1. 1 Application of constant current pulse to suppress bubble incorporation and control deposit morphology during aqueous electrophoretic deposition (EPD) Journal of the European Ceramic Society 29 (2009) 1837–1845 L. Besra, T. Uchikoshi*, T.S. Suzuki, Y. Sakka Advisor : Prof. S.C.Wang Advisee : Jyun-Jia Huang

2. 2 Outline Introduction Experimental Results and discussion Conclusions Future work

3. 3 Introduction ＋ － ＋ － ＋ EPD process Continuous Voltage pulse

4. 4 Experimental DI Water α- alumina 200 nm 5 vol.% EPD dried at room temperature stereomicroscope ultrasonic bath for 10 min EPD 參數 applied voltage = constant current pulse cathode ： Pd anode ： Steel ( 2 cm×5 cm×0.4mm ) distance = 20 mm deposition time ≧ 3 min pH ： 4.5 Fig. 1 Schematic of constant current pulse of 50% duty cycle.

5. 5 Results and discussion

6. 6 Fig. 2. Deposit yield as a function of applied current during continuous DC EPD. Fig. 3. Surface morphology of deposits obtained by continuous DC EPD in constant current mode.

7. 7 Fig. 4. Variation in voltage with time during constant current continuous DC EPD of alumina suspension at different applied currents. Fig. 8. Variation in voltage with time during pulsed constant current EPD.

8. 8 Fig. 6. Surface morphology of deposits obtained by pulsed DC EPD in constant current mode (a) applied current: 0.004 A, (b) applied current: 0.006A. Fig. 5. Deposit yield as a function of pulse width during pulsed DC EPD at constant current mode.

9. 9 Fig. 7. Pulse-width vs. applied voltage diagram showing the window (hatched region) in which bubble-free deposits are obtained during pulsed DC EPD at constant current mode.

10. 10 Fig. 9. Influence of duty cycle on surface morphology of deposits obtained by constant current pulsed EPD of 5 vol% alumina suspension.

11. 11 Conclusions Application of a pulse current of suitable width enables controlling the amount of bubble incorporation and obtaining smooth, bubble-free deposit by electrophoretic deposition. For any applied current, there is no deposition at pulse widths smaller than the lower limit of the window. At pulse widths above the upper limit of the window, the deposits invariably contained bubbles in them. It is more convenient and practicable to control the pulse EPD for obtaining bubble- free deposit at lower applied currents but at the expense of deposit yield.

12. 12 THANK YOU FOR YOUR ATTENTION ！