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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
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Outline
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•
•
•
•
Introduction
Experimental
Results and discussion
Conclusions
Future work
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Introduction
－
＋
＋
pulse
－
＋
Continuous Voltage
EPD process
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Experimental
α-alumina
EPD 參數
200 nm
5 vol.%
DI Water
ultrasonic bath for 10 min
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
EPD
dried at room temperature
Fig. 1 Schematic of constant current
pulse of 50% duty cycle.
stereomicroscope
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Results and discussion
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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 .
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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.
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Fig. 5. Deposit yield as a function of pulse
width during pulsed DC EPD at
constant current mode .
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 .
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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 .
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Fig. 9. Influence of duty cycle on surface morphology of deposits obtained by
constant current pulsed EPD of 5 vol% alumina suspension.
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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 bubblefree deposit at lower applied currents but at the expense of deposit yield.
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THANK YOU FOR YOUR
ATTENTION！
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