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Robocasting of Alumina Lattice Truss Structures
T. Schlordt, F. Keppner, N. Travitzky, P. Greil
Department of Materials Science, Glass and Ceramics, Friedrich-Alexander-University Erlangen-Nuernberg, Martensstr. 5, 91058 Erlangen, Germany
received January 20, 2012, received in revised form February 8, 2012, accepted February 25, 2012
Vol. 3, No. 2, Pages 81-88 DOI: 10.4416/JCST2012-00003
Abstract
Robocasting of aqueous colloidal α-Al2O3 gels for manufacturing cellular ceramics with periodical lattice truss structures was investigated. Coagulation of gels loaded with 48 vol% α-Al2O3 was induced by adding CH3COONH4. The gels exhibit shear-thinning behavior, shear elastic moduli ranging from 6.7 to 390 kPa and yield-stresses from 25 to 570 Pa. Continuous filaments with a diameter of 0.5 mm were extruded with a deposition speed of up to 35 mm/s on a high-precision six-axis robotic system equipped with a single-screw micro-extruder. The lattice structures consist of alternating layers formed by a linear array of circular rods aligned parallel with a distance of 1 mm and an angle of 90° between alternating layers. After being dried for 12 h, the robocast grids were sintered in air at 1650 °C for 2 h resulting in a fractional strut density > 0.95, a mean filament diameter of 400 μm, a volume filling fraction of 0.49 (sealed walls) and 0.35 (meshed walls), and macro-cells in the deposition plane of quadratic shape with a mean area of 0.136 mm2 ± 0.017 mm2 Based on gravitation-driven viscous flow, model conditions for attaining free spanning ligaments were discussed.
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Keywords
Robocasting, alumina gel, lattice truss structures
References
1 Lewis, J.A., Smay, J.E., Stuecker, J., Cesarano III, J.: Direct ink writing of three-dimensional ceramic structures (feature), J. Am. Ceram. Soc., 89, 3599 – 609, (2006).
2 Cesarano III, J., Segalman, R., Calvert, P.: Robocasting provides moldless fabrication from slurry deposition, Ceram. Ind., 148, 94 – 102, (1998).
3 Lewis, J.A.: Direct ink writing of 3D functional materials, Adv. Funct. Mater., 16, 2193 – 204, (2006).
4 Smay, J.E., Cesarano III, J., Lewis, J.A.: Colloidal inks for directed assembly of 3-D periodic structures, Langmuir, 18, 5429 – 37, (2002).
5 Morissette, S.L., Lewis, J.A., Cesarano III, J., Dimos, D.B., Baer, T.: Solid freeform fabrication of aqueous alumina-poly(vinyl alcohol) gelcasting suspensions, J. Am. Ceram. Soc., 83, 2409 – 16, (2000).
6 San Marchi, C., Kouzeli, M., Rao, R., Lewis, J.A., Dunand, D.C.: Alumina-aluminum interpenetrating phase composites with three-dimensional periodic structure, Scr. Mater., 49, 861 – 6, (2003).
7 Mason, M.S., Huang, T., Landers, R.G., Leu, M.C., Hilmas, G.E.: Aqueous-based extrusion of high-solids loading ceramic pastes: process modeling and control, J. Mater. Proc. Tech., 209, 2946 – 57, (2009).
8 Stuecker, J.N., Cesarano III, J., Hirschfeld, D.A.: Control of the viscous behavior of highly concentrated mullite suspensions for robocasting, J. Mater.Proc. Tech., 142, 318 – 25, (2003).
9 Smay, J. E., Cesarano III, J., Tuttle, B.A., Lewis, J.A.: Directed colloidal assembly of linear and annular lead zirconate titanate arrays, J. Am. Ceram. Soc., 87, 293 – 5, (2004).
10 Miranda, P., Saiz, E., Gryn, K., Tomsia, A.P.: Sintering and robocasting of β-tricalcium phosphate scaffolds for orthopaedic applications, Acta Biomater., 2, 457 – 66, (2006).
11 Saiz, E., Gremillard, L., Menedez, G., Miranda, P., Gryn, K., Tomsia, A. P.: Preparation of porous hydroxyapatite scaffolds, Mater. Sci. Eng., 27, 546 – 50, (2007).
12 Şakar-Deliormanli, A., Ãelik, E., Polat, M.: Rheological behavior of PMN gels for solid freeform fabrication, Colloids Surf. A, 324, 159 – 66, (2008).
13 Wang, J., Shaw, L.L.: Rheological and extrusion behavior of dental porcelain slurries for rapid prototyping applications, Mater. Sci. Eng. A, 397, 3314 – 21, (2005).
14 Nadkarni, S.S., Smay, J.E.: Concentrated barium titanate colloidal gels prepared by bridging flocculation for use in solid freeform fabrication, J. Am. Ceram. Soc., 89, 96 – 103, (2006).
15 Kiratzis, N., Faers, M., Luckham, P.F.: Depletion flocculation of particulate systems induced by hydroxyethylcellulose, Colloids Surf. A, 151, 461 – 71, (1999).
16 Nickerson, C.S., Kornfield, J.A.: A "cleat" geometry for suppressing wall slip, J. Rheol., 49, 865 – 74, (2005).
17 Roberts, M.T., Mohraz, A., Christensen, K.T., Lewis, J.A.: Direct flow visualization of colloidal gels in microfluidic channels, Langmuir, 23, 8726 – 31, (2007).
18 Krieger, I. M.: Rheology of monodisperse lattices, Adv. Colloid. Interf. Sci., 3: 111 – 36, (1972).
19 Choi, G.N., Krieger, I.M.: Rheological studies on sterically stabilized model dispersions of uniform colloidal spheres: II. steady-shear viscosity, Adv. Colloid. Interf. Sci., 113, 101 – 13, (1986).
20 Lewis, J. A.: Colloidal processing of ceramics, J. Am. Ceram. Soc., 83, 2341 – 59, (2000).
21 Greener, J., Evans, J.R.G.: Uniaxial elongational flow of particle-filled polymer melts, J. Rheol., 42, 697 – 710, (1998).
22 Buscall, R., McGowan, J.I., Morton-Jones, A.J.: The rheology of concentrated dispersions of weakly attracting colloidal particles with and without wall slip, J. Rheol., 37, 621 – 41, (1993).
23 Herschel, W.H., Bulkley, R.: Consistency measurements of rubber-benzene solutions (in german), Kolloid Z., 39, 291 – 300, (1926).
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