L Besra, M. Liu Progress in Materials Science 52(2007)1-61 10 Applied voltage Fig. 6. Weight of deposited hydroxyapatite on Ti6Al4V substrate versus applied voltage for different deposition durations:(a)30 s and (b)120 s[431 fast that they cannot find enough time to sit in their best positions to form a close-packed structure. Finally, in high field situations, lateral motion of the particles once deposited also are restricted on the surface of the already deposited layer, because higher applied potential exerts more pressure on particle flux and movement, the applied field affects the deposition rate and the structure of the deposit. Negishi et al. [33]observed that the current density of n-propanol solvent in absence of any powder, were proportional to applied voltage and it tend to unstable with increasing applied voltages(Fig. 7). Such stability data serves as a good guideline for deciding the deposition parameters and consequently the quality of deposit formed by EPD. It is con idered that the unstable current density influences the quality of deposition morphology 300V 100V Time(min) Fig. 7. Stability of current density of n-propanol for different applied voltages [33]fast that they cannot find enough time to sit in their best positions to form a close-packed structure. Finally, in high field situations, lateral motion of the particles once deposited, also are restricted on the surface of the already deposited layer, because higher applied potential exerts more pressure on particle flux and movement, the applied field affects the deposition rate and the structure of the deposit. Negishi et al. [33] observed that the current density of n-propanol solvent in absence of any powder, were proportional to applied voltage and it tend to unstable with increasing applied voltages (Fig. 7). Such stability data serves as a good guideline for deciding the deposition parameters and consequently the quality of deposit formed by EPD. It is con￾sidered that the unstable current density influences the quality of deposition morphology. Fig. 6. Weight of deposited hydroxyapatite on Ti6Al4V substrate versus applied voltage for different deposition durations: (a) 30 s and (b) 120 s [43]. Fig. 7. Stability of current density of n-propanol for different applied voltages [33]. 12 L. Besra, M. Liu / Progress in Materials Science 52 (2007) 1–61