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Electrical Discharge Machining of
Carbon Nanofiber for Uniform
Field Emission
報告者：陳思懿
報告日期：13/10/2010
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Outline
• INTRODUCTION
• EXPERIMENTAL SYSTEM
• MACHINING OF CNFS
• PLANERIZATION OF CNFSFOR
UNIFORM FIELD EMISSION
• CONCLUSIONS
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Introduction
Electrical discharging machining (EDM) of carbon nano fiber
(CNF) is introduced. CNF has been investigated as an emitter
for field emission display (FED). For the uniform field emission,
uneven CNFs need to be machined to uniform height. For
theplanarization of CNFs, EDM was used. EDM was conducted
in air, unlike conventional EDM, to prevent the contamination of
CNFs. For the uniformity of the machined surface,machining
characteristics were investigated with applying different
capacitance and voltage. With this method,the uniformity of
field emission of CNFs was improved.
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EXPERIMENTAL SYSTEM
Figure 1:
(a) schematics of EDM process for CNF
planarization
(b) photo of the EDM system
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MACHINING OF CNFS 1/7
EDM of measurement
for SEM images
(a)CNF
(B)EDMed CNF
Figure2:Carbon nano fibers before and
after EDM
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MACHINING OF CNFS 2/7
Figure3: The change of machining gap according
to applied voltage and electrode diameter.
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MACHINING OF CNFS 3/7
Machined of surface for SEM images
(a)40V
(c)100V
(b)80V
(d)150V
Figure 4: Machined surface according to
voltage.
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MACHINING OF CNFS 4/7
Machining gap with capacitance of measurement
Figure 5:The change of machining gap according to
capacitance
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MACHINING OF CNFS 5/7
The electrode of surface for SEM images
Figure 6:CNFs attached to a tool electrode
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MACHINING OF CNFS 6/7
(a)Stray capacitance
(b)10,000 pF
Figure7: Machined surface according
to capacitance.
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PLANERIZATION OF CNFS FOR
UNIFORM FIELD EMISSION 1/3
CNT films surface by SEM images
(a)
(b)
Figure 9: SEM images of CNF
films :(a)before and(b), (c)after the
EDM process.
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PLANERIZATION OF CNFS FOR
UNIFORM FIELD EMISSION 2/3
Raman spectra to analysis CNT films
SP2 G Band
SP3 D Band
Figure 10:Raman spectra of CNF substrate
before and after EDM
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PLANERIZATION OF CNFS FOR
UNIFORM FIELD EMISSION 3/3
The emission image by CNFs application
Figure 11: (a),(b)before and (c),(d)after the
EDM treatment .
(a)and(c),(b)and(d)were taken at
the same electric field of 2.3 V/μm
,2.7 V/µm, respectively.
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Conclusion
1.The machining of CNFs by EDM was investigated to improve the
uniformity of field emission.
2.From the experiments, stray capacitance and 80 – 100 V are
suitable for the uniform machining surface.
3.Since debris can deteriorate the field emission property. The
machining condition which produces small discharging energy is
useful to reduce debris.
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Thanks for your attention！！
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