L Besra, M. Liu/Progress in Materials Science 52(2007)1-61 330 270 240 (c)100V 180 120 b)60V 60 (a)20V Fig. 4. Relationship between deposit thickness and time of deposition for Zno coatings on copper electrode at different applied potential [42]. 0.20 0.15 0.10 100150200250300 Fig. 5. Current density versus deposition time for deposition of hydroxyapatite at different applied voltages:(a) 50v;(b)100v;(c)200V[43y 3. 2.2. Applied volt Normally the amount of deposit increases with increase in applied potential. Fig. 6 shows the weight of deposited hydroxyapatite on Ti6Al4V substrate from its suspension in isopropyl alcohol. Although powders can be deposited more quickly if greater applie fields are used, the quality of the deposit can suffer. Basu et al. [41] found that more uni- form films are deposited at moderate applied fields(25-100 V/cm), whereas the film qual- ity deteriorates if relatively higher applied fields(>100 V/cm)are used. because the formation of particulate film on the electrode is a kinetic phenomenon, the accumulation rate of the particles influences their packing behaviour in coating. For a higher applied field, which may cause turbulence in the suspension, the coating may be disturbed by flows in the surrounding medium, even during its deposition. In addition, particles can move so3.2.2. Applied voltage Normally the amount of deposit increases with increase in applied potential. Fig. 6 shows the weight of deposited hydroxyapatite on Ti6Al4V substrate from its suspension in isopropyl alcohol. Although powders can be deposited more quickly if greater applied fields are used, the quality of the deposit can suffer. Basu et al. [41] found that more uni￾form films are deposited at moderate applied fields (25–100 V/cm), whereas the film qual￾ity deteriorates if relatively higher applied fields (>100 V/cm) are used. Because the formation of particulate film on the electrode is a kinetic phenomenon, the accumulation rate of the particles influences their packing behaviour in coating. For a higher applied field, which may cause turbulence in the suspension, the coating may be disturbed by flows in the surrounding medium, even during its deposition. In addition, particles can move so Fig. 4. Relationship between deposit thickness and time of deposition for ZnO coatings on copper electrode at different applied potential [42]. Fig. 5. Current density versus deposition time for deposition of hydroxyapatite at different applied voltages: (a) 50 V; (b) 100 V; (c) 200 V [43]. L. Besra, M. Liu / Progress in Materials Science 52 (2007) 1–61 11