L Zhang et al. Joumal of the European Ceramic Society 30(2010)1195-1202 clectrode Fig. 2. EPD cell with horizontally positioned deposition electrode counter deposition electrode electrode magnetic stirrer bar To estimate the influence of the electric field force, gravity and hydrodynamic force on the alignment of the platelets, two different set-ups were used, i.e., with a vertical and horizontal EPD cell. Three configurations were studied in a slightly mod- .V Spot Magn Det WD Exp ified horizontal cell as summarised in Table 1. The standard horizontal EPD cell is schematically presented in Fig. 2. In case of an applied suspension flow(configuration 2 in Table 1),a Fig. 1. SEM image of (a) as received alumina grade SM8 and(b) platelets suspension was flown through the deposition cell by means of a suspension circulation system driven by a peristaltic pump Tosoh grade TZ-3Y) with a diameter of 5 mm were added to The distance between the flat disc shaped electrodes was 3. 5 cm the polyethylene container to facilitate breaking the agglomer- and the electrodes had a diameter of 3. 7 cm. The suspension ates. Afterwards, platelets (5 wt% relative to the total amount in the reservoir was stirred to avoid sedimentation. In addition of powder) were added to the ball-milled suspension, whilst the flow-through system also decreases the sedimentation of the n-butylamine (99.5% Acros Belgium, 3. 4 vol% relative to the suspension in the cell with the fluid flow. Homogeneous deposits suspension volume)was added to negatively charge the particles were made by pumping 200 ml suspension at 1 ml/s through the and Dolapix Ce-64(Zschimmer Schwarz, Germany, 1. I wt% deposition cell. The suspension circulation system was not used relative to the powder mass)was added as dispersant. For com- in the other two configurations (3 and 4 of Table 1) where only parison, a suspension without platelets was also prepared. This 50 ml suspension was used to fill the EPD cell. Configuration suspension was magnetically stirred for 60 min, ultrasonicated 4 and 3 form respectively depositions along and in the oppo- in an ultrasonic bath(Branson 2510)for 15 min and magnetically site direction of the gravity force, in which the perforated top stirred for another 15 min electrode( Fig. 2)was replaced with a normal one. EPD was con- Density, Lotgering factor and texture index for different EPD configurations Green density [%] Sintered density [%I ening factor index Vertical Vertical stirred 594 0.49 18.32 Horizontal Bottom Flow through Horizontal 8.12 Horizontal Bottom Stagnant Stagnant1196 L. Zhang et al. / Journal of the European Ceramic Society 30 (2010) 1195–1202 Fig. 1. SEM image of (a) as-received alumina grade SM8 and (b) platelets. (Tosoh grade TZ-3Y) with a diameter of 5 mm were added to the polyethylene container to facilitate breaking the agglomer￾ates. Afterwards, platelets (5 wt% relative to the total amount of powder) were added to the ball-milled suspension, whilst n-butylamine (99.5% Acros Belgium, 3.4 vol% relative to the suspension volume) was added to negatively charge the particles and Dolapix Ce-64 (Zschimmer & Schwarz, Germany, 1.1 wt% relative to the powder mass) was added as dispersant. For com￾parison, a suspension without platelets was also prepared. This suspension was magnetically stirred for 60 min, ultrasonicated in an ultrasonic bath (Branson 2510) for 15 min and magnetically stirred for another 15 min. Fig. 2. EPD cell with horizontally positioned deposition electrode. Fig. 3. EPD cell with vertically positioned deposition electrode. To estimate the influence of the electric field force, gravity and hydrodynamic force on the alignment of the platelets, two different set-ups were used, i.e., with a vertical and horizontal EPD cell. Three configurations were studied in a slightly mod￾ified horizontal cell, as summarised in Table 1. The standard horizontal EPD cell is schematically presented in Fig. 2. In case of an applied suspension flow (configuration 2 in Table 1), a suspension was flown through the deposition cell by means of a suspension circulation system driven by a peristaltic pump. The distance between the flat disc shaped electrodes was 3.5 cm and the electrodes had a diameter of 3.7 cm. The suspension in the reservoir was stirred to avoid sedimentation. In addition, the flow-through system also decreases the sedimentation of the suspension in the cell with the fluid flow. Homogeneous deposits were made by pumping 200 ml suspension at 1 ml/s through the deposition cell. The suspension circulation system was not used in the other two configurations (3 and 4 of Table 1) where only 50 ml suspension was used to fill the EPD cell. Configuration 4 and 3 form respectively depositions along and in the oppo￾site direction of the gravity force, in which the perforated top electrode (Fig. 2) was replaced with a normal one. EPD was con￾Table 1 Density, Lotgering factor and texture index for different EPD configurations. Configuration Cell Deposition Suspension Green density [%] Sintered density [%] Lotgering factor Texture index 1 Vertical Vertical stirred 59.4 97.9 0.49 18.32 2 Horizontal Bottom Flow through 58.9 97.5 0.01 1.60 3 Horizontal Top Stagnant 62.7 99.7 0.21 8.12 4 Horizontal Bottom Stagnant 61.1 98.0 0.02 2.52 5 Vertical Vertical Stagnant – – 0.12 8.05