alumina gels
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2017 ◽  
Vol 89 (7) ◽  
pp. 935-943 ◽  
Author(s):  
Frederik Berg ◽  
Christoph Pasel ◽  
Michael Luckas ◽  
Tobias Eckardt ◽  
Dieter Bathen


2017 ◽  
Vol 23 (2) ◽  
pp. 423-433 ◽  
Author(s):  
Zongwen Fu ◽  
Matthias Freihart ◽  
Tobias Schlordt ◽  
Tobias Fey ◽  
Torsten Kraft ◽  
...  

Purpose This study aims to achieve the fabrication of three-dimensional core-shell filament-based lattice structures by means of robocasting combined with co-extrusion. For core and shell materials, colloidal gels composed of submicron carbon and alumina powders were developed, respectively. Simultaneously, the co-extrusion process was also studied by numerical simulation to investigate the feed pressure-dependent wall thickness. Design/methodology/approach Significant differences in the rheological behavior of the carbon and alumina gels were observed because of differences of the particle morphology and surface chemistry of the carbon and alumina powders. Precise control over the cross-sectional diameter of the core and shell green state elements was achieved by alteration of the feed pressures used during co-extrusion. Findings After subsequent thermal treatment in an oxidizing atmosphere (e.g. air), in which the carbon core was oxidized and burned out, lattice structures formed of hollow filaments of predetermined wall thickness were manufactured; additionally, C-Al2O3 core-shell filament lattice structures could be derived after firing in an argon atmosphere. Originality/value Green lattice truss structures with carbon core and alumina shell filaments were successfully manufactured by robotically controlled co-extrusion. As feedstocks carbon and alumina gels with significantly different rheological properties were prepared. During co-extrusion, the core paste exhibited a much higher viscosity than the shell paste, which benefited the co-extrusion process. Simultaneously, the core and shell diameters were exactly controlled by core and shell feed pressures and studied by numerical simulation. The experimentally and numerically derived filament wall thickness showed qualitative agreement with each other; with decreasing core pressure during co-extrusion, the wall thickness increased.



2016 ◽  
Vol 34 (12) ◽  
pp. 1501-1509 ◽  
Author(s):  
F. Achchaq ◽  
A. Godin ◽  
M. Duquesne ◽  
K. Djellab ◽  
J. R. Puiggali ◽  
...  


2014 ◽  
Vol 97 (12) ◽  
pp. 4031-4036 ◽  
Author(s):  
Kiran Yadav ◽  
Manjeet Jassal ◽  
Ashwini K. Agrawal
Keyword(s):  




2007 ◽  
Vol 30 (1) ◽  
pp. 367-373 ◽  
Author(s):  
Brian Cormack ◽  
John J. Freeman ◽  
Kenneth S. W. Sing


Langmuir ◽  
2007 ◽  
Vol 23 (8) ◽  
pp. 4532-4540 ◽  
Author(s):  
Joseph M. Fedeyko ◽  
Heather Egolf-Fox ◽  
Dustin W. Fickel ◽  
Dionisios G. Vlachos ◽  
Raul F. Lobo


2002 ◽  
Vol 110 (1287) ◽  
pp. 1025-1028 ◽  
Author(s):  
Yukari TAKEDA ◽  
Tadanori HASHIMOTO ◽  
Hiroyuki NASU ◽  
Kanichi KAMIYA


2001 ◽  
Vol 16 (5) ◽  
pp. 1413-1419 ◽  
Author(s):  
G. S. Grader ◽  
S. A. Melchior ◽  
Y. De-Hazan ◽  
S. Melamed ◽  
G. E. Shter

This work describes the entrapment of tetrakis(trimethylsilyl)silane (TK) and tetrakis(chlorodimethylsilyl)silane (TKCl) in nonhydrolytic alumina gels, and the materials' thermal behavior. During gelation and drying TK and TKCl are physically entrapped in the gel up to a limit of Si/Al = 0.33. Above this limit, sublimation and decomposition of TK and TKCl occur during heating. A larger fraction of TKCl decomposition products is retained due to their higher reactivity. Below and above Si/Al = 0.33, the gel converts to mullite + α−Al2O3or mullite + amorphous silica, respectively. Conversion to hexagonal mullite indicates atomic scale homogeneity of Si and Al during firing.



2000 ◽  
Vol 362 (1-2) ◽  
pp. 37-48 ◽  
Author(s):  
J.L Szetu ◽  
R.L Frost ◽  
J.T Kloprogge ◽  
S.C Russell ◽  
W Martens


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