Design of ceramic paste formulations for co-extrusion

Powell, J. G. F.; Assabumrungrat, Suttichai; Blackburn, S.

doi:10.1016/j.powtec.2013.04.017

Cited by 33 publications

(19 citation statements)

References 21 publications

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“…Since the die of the extruder used here is a frustum of a cone rather than a cylinder, instead of directly calculating the extrusion pressures P 1 and P 2 , the corresponding forces are used. The total force was plotted as a function of L d / D d ratios for different velocities (similar to a Bagley plot) . Extrapolating the linear relationship between L d / D d and the extrusion force for different velocities back to the Y ‐axis gives the force at L d / D d = 0, which corresponds to the force required to converge the paste into the die entry ( F 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…For the superplasticized mixtures, τ W is always lower than those for the non‐superplasticized mixtures. In essence, slip in paste extrusion flow results from the depletion of solid particles from the wall, that results in the formation of a lubrication layer, where the liquid itself has a die wall velocity of zero . It has been reported that for hard‐sphere suspensions, slip flow is more significant, within limits, for pastes with higher solid loadings (for eg, superplasticized mixtures, in this case), because the particles crowd and lock in place, reducing Brownian motions that disturb the slip layer .…”

Section: Resultsmentioning

confidence: 99%

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Linking fresh paste microstructure, rheology and extrusion characteristics of cementitious binders for 3D printing

et al. 2019

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Cementitious binders amenable to extrusion-based 3D printing are formulated by tailoring the fresh microstructure through the use of fine limestone powder or a combination of limestone powder and microsilica or metakaolin. Mixtures are proportioned with and without a superplasticizer to enable different particle packings at similar printability levels. A simple microstructural parameter, which implicitly accounts for the solid volume and inverse square dependence of particle size on yield stress can be used to select preliminary material combinations for printable binders. The influence of composition/microstructure on the response of pastes to extension or squeezing are also brought out. Extrusion rheology is used in conjunction with a phenomenological model to better understand the properties of significance in extrusion-based printing of cementitious materials. The extrusion yield stress and die wall slip shear stress extracted from the model enables an understanding of their relationships with the fresh paste microstructure, which are crucial in selecting binders, extrusion geometry, and processing parameters for 3D printing. K E Y W O R D S3D printing, extrusion, microstructure, rheology, wall shear stress, yield stress

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Linking fresh paste microstructure, rheology and extrusion characteristics of cementitious binders for 3D printing

et al. 2019

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“…The extrudates were collected prior to the rapid increase in pressure to minimize the influence of other high shear based factors on the microstructure. As suggested in this paper [33] the extrusion pressure was calculated as the average value from the data that were collected at a given velocity over a piston displacement of at least 5.0 mm.…”

Section: Extrusion Conditions and Paste Flowmentioning

confidence: 99%

Visualizing the Effect of Extrusion Velocity on the Spatial Variation of Porosity in a Titanium Dioxide/Binder System

Alazzawi¹,

Murali²,

Haber³

2017

MSA

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Extrusion is a common process technique used to fabricate porous materials such as catalysts and membranes. The performance and efficiency of such materials are governed by porosity and pore distribution. The spatial variation of porosity within the catalyst structure can be linked to process variables in the extrusion processes such as extrusion velocity. A change in extrusion velocity can lead to a change in extrusion pressure. The extrusion pressure effect is a combination of die entry deformation and frictional die land shear. In this work, the effect of extrusion velocity on the spatial variation of porosity in a titania-binder extrudate has been studied. Capillary rheometer analysis was done to investigate the effect of extrusion velocity. A segmentation approach was developed to study the spatial variation of porosity at the die wall (sheared region) compared to the unsheared (center) region of the extrudate. The results show that the extrusion pressure effect increases as the velocity increases. The extrusion conditions affect the spatial variation of porosity.

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“…In the Benbow–Bridgwater extrusion model, the pressure is the sum of the pressure required by the billet and the container. The required pressure depends on the exit diameter, exit die length, and the ratio between them, as well as the billet material properties . In recent years, most studies of this subject have explored the rheological behavior in single‐layer or multilayer extrusion …”

Section: Introductionmentioning

confidence: 99%

“…The required pressure depends on the exit diameter, exit die length, and the ratio between them, as well as the billet material properties. [6][7][8][9] In recent years, most studies of this subject have explored the rheological behavior in single-layer or multilayer extrusion. [8][9][10][11] In the WC-Co phase diagram, a WC solid phase and a Co-rich liquid phase are formed when WC-Co is sintered at 1400°C.…”

Section: Introductionmentioning

confidence: 99%

cBN–TiC and WC–Co Composites: Optimization of Co‐Extruding Conditions

Zheneng¹,

Wang

et al. 2015

Int J Applied Ceramic Tech

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In this study, double-layer tubes with inner-layer cubic boron nitride-titanium carbide (cBN-TiC) and outer-layer tungsten carbide-cobalt (WC-Co) were fabricated by co-extrusion. The Taguchi method was used to determine the optimal parameters, including extrusion ratio, half-die angle, extrusion speed, and binder amount. The double-layer tube made using these optimal parameters had an inner-layer hardness of 3825 Hv and an outer-layer hardness of 1849 Hv. The porosity of the double-layer tube was 10.4%. Furthermore, the crystalline structures obtained from the inner and outer layers were cBN, TiC, TiB 2 , and BNi and WC and Co 2 C phases.

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Design of ceramic paste formulations for co-extrusion

Cited by 33 publications

References 21 publications

Linking fresh paste microstructure, rheology and extrusion characteristics of cementitious binders for 3D printing

Linking fresh paste microstructure, rheology and extrusion characteristics of cementitious binders for 3D printing

Visualizing the Effect of Extrusion Velocity on the Spatial Variation of Porosity in a Titanium Dioxide/Binder System

cBN–TiC and WC–Co Composites: Optimization of Co‐Extruding Conditions

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