University College Dublin School of Chemical and Bioprocess Engineering An atmospheric pressure plasma jet system known as PlasmaStream TM has been used to deposit functional coatings on ceramic substrates. In this study the influence of plasma power and precursor flow rate on the properties of the deposited siloxane coatings are evaluated. Introduction Close-up view of the nozzle of the Dow Corning PlasmaStream TM system Influence of applied plasma power Acknowledgements Conclusion The financial support of Science Foundation Ireland and EU FP6 framework program is gratefully acknowledged. From this study it is concluded that the plasma power and the precursor flow rate has a significant effect on both the surface energy and roughness of the deposited coatings. Coatings with high surface energy was obtained under the conditions of high plasma power and low TEOS flow rate. This difference in coating chemistry is associated with the level of oxidation of the precursor in the plasma. The effect of process parameters on chemistry, roughness and morphology of the siloxane films deposited by an atmospheric plasma jet system R. Amsarani 1 , M. Rahman 1 , D.A. Mooney 1 , J.M.D. MacElroy 1 and D.P.Dowling 2 1 School of Chemical and Bioprocess Engineering, and 2 School of Electrical, Electronic & Mechanical Engineering, UCD, Dublin, Ireland. Deposition Conditions: Plasma Power : 10 to 90% He flow rate : 10 l/min O 2 flow rate : 100 ml/min Nozzle Height : 80 mm TEOS flow rate : 10 μl/min CNC speed : 25 mm/sec Number of passes over substrate: 3 Applied Plasma Power (%) 0 20 40 60 80 100 Water contact angle (°) 0 20 40 60 80 Surface energy (mN/m) 30 40 50 60 70 80 Contact angle (°) Surface energy (mN/m) Plasma Power (%) 0 20 40 60 80 100 Average Roughness R a (nm) 0 2 4 6 8 10 12 Coated Vycor glass Coated Si Wafer TEOS flow rate (μl/min) 0 10 20 30 40 50 60 Water contact angle (°) 0 10 20 30 40 50 Surface energy (mN/m) 50 55 60 65 70 Contact angle (°) Surface energy (mN/m) Influence of plasma power on average surface roughness (R a ) The surface energy of the coatings deposited at varying plasma power was determined using the contact angle measurement and found to increase from 33 to 69 mN/m with increasing power. This is attributed to an increase in the hydrophilic (SiO x type) content in the film. A further study of the influence of TEOS flow rates in the range 10 to 50 μl/min at 50% plasma power was carried out. Surface energy measurements indicate that the films deposited at lower TEOS flow rates were hydrophilic whereas the films deposited at higher flow rates were hydrophobic. Dependence of water contact angle/surface energy on TEOS flow rate. Siloxane film (50 nm thick) deposited on Vycor glass substrate at 10% plasma power Morphology by Scanning Electron Microscopy SEM images of the films deposited at a. 10% and b. 50% plasma power Dependence of water contact angle/surface energy on plasma power. Morphology by Atomic Force Microscopy Wavenumber (cm -1 ) 1000 1500 2000 2500 3000 3500 4000 Transmittance (%) 0.92 0.94 0.96 0.98 1.00 30% plasma power 50% plasma power 70% plasma power Wavenumber (cm-1) 1000 1100 1200 1300 Transmittance (%) 0.94 0.96 0.98 1.00 Film chemistry by Fourier Transform Infrared Spectroscopy The surface roughness of the deposited coating was found to increase with power as illustrated from the optical profilometer results. (a) (b) The presence of significant particulate formation is observed on the surface of the films which is due to excess gas-phase reactions. The FT-IR spectra of the films deposited at different plasma power (inset: the Si-O-Si stretching peak) The atmospheric pressure RF (17- 19 kHz) discharge is formed as He/O 2 gas mixture is passed between two electrodes. The plasma jet is moved over the surface to be coated using a computer numerical control (CNC) system. Tetraethyl orthosilicate (TEOS) precursor is fed as droplets into He/O 2 plasma using a pneumatic nebulizer to deposit nm thick siloxane coatings at varying plasma power and precursor flow rates. The increase in intensity of the Si-O-Si stretching frequency at 1060 cm -1 would indicate an increase in SiO x content. Influence of TEOS flow rate
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University College Dublin School of Chemical and Bioprocess Engineering
An atmospheric pressure plasma jet system known as PlasmaStreamTM has been used to deposit functional
coatings on ceramic substrates. In this study the influence of plasma power and precursor flow rate on the
properties of the deposited siloxane coatings are evaluated.
Introduction
Close-up view of the nozzle of the
Dow Corning PlasmaStreamTM system
Influence of applied plasma power
Acknowledgements
Conclusion
The financial support of Science Foundation Ireland and EU FP6 framework program is gratefully acknowledged.
From this study it is concluded that the plasma power and the precursor flow rate has a significant effect on both the surface energy and roughness
of the deposited coatings. Coatings with high surface energy was obtained under the conditions of high plasma power and low TEOS flow rate. This
difference in coating chemistry is associated with the level of oxidation of the precursor in the plasma.
The effect of process parameters on chemistry, roughness and morphology of the
siloxane films deposited by an atmospheric plasma jet system
R. Amsarani1, M. Rahman1, D.A. Mooney1, J.M.D. MacElroy1 and D.P.Dowling2
1School of Chemical and Bioprocess Engineering, and 2School of Electrical, Electronic & Mechanical Engineering, UCD, Dublin, Ireland.
Deposition Conditions:
Plasma Power : 10 to 90% He flow rate : 10 l/min
O2 flow rate : 100 ml/min Nozzle Height : 80 mm
TEOS flow rate : 10 µl/min CNC speed : 25 mm/sec
Number of passes over substrate: 3
Applied Plasma Power (%)
0 20 40 60 80 100
Wat
er c
on
tact
an
gle
(°)
0
20
40
60
80
Su
rface
en
erg
y (
mN
/m)
30
40
50
60
70
80
Contact angle (°)
Surface energy (mN/m)
Plasma Power (%)
0 20 40 60 80 100
Av
erag
e R
ou
gh
ness
Ra
(nm
)
0
2
4
6
8
10
12
Coated Vycor glass
Coated Si Wafer
TEOS flow rate (µl/min)
0 10 20 30 40 50 60
Wat
er c
on
tact
an
gle
(°)
0
10
20
30
40
50
Su
rfac
e en
erg
y (
mN
/m)
50
55
60
65
70
Contact angle (°)
Surface energy (mN/m)
Influence of plasma power on
average surface roughness (Ra)
The surface energy of the coatings deposited at varying plasma power
was determined using the contact angle measurement and found to
increase from 33 to 69 mN/m with increasing power. This is attributed to
an increase in the hydrophilic (SiOx type) content in the film.
A further study of the influence of TEOS flow rates in the range 10 to
50 µl/min at 50% plasma power was carried out. Surface energy
measurements indicate that the films deposited at lower TEOS flow
rates were hydrophilic whereas the films deposited at higher flow rates
were hydrophobic.
Dependence of water contact angle/surface energy on TEOS flow rate.
Siloxane film (50 nm thick) deposited on Vycor
glass substrate at 10% plasma power
Morphology by Scanning Electron Microscopy
SEM images of the films deposited at a. 10% and b. 50% plasma power
Dependence of water contact angle/surface
energy on plasma power.
Morphology by Atomic Force Microscopy
Wavenumber (cm-1
)
1000 1500 2000 2500 3000 3500 4000
Tra
nsm
itta
nce
(%)
0.92
0.94
0.96
0.98
1.00
30% plasma power
50% plasma power
70% plasma power
Wavenumber (cm-1
)
1000 1100 1200 1300
Tra
nsm
itta
nce (
%)
0.94
0.96
0.98
1.00
Film chemistry by Fourier Transform Infrared Spectroscopy
The surface roughness of the deposited coating was found to increase
with power as illustrated from the optical profilometer results.
(a) (b)
The presence of significant particulate formation is observed on the
surface of the films which is due to excess gas-phase reactions.
The FT-IR spectra of the films deposited at different plasma power (inset: the Si-O-Si
stretching peak)
The atmospheric pressure RF (17- 19 kHz) discharge is formed as He/O2 gas mixture is passed between two
electrodes. The plasma jet is moved over the surface to be coated using a computer numerical control (CNC)
system. Tetraethyl orthosilicate (TEOS) precursor is fed as droplets into He/O2 plasma using a pneumatic
nebulizer to deposit nm thick siloxane coatings at varying plasma power and precursor flow rates.
The increase in intensity of the Si-O-Si stretching frequency at 1060 cm-1
would indicate an increase in SiOx content.
Influence of TEOS flow rate
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