of ceramics offers a high potential to achieve homogeneous microstructures with improved material properties. In this study, a novel forming method is investigated, which was already applied successfully for the fabrication of ceramic matrix composites (CMC), but is also considered to be a suitable direct casting technique for the fabrication of advanced ceramics with tailored microstructure and properties. The so-called nanoparticle assisted coagulation method (NPAC) represents a modification of the hydrolysis-assisted solidification (HAS) technique. It promises green components with high green strength, uniform density as well as homogeneous and tailored microstructure. Electrostatically stabilized colloidal suspensions with high solid loadings were produced by dispersing various fractions of submicron alumina powder and aluminium hydroxide nano-powder in water without use of any organic binder. Rheology and coagulation kinetics of suspensions and green part properties were studied regarding to modifications of pH value, setting temperature, amount of setting agent, amount of nano-powder, solids loading and process parameters like ultrasound treatment. It could be revealed that the homogeneous core-shell arrangement of submicron and nanoparticles in the colloidal state can be transmitted to the green state, which improves the microstructure and green density of the green parts. For this, the NPAC method is seen as a promising technique for the fabrication of advanced ceramics with tailored microstructure and properties.

show abstract

“…Una vía importante en este aspecto, es la fabricación de piezas con forma casi final, como es el caso de los procesos de tecnología del producto semifinal o procesamiento inteligente (Near Net Shaping, NNS), en los que el mecanizado que se requiere es mínimo (4). La mayoría de estos métodos se basa en la rápida consolidación de un fluido, transformando una suspensión bien dispersa en un cuerpo rígido, como es el caso de la coagulación directa (DCC) (5), la gelificación (6,7), el conformado por vibración (8), el conformado por capas o fabricación directa de cerámicas (solid free-form, SFF) (9), el conformado inducido por la temperatura (temperatura induced forming, TIF) (10), etc.…”

Section: Introductionunclassified

Nuevas aplicaciones de los alginatos en el conformado cerámico

Santacruz¹,

Nieto²,

Moreno³

2005

Bol. Soc. Esp. Ceram. Vidr.

View full text Add to dashboard Cite

Los alginatos son polisacáridos naturales empleados a menudo en el procesamiento cerámico como ligantes temporales. Sin embargo, además de su función espesante, los alginatos presentan interesantes propiedades como agente gelificante. Esta función ha sido menos explotada en cerámica pero está empezando a recibir gran atención por su versatilidad de cara a nuevas rutas de conformado de piezas y, sobre todo, de láminas y recubrimientos. En este trabajo se revisan los procesos de conformado neto (near-net shaping, NNS) por formación de geles químicos, entre los que se pueden distinguir dos grupos de técnicas, las que emplean monómeros que polimerizan en presencia de un activador y/o catalizador y las que emplean polisacáridos de elevado peso molecular que forman estructuras a través de cationes presentes en el medio. Este trabajo se centra en el último caso y, en particular, se revisa la química de los alginatos, haciendo énfasis en su estructura y en los mecanismos de gelificación y, por último, se evalúan las posibilidades de aplicación de la gelificación química con alginatos en la producción de láminas por la técnica de colaje en cinta, con especial atención a los parámetros que gobiernan el proceso. Palabras clave: Procesamiento, Conformado, Suspensiones, Aditivos de procesamiento, Gelificación química, Alginatos New applications of alginates in the shape forming of ceramicsAlginates are naturally occurring polysaccharides frequently used as temporary binders in ceramic processing. However, behind their thickenning behaviour, alginates have interesting gelling properties. This function has not been exploited in ceramics, although it is receiving increased attention because of the versatility facing new shaping routes for manufacturing bulk pieces and, in particular, films and coatings. This work reviews the near-net shaping of ceramics through chemical gelation, among which two groups of techniques can be distinguished: those using monomers that polymerize by means of initiators/catalysts, and those using high molecular weight polysaccharides that develop a network structure by means of cations present in the medium. The last case is reviewed in this work, which presents the basis of the chemistry of alginates, focusing their structure and the gelation mechanism, and explores the viability of alginate gelation in the manufacture of thick films by tape casting on the basis of the processing parameters. Key words: Processing, Shaping, Suspensions, Processing additives, Chemical gelation, Alginates INTRODUCCIÓNLos costes totales de producción y el impacto medioambiental son aspectos determinantes para la implantación de un proceso de conformado. El procesamiento coloidal permite obtener piezas de forma compleja con un elevado control del número y tamaño de defectos, así como una alta reproducibilidad y fiabilidad (1,2,3). Por estas razones, se está realizando un gran esfuerzo en el desarrollo de nuevos métodos de conformado coloidal más versátiles y rentables (2,3). Una vía importante en este aspecto, es la fabri...

show abstract

Coagulation Kinetics and Mechanical Behavior of Wet Alumina Green Bodies Produced via DCC

Cited by 84 publications

References 8 publications

Recent trends in shape forming from colloidal processing: A review

Recent trends in shape forming from colloidal processing: A review

Nanoparticle assisted coagulation of aqueous alumina suspensions

Nuevas aplicaciones de los alginatos en el conformado cerámico

Contact Info

Product

Resources

About