Abstract:In the present investigation aqueous suspensions of nano-and colloidal range particles are stabilised by changing the ambient pH. Rheology is used to establish the stability of the suspensions and it is found that the rheology of the suspensions is strongly dependent on the pH values. The viscosity is highest close to the iso-electric point of the powders. At the iso-electric point the net surface charge on the powder particles is zero and is the cause of the high viscosity. Away from the iso-electric point, t… Show more
“…Alumina, 1-8 zirconia, [9][10][11][12][13][14][15][16] yttrium stabilized zirconia (YSZ), [17][18][19] and titania [20][21][22] are some of the most widely studied ceramic nanopowder systems. An understanding of the surface properties and the rheological behavior of oxide nanopowder suspensions is essential for many applications, including nanofluids, [23][24][25][26][27] advanced ceramics, 10,28,29 nanocomposites, 25,30 and others.…”
Section: Introductionmentioning
confidence: 99%
“…An understanding of the surface properties and the rheological behavior of oxide nanopowder suspensions is essential for many applications, including nanofluids, [23][24][25][26][27] advanced ceramics, 10,28,29 nanocomposites, 25,30 and others. Lower suspension viscosities facilitate improved end-product quality as they indicate better dispersed systems, and lower production costs.…”
“…Alumina, 1-8 zirconia, [9][10][11][12][13][14][15][16] yttrium stabilized zirconia (YSZ), [17][18][19] and titania [20][21][22] are some of the most widely studied ceramic nanopowder systems. An understanding of the surface properties and the rheological behavior of oxide nanopowder suspensions is essential for many applications, including nanofluids, [23][24][25][26][27] advanced ceramics, 10,28,29 nanocomposites, 25,30 and others.…”
Section: Introductionmentioning
confidence: 99%
“…An understanding of the surface properties and the rheological behavior of oxide nanopowder suspensions is essential for many applications, including nanofluids, [23][24][25][26][27] advanced ceramics, 10,28,29 nanocomposites, 25,30 and others. Lower suspension viscosities facilitate improved end-product quality as they indicate better dispersed systems, and lower production costs.…”
“…The casting from aqueous slips is widely used for manufacturing thin-walled hollow and solid green bodies from either construction or technical ceramics [124][125][126][127][128][129][130][131]. For making solid green bodies, Processes 2020, 8, 1004 20 of 37 additional doses of the slip are added to the mold several times.…”
Ceramic matrix composites reinforced with carbon nanotubes are becoming increasingly popular in industry due to their astonishing mechanical properties and taking into account the fact that advanced production technologies make carbon nanotubes increasingly affordable. In the present paper, the most convenient contemporary methods used for the compaction of molding masses composed of either technical ceramics or ceramic matrix composites reinforced with carbon nanotubes are surveyed. This stage that precedes debinding and sintering plays the key role in getting pore-free equal-density ceramics at the scale of mass production. The methods include: compaction in sealed and collector molds, cold isostatic and quasi-isostatic compaction; dynamic compaction methods, such as magnetic pulse, vibration, and ultrasonic compaction; extrusion, stamping, and injection; casting from aqueous and non-aqueous slips; tape and gel casting. Capabilities of mold-free approaches to produce precisely shaped ceramic bodies are also critically analyzed, including green ceramic machining and additive manufacturing technologies.
“…This interaction can be controlled with chemical additives in three different ways: electrostatic, steric and electrosteric stabilization [8][9][10]. The selection of dispersant is a critical step in slurry preparation because it might be difficult to find a dispersant that is optimal for all suspension components and for establishing control over the suspension stability and its rheological properties [11,12]. To select the optimal suspension dispersant, it is recommended to conduct preliminary viscosity measurements and sedimentation tests with the variation of type and content of dispersants and binders.…”
In this work, alumina (Al2O3) ceramics were prepared using an environmentally friendly slip casting method. To this end, highly concentrated (70 wt.%) aqueous suspensions of alumina (Al2O3) were prepared with different amounts of the ammonium salt of a polycarboxylic acid, Dolapix CE 64, as an electrosteric dispersant. The stability of highly concentrated Al2O3 aqueous suspensions was monitored by viscosity measurements. Green bodies (ceramics before sintering) were obtained by pouring the stable Al2O3 aqueous suspensions into dry porous plaster molds. The obtained Al2O3 ceramic green bodies were sintered in the electric furnace. Analysis of the effect of three sintering parameters (sintering temperature, heating rate and holding time) on the density of alumina ceramics was performed using the response surface methodology (RSM), based on experimental data obtained according to Box–Behnken experimental design, using the software Design-Expert. From the statistical analysis, linear and nonlinear models with added first-order interaction were developed for prediction and optimization of density-dependent variables: sintering temperature, heating rate and holding time.
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