Rheology and packing characteristics of alumina extrusion using boehmite gel as a binder

Fabrication of porous alumina ceramics from powder mixtures with sol–gel derived nanometer alumina: Effect of mixing method

“…However, as the nanomaterial percentage continues increasing above the threshold value, which was measured at around 8 wt% in our case, the combination of faster sintering kinetics and of better packing of particles results in the gradual decrease of porosity in consistency with literature results. 3,4,6,7,16 The better packing in case of bimodal distributions has been long discussed and an optimum packing at a fine powder content at around 20-30 wt% is reported 3,[5][6][7]12,[16][17][18] attributed to the filling of voids among the coarse particles with the small ones. It becomes obvious that the homogeneity has to play an important role in this combined phenomenon of both porosity and strength increase, because as the nanoparticles form large agglomerates, these would concentrate on the voids of coarse particles (even for low nanomaterial addition) and the effect on porosity increase would be less pronounced from the beginning.…”

Wall coating optimization for microchannel reactors

“…This in turn provides a reasonable fluidity of suspensions, even at high solid loading, since the boehmite behaves as a plasticizer [31] as well; (ii) the amount of polyelectrolyte adsorbed is increased due to the larger density of positive surface charges facilitating the anchoring of more carboxylic groups.…”

Effects of Milling pH and Hydrothermal Treatment on Formation of Nanostructured Boehmite Binder for Alumina Extrusion

“…Organic binders are transient processing additives that decompose during the firing step, generating potentially harmful hydrocarbon gases (e.g., C 3 H 5 , C 4 H 5 O, and C 5 H 8 O 2 ) and CO 2 which, once released to the atmosphere, contribute to the greenhouse effect [5]. Such environmental impact can be reduced by replacing the organics by inorganic binders, such as boehmite (aluminum oxyhydroxide, -AlOOH), which generates only water as gaseous byproduct [6,7]. The addition of boehmite 2 Journal of Nanomaterials nanoparticles to ceramic powders can produce pastes with adequate extrusion behaviors (plasticity and liquid retention capacity) resulting in formed bodies with characteristics (green density and strength) similar to those obtained for pastes containing plastic clays [7,8].…”

“…Such environmental impact can be reduced by replacing the organics by inorganic binders, such as boehmite (aluminum oxyhydroxide, -AlOOH), which generates only water as gaseous byproduct [6,7]. The addition of boehmite 2 Journal of Nanomaterials nanoparticles to ceramic powders can produce pastes with adequate extrusion behaviors (plasticity and liquid retention capacity) resulting in formed bodies with characteristics (green density and strength) similar to those obtained for pastes containing plastic clays [7,8]. Boehmite has also been used as a processing additive in other forming methods, such as sol-gel, cold isostatic pressing, and slurry compaction [9][10][11].…”