The influence of lignosulphonate on the properties of single and mixed Si3N4 and ZrO2 suspensions

Byman-Fagerholm, Hedvig; Mikkola, Pasi; Rosenholm, Jarl B.; Lidén, Eva; Carlsson, Roger

doi:10.1016/s0955-2219(98)00162-9

Cited by 20 publications

(7 citation statements)

References 13 publications

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“…There are relatively few positive sites available for adsorption. Nevertheless, the adsorption of poly(acrylic acid)s and the consequential increase of negative charges at the surface are well-established − and have also been reported for lignosulfonates. ,, We have shown in a previous work that the ζ-potential at pH 9 increases from almost zero for a bare alumina surface to approximately −40 and −30 mV through adsorption of the poly(acrylic acid) and the lignosulfonate, respectively, that are used as dispersants in the present work . These dispersants were consequently referred to as dispersants providing electrostatic stabilization.…”

Section: Resultssupporting

confidence: 54%

Dispersant Adsorption and Viscoelasticity of Alumina Suspensions Measured by Quartz Crystal Microbalance with Dissipation Monitoring and in Situ Dynamic Rheology

Palmqvist

Holmberg

2008

Langmuir

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Adsorption behavior and water content of adsorbed layers of four dispersants for aqueous ceramic processing were studied by quartz crystal microbalance with dissipation monitoring (QCM-D) on alumina surfaces. The dispersants were a poly(acrylic acid), a lignosulfonate, and two hydrophilic comb copolymers with nonionic polyoxyethylene chains of different molecular weights. A Voigt model was applied to analyze the viscoelastic behavior of the adsorbed dispersant layers. The results from QCM-D were compared with viscoelastic properties determined by in situ dynamic rheology measurements of highly concentrated alumina suspensions during slip casting. The QCM-D results showed that both the poly(acrylic acid) and the lignosulfonate adsorbed in low amounts and in a flat conformation, which generated thin, highly rigid layers less than 1 nm thick. The water content of these layers was found to be around 30% for the lignosulfonate and 35% for the poly(acrylic acid). High casting rate and strength in terms of storage modulus were observed in the final consolidate of the suspensions with the two polyelectrolytes. In contrast, the high molecular weight comb copolymer adsorbed in a less elastic layer with a thickness of about 6 nm, which is enough to provide steric stabilization. The viscous behavior of this layer was attributed to high water content, which was calculated to be around 90%. Such a water-rich layer gives a lubrication effect, which allows for reorientation of particles during the consolidation process, resulting in a high final strength of the ceramic material. During consolidation, the suspension showed a slow casting rate, most likely due to rearrangement facilitated by the lubricating layer. The short-chain comb copolymer adsorbed in a 1.5 nm thick, rigid layer and gave low final strength to the consolidated suspension. It is likely that the poor consolidation behavior is caused by flocculation due to insufficient stabilization of the dispersion.

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Section: Resultssupporting

confidence: 54%

Dispersant Adsorption and Viscoelasticity of Alumina Suspensions Measured by Quartz Crystal Microbalance with Dissipation Monitoring and in Situ Dynamic Rheology

Palmqvist

Holmberg

2008

Langmuir

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“…[1][2][3][4][5] In aqueous systems, charged polyelectrolytes are commonly used as dispersants to enhance suspension stability and to impede particle flocculation, thus leading to both high solid loadings and low viscosities. [6][7][8][9][10] The adsorption of polyelectrolyte molecules onto the surface of the powder results in the formation of a double electrostatic layer that surrounds each particle and leads to electrostatic repulsive generally considered as weak in comparison to that of the dispersant. This generates an heterogeneous distribution of the organic phase in the ceramic green part.…”

Section: Introductionmentioning

confidence: 99%

A new processing aid for dry-pressing: A copolymer acting as dispersant and binder

Romdhane

Chartier

Baklouti

et al. 2007

Journal of the European Ceramic Society

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“…The detrimental effect of unadsorbed dispersant on the stabilization of suspensions also has been reported by others. 26 According to Fagerholm et al, 28 the optimum dispersant amount is independent on the solids loading. However, in the present study, the optimum dispersant amount increases with solids loading.…”

Section: July 2003mentioning

confidence: 99%

Effect of 2‐Phosphonobutane‐1,2,4‐tricarboxylic Acid Adsorption on the Stability and Rheological Properties of Aqueous Nanosized 3‐mol%‐Yttria‐Stabilized Tetragonal‐Zirconia Polycrystal Suspensions

Liu

Gao

2003

Journal of the American Ceramic Society

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2‐phosphonobutane‐1,2,4‐tricarboxylic acid (PBTCA) was evaluated as a dispersant for nanosized 3‐mol%‐Y2O3‐stabilized tetragonal‐ZrO2 polycrystal (3Y‐TZP) suspensions. The adsorption of PBTCA was characterized using the decolorization method of ferric 5‐nitrosalicylate complexes. Maximum adsorption of the dispersant on the 3Y‐TZP powder was found to occur at pH 3.0. At pH >3.0, the adsorbed amount decreased with increased pH. Semiquantitative analysis using auger electron spectroscopy showed that PBTCA adsorbed irreversibly on the powder. The surface charge of the powder was evaluated by measuring the zeta‐potential in dilute powder suspensions. The suspension was most effectively stabilized at high pH by the high charge induced by the adsorption of PBTCA. Rheological properties of the suspension were evaluated as a function of dispersant amount and solids loading. The optimum amount of dispersant increased with increased solids loading for solids loading >20 vol%. A stable suspension of 35 nm 3Y‐TZP particles with a solids loading as high as 32 vol% was obtained using PBTCA as dispersant, in contrast to 28 vol% when using ammonium polyacrylate (NH4PAA). Theoretical calculations of the interaction between 3Y‐TZP particles showed that the stabilization of the suspensions was attributed to a combination of the electrostatic repulsion and a steric barrier caused by the adsorbed PBTCA. Induced coupling plasma analysis showed that PBTCA could be completely burned out during sintering, which confirmed its suitability as a dispersant for 3Y‐TZP.

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The influence of lignosulphonate on the properties of single and mixed Si3N4 and ZrO2 suspensions

Cited by 20 publications

References 13 publications

Dispersant Adsorption and Viscoelasticity of Alumina Suspensions Measured by Quartz Crystal Microbalance with Dissipation Monitoring and in Situ Dynamic Rheology

Dispersant Adsorption and Viscoelasticity of Alumina Suspensions Measured by Quartz Crystal Microbalance with Dissipation Monitoring and in Situ Dynamic Rheology

A new processing aid for dry-pressing: A copolymer acting as dispersant and binder

Effect of 2‐Phosphonobutane‐1,2,4‐tricarboxylic Acid Adsorption on the Stability and Rheological Properties of Aqueous Nanosized 3‐mol%‐Yttria‐Stabilized Tetragonal‐Zirconia Polycrystal Suspensions

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