L Zhang et al. / Journal of the European Ceramic Society 30(2010)1195-1202 Fig. 11. SEM micrograph revealing the microstructure of a perpendicularly cross-sectioned sintered ceramic after EPD from a stagnant suspension in a face. Platelet alignment is substantially better when stirring the over, stirring completely inhibited suspension sedimentation. As a result, the magnetically stirred vertical EPD cell(configura tion 1)gives the best texture, as shown in Table 1. It should also be noted that the magnitude of the hydrodynamic force in the two EPD cells is different. The suspension flows through the horizontal cell with a volume of about 50ml at 1 ml/s. In the vertical cell, the magnetic stirrer stirred 50 ml of suspension at c250rpm. The hydrodynamic force is therefore substantially lower in the horizontal cell. the influence of a fluid fow or platelet orientation in the horizontal cell is limited as shown by the comparable Lotgering factors(0.01 versus 0.02)and tex ture indexes(1.60 versus 2. 52)in Table 1. In the vertical cell, the shear force applied by the fluid is an important factor for platelet Fig. 10. Flow pattern during EPD(a)in a cross-sectioned horizontal cell with orientation, as indicated by the significant increase in Lotgering suspension flowing through and(b) top view of the flow pattern during EPD in factor from 0. 12 to 0.49 and texture index from 8.05 to 18.32, a vertical cell with magnetic stirring. The deposition electrode is marked by the as induced by the hydrodynamic force 5. Conclusions 43. Influence of the hydrodynamic force Platelet template particles used for templated grain growth When stirring the suspension or generating a suspension d be aligned during the electrophoretic deposition process flow in the EPD cell, the generated hydrodynamic force in the The influence of the electric field force, gravity and hydrody- neighbourhood of the deposition electrode will influence the namic force are studied in a vertical and horizontal deposition deposition process. The hydrodynamic force in the horizontal cell. The electric field force orients the c-axis of the platelets par- cell is different than in the vertical cell, as schematically pre- allel to the electric field force direction. Powder sedimentation sented in Fig. 10. The basal plane of the platelets would be induced by gravity however is detrimental for platelet alignment aligned along the fluid direction in order to minimize the drag- in the deposit. The hydrodynamic force aligns the basal plane ging force. As shown in Fig. 10(a), the hydrodynamic force is parallel to the suspension flow direction. The ceramics processed not parallel to the electrode surface in the horizontal cell, which under different EPD configurations result in a difterent degree of may interfere with the alignment of the platelets. The platelets texture, implying that the EPD deposition cell configuration is are indeed not well aligned as shown in Fig. 6(b). In the vertical a critical factor for the platelet template alignment. The highest cell,however, the shear force applied by the fluid flow is almost (00 1)alumina texture, with a Lotgering factor of 0. 49 and tex- parallel to the electrode surface, as illustrated in Fig. 10(b). In ture index of 18.32, was obtained after templated grain growth this case, the hydrodynamic force assists in aligning the basal of the deposits obtained from a vertical EPD cell configuration plane of the platelets parallel to the deposition electrode suI with a stirred suspension.L. Zhang et al. / Journal of the European Ceramic Society 30 (2010) 1195–1202 1201 Fig. 10. Flow pattern during EPD (a) in a cross-sectioned horizontal cell with suspension flowing through and (b) top view of the flow pattern during EPD in a vertical cell with magnetic stirring. The deposition electrode is marked by the arrow at the bottom. 4.3. Influence of the hydrodynamic force When stirring the suspension or generating a suspension flow in the EPD cell, the generated hydrodynamic force in the neighbourhood of the deposition electrode will influence the deposition process. The hydrodynamic force in the horizontal cell is different than in the vertical cell, as schematically pre￾sented in Fig. 10. The basal plane of the platelets would be aligned along the fluid direction in order to minimize the drag￾ging force. As shown in Fig. 10(a), the hydrodynamic force is not parallel to the electrode surface in the horizontal cell, which may interfere with the alignment of the platelets. The platelets are indeed not well aligned as shown in Fig. 6(b). In the vertical cell, however, the shear force applied by the fluid flow is almost parallel to the electrode surface, as illustrated in Fig. 10(b). In this case, the hydrodynamic force assists in aligning the basal plane of the platelets parallel to the deposition electrode sur￾Fig. 11. SEM micrograph revealing the microstructure of a perpendicularly cross-sectioned sintered ceramic after EPD from a stagnant suspension in a vertical cell. face. Platelet alignment is substantially better when stirring the suspension (Fig. 5 (b)) than without stirring (Fig. 11). More￾over, stirring completely inhibited suspension sedimentation. As a result, the magnetically stirred vertical EPD cell (configura￾tion 1) gives the best texture, as shown in Table 1. It should also be noted that the magnitude of the hydrodynamic force in the two EPD cells is different. The suspension flows through the horizontal cell with a volume of about 50 ml at 1 ml/s. In the vertical cell, the magnetic stirrer stirred 50 ml of suspension at ∼250 rpm. The hydrodynamic force is therefore substantially lower in the horizontal cell. The influence of a fluid flow on platelet orientation in the horizontal cell is limited, as shown by the comparable Lotgering factors (0.01 versus 0.02) and tex￾ture indexes (1.60 versus 2.52) in Table 1. In the vertical cell, the shear force applied by the fluid is an important factor for platelet orientation, as indicated by the significant increase in Lotgering factor from 0.12 to 0.49 and texture index from 8.05 to 18.32, as induced by the hydrodynamic force. 5. Conclusions Platelet template particles used for templated grain growth could be aligned during the electrophoretic deposition process. The influence of the electric field force, gravity and hydrody￾namic force are studied in a vertical and horizontal deposition cell. The electric field force orients the c-axis of the platelets par￾allel to the electric field force direction. Powder sedimentation induced by gravity however is detrimental for platelet alignment in the deposit. The hydrodynamic force aligns the basal plane parallel to the suspension flow direction. The ceramics processed under different EPD configurations result in a different degree of texture, implying that the EPD deposition cell configuration is a critical factor for the platelet template alignment. The highest (0 0 1) alumina texture, with a Lotgering factor of 0.49 and tex￾ture index of 18.32, was obtained after templated grain growth of the deposits obtained from a vertical EPD cell configuration with a stirred suspension