Rheological Studies on Aqueous Alumina Extrusion Mixes

Swathi, M.; Papitha, Ramanathan; Hareesh, U. S.; Saha, Bhaskar; Johnson, Roy; Vijayakumar, M.

doi:10.1007/s12666-011-0096-3

Cited by 6 publications

(5 citation statements)

References 8 publications

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“…The mixture is kneaded into extrudable dough using poly-ethylene glycol as plasticizer in a high shear vacuum sigma kneader to ensure the distribution of binder and hence high homogeneity of the dough. The dough which exhibits a shear thinning rheology and confirms the extrudablity is further extrusion shaped into components with dies of required geometry employing either a ram type or screw type extruder [14,15].…”

Section: Introductionmentioning

confidence: 69%

“…While kneading polyethylene glycol (1 wt.%) was added as a plasticizer together with water (30 wt.%). Both dough materials were characterized for their rheological properties using an indigenously designed and fabricated capillary extrusion rheometer and the procedure followed is described elsewhere [15]. Extrusion pressure, P, required for maintaining a stable flow through the capillary die were calculated from the steady state load values corresponding to the plateau region of the load displacement curve, as load per unit cross sectional area of the barrel, (4F/π • D 2 ), where F is the load and D is the diameter of the barrel.…”

Section: Sample Preparationmentioning

confidence: 99%

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Synthesis, extrusion processing and ionic conductivity measurements of sodium β-alumina tubes

Avinash

Suresh

Khanra

et al. 2015

PAC

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Pure and Li-doped sodium ?-alumina (NaMg0.67Al10.33O17) ceramics were prepared from the stoichiometric mixture of raw powders. Pellets and tubes were formed from the precursor (NBA-1S) and preformed sodium ?-alumina powder through compaction and extrusion processing, respectively. The obtained specimens were finally sintered to dense ceramics. The ceramics were comparatively evaluated for their density, microstructure, phase formation and electrical properties. Both tubes and pellets processed with the preformed sodium ?-alumina powder (NBA-2S) showed enhanced densification along with relatively better phase purity and crystallinity. The ceramics prepared from the preformed powder exhibited higher density of 94-95% TD (theoretical densities) in comparison to the ceramics processed from the raw mixture (NBA-1S) with a density of 85-87%TD, which are complemented well through fractographs and microstructures. The ceramics processed using the preformed sodium ?-alumina (NBA-2S) also exhibited high room temperature AC conductivity of 1.77?10-4 S/cm (1MHz) with an increasing trend with temperature. The higher ionic conductivity at all temperatures in NBA-2S than in NBA-1S ceramics can be attributed to the relatively high phase purity, crystallinity and higher density values of NBA-2S ceramics.

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Section: Introductionmentioning

confidence: 69%

Section: Sample Preparationmentioning

confidence: 99%

Synthesis, extrusion processing and ionic conductivity measurements of sodium β-alumina tubes

Avinash

Suresh

Khanra

et al. 2015

PAC

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“…Stereolithography (SLA) [11][12][13], binder jetting [14][15][16][17] and extrusion of ceramic pastes [18][19][20] are the 3D printing processes presently explored for ceramic shaping. As the current study is based on extrusion of alumina paste similar to fused deposition modeling shear thinning or pseudo-plastic behavior of the paste through proper selection of binder and plasticizing agents is critical [21][22][23]. Further, nozzle dimensions, self-standing distance of the extrudate, printing speed and interaction of the surface with the extrudate are found to have an effect on the process or printed parts.…”

Section: Introductionmentioning

confidence: 99%

Effect of parameters on 3D printing of alumina ceramics and evaluation of properties of sintered parts

Mamatha

Biswas

Ramavath

et al. 2021

Journal of Asian Ceramic Societies

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Paste rheology and printing parameters contribute to a great extent to engineer the properties of ceramic parts produced through 3D printing process. Alumina paste, which showed shear thinning behavior, was prepared using optimum concentration of additives. Paste was 3D printed and effect of printing parameters such as printing speed, length to diameter (L/D) ratio of nozzle, self-standing distance of extrudate, filling pattern and filling angle have been studied. Additionally, effect of the substrate material on which the extrudate is printed was also elucidated. A printing speed of 5-6 mm/s, an L/D ratio of 25 mm and self-standing distance of 1.25 ± 0.25 mm are found to be optimum. Further, a filling pattern of rectilinear geometry along with filling angle of 90° is found to be desirable. Out of the substrates evaluated, polished metal surface is found to be relatively better to achieve close tolerances. The alumina samples printed under optimized conditions are found to possess integrity with respect to the structure and close to pre-designed dimensions. Sintered samples were found to be free of crack and exhibited a density of 3.88 g/cc (97.5% of theoretical density). Density and hardness (16.5 GPa) of printed part correlates well with the microstructure consisting of grains of average size of 9.68 μm.

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“…This article describes the processing of MgAl 2 O 4 spinel by recently developed thermally induced MC–based colloidal forming technique for the shaping of honeycombs followed by pressure‐less sintering (PLS) and final densification by hot isostatic pressing (HIP). Various important parameters such as powder characteristics, rheological properties, drying, and sintering steps are found to be very critical for the shaping of defect free and homogeneous honeycomb structures which are the essential prerequisites for transparency . Honeycomb samples are characterized for their sintered density, microstructure, and the cellular properties such as relative density and surface‐to‐volume ratio.…”

Section: Introductionmentioning

confidence: 99%

“…Various important parameters such as powder characteristics, rheological properties, drying, and sintering steps are found to be very critical for the shaping of defect free and homogeneous honeycomb structures which are the essential prerequisites for transparency. 12,13 Honeycomb samples are characterized for their sintered density, microstructure, and the cellular properties such as relative density and surface-to-volume ratio. The flat samples were also processed under identical conditions and were further subjected to optical measurement followed by evaluation of a few of the physicochemical and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Transparent Spinel Honeycomb Structures by Methyl Cellulose–Based Thermal Gelation Processing

et al. 2013

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Transparent MgAl 2 O 4 spinel of flat as well as honeycomb structure was fabricated by employing thermally induced gel casting of the slurry with 56 wt% solid loading containing 0.2 wt% of methylcellulose. The green specimens were pressureless sintered to 98%-99% of theoretical density with no open porosity at an optimum temperature of 1700°C. Final densification by hot isostatic pressing of both the specimens at the optimum temperature of 1800°C and 195 MPa pressure enabled further elimination of residual porosities and full densification resulting in theoretical density of 3.58 g/cc. The design of the honeycomb was such that it exhibited a surface area to volume ratio of 0.65 cm 2 /cm 3 and a relative density of 0.69. The hardness of the honeycomb specimens has been found to be 13 GPa, which is at par with the solid specimens processed under identical conditions. Solid specimens of around 4 mm thickness exhibited a transmission of >80% in the visible (0.4-0.8 lm) region. Specimens were also tested according to ASTM procedures and have shown a flexural strength (r f ) of 195 MPa and plane-strain fracture toughness (K Ic ) of 1.87 MPaÁm 1/2 as reported in this study.

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Rheological Studies on Aqueous Alumina Extrusion Mixes

Cited by 6 publications

References 8 publications

Synthesis, extrusion processing and ionic conductivity measurements of sodium β-alumina tubes

Synthesis, extrusion processing and ionic conductivity measurements of sodium β-alumina tubes

Effect of parameters on 3D printing of alumina ceramics and evaluation of properties of sintered parts

Fabrication of Transparent Spinel Honeycomb Structures by Methyl Cellulose–Based Thermal Gelation Processing

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