Aqueous injection moulding of porcelains

Santacruz, Isabel; Nieto, Ma I.; Moreno, Rodrigo; Ferrandino, P.; Salomoni, A.; Stamenkovic, I.

doi:10.1016/s0955-2219(03)00018-9

Cited by 20 publications

(23 citation statements)

References 2 publications

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“…Solutions of agar were prepared at concentrations of 6 wt% by heating in a pressure vessel [14,15] in order to achieve the 110ºC required for its full dissolution without the water boiling.…”

Section: Methodsmentioning

confidence: 99%

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Gel casting of aqueous suspensions of BaTiO3 nanopowders

Santacruz¹,

Nieto²,

Binner³

et al. 2009

Ceramics International

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Commercial nano BaTiO 3 powders have been formed into green bodies using colloidal forming routes. A study of the rheological behaviour of the suspensions as a function of dispersant concentration and homogenisation time was made in order to prepare stable concentrated suspensions of the nanopowders. Bulk components were then manufactured using aqueous slip and gel casting involving polysaccharides that gel on cooling, i.e. agar. The performance of theses consolidation techniques for obtaining dense green bodies from the BaTiO 3 nanopowders was studied. It was possible to prepare relatively big gel cast samples with a similar density and microstructure and in a shorter time compared to those obtained by slip casting. Another difficulty found in nanoceramics manufacturing is the shaping of homogeneous green bodies. In general, colloidal processing allows the production of complex-shaped parts with a decreased number and size of pores and hence higher reliability 6 . In colloidal systems the interfaces play a key role in the surface properties, such as adsorption, surface charge, electric double layer, etc [6,7]. In the case of 3 nanosized particles, their massive surface areas and hence substantial interaction forces between the particles make it more difficult to prepare stable nano-particle suspensions and study their colloidal properties.Over the last few years, significant effort has been devoted to developing new forming methods for manufacturing complex-shaped ceramic products with minimal number of detrimental defects [8][9][10] This work aims to study the preparation and rheological characterisation of concentrated aqueous suspensions of commercial nanosized powders of barium titanate (nanoBT) for shape forming by slip and gel casting, the latter using thermogelling polysaccharides. The performance of these consolidation techniques for obtaining dense green bodies from the BT nanopowder is discussed. ExperimentalThe starting material was a commercial nanoBT powder (HPB-1000, TPL Inc., was added as a deflocculant to the solution [20,27] prior to the addition of sufficient of the nanoBT powder to generate suspensions with solids loadings of 70, 75 and 80 wt% (28, 33 and 40 vol%, respectively). The suspensions were mixed using by mechanical agitation with helices and further homogenised using ultrasound (a 400 W sonication probe, UP400S, Hielscher Ultrasonics GmbH, Stuttgart, Germany) for up to 10 min.Suspensions were cooled in an ice-water bath during ultrasonication in order to avoid heating.A commercially available agar (Grand Agar, Hispanagar S.A., Burgos, Spain) was used as the gelling agent. Solutions of agar were prepared at concentrations of 6 wt% by heating in a pressure vessel [14,15] in order to achieve the 110ºC required for its full dissolution without the water boiling.The rheological behaviour of the suspensions was studied using a rheometer (Haake RS50, Karlsruhe, Germany) with a double-cone and plate measuring system, provided with a solvent trap to reduce evaporation. Flow curves...

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Section: Methodsmentioning

confidence: 99%

“…~40 o C for the 6 wt% solution [14,15]. The agar solution was then added to the nanosuspension at a concentration of 0.5 wt% with respect to the dry solids content whilst maintaining a temperature of >50ºC.…”

Section: Methodsmentioning

confidence: 99%

Gel casting of aqueous suspensions of BaTiO3 nanopowders

Santacruz¹,

Nieto²,

Binner³

et al. 2009

Ceramics International

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show abstract

“…Solutions of agar were prepared to concentrations of 6 wt% by heating in a pressure vessel in order to achieve the high temperatures, 110ºC, required for its full dissolution 2 . The rheological behavior of the suspensions was studied through control rate measurements using a rheometer (Haake RS50, Germany) with a double-cone and plate system.…”

Section: Suspensions Preparationmentioning

confidence: 99%

Wet forming of concentrated nano-BaTiO3 suspensions

Santacruz

Nieto

Binner

et al. 2009

Journal of the European Ceramic Society

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“…9 In the last few years, significant effort has been devoted toward developing near-net-shaping methods for manufacturing complex-shaped ceramic products with a minimum number of defects. [10][11][12][13][14][15] Among them, slip casting is the most common technique for consolidating ceramic suspensions into complex shapes, 16 although long forming times are often needed, especially when nanosuspensions are being used.…”

Section: Introductionmentioning

confidence: 99%

Dispersion and Rheology of Aqueous Suspensions of Nanosized BaTiO₃

Santacruz

Binner

Nieto

et al. 2010

Int J Applied Ceramic Tech

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The zeta potential and the rheological behavior of aqueous suspensions of a commercial nanosized BaTiO 3 powder were studied. The influence of the volume fraction of solids, the kind and concentration of dispersant, the homogenization technique, and times were investigated. Because the as-received powder contained B5 wt% organics, the powder was calcined to 3501C/0.5 h. After calcination, a good dispersion was achieved for suspensions with up to 80 wt% solids using a polyacrylicbased dispersant combined with tetramethylammonium hydroxide and 10 min of ultrasound. Green bodies obtained by slip casting had relatively low densities (2.6 g/cm 3 , 43% TD), but homogeneous, agglomerate-free microstructures.

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Aqueous injection moulding of porcelains

Cited by 20 publications

References 2 publications

Gel casting of aqueous suspensions of BaTiO3 nanopowders

Gel casting of aqueous suspensions of BaTiO3 nanopowders

Wet forming of concentrated nano-BaTiO3 suspensions

Dispersion and Rheology of Aqueous Suspensions of Nanosized BaTiO₃

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Aqueous injection moulding of porcelains

Cited by 20 publications

References 2 publications

Gel casting of aqueous suspensions of BaTiO3 nanopowders

Gel casting of aqueous suspensions of BaTiO3 nanopowders

Wet forming of concentrated nano-BaTiO3 suspensions

Dispersion and Rheology of Aqueous Suspensions of Nanosized BaTiO3

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Dispersion and Rheology of Aqueous Suspensions of Nanosized BaTiO₃