Effects of Operating Conditions on Thin Film Deposition Performance in Air Atomizing Spray Pyrolysis
ASME 2010 International Manufacturing Science and Engineering Conference, Volume 1, 2010
ABSTRACT Thin films have been finding more and more applications in electronics, optical devices,... more ABSTRACT Thin films have been finding more and more applications in electronics, optical devices, and energy conversion and storage devices, to name a few. As one of the most promising thin film deposition techniques, air atomizing spray pyrolysis, which uses compressed air to disrupt the liquid stream into droplets, has been favored in scientific and engineering communities. However, the effects of operating conditions such as liquid flow rate, atomizing air pressure, fan air pressure, and air gap on the geometric properties of deposited thin film are still not systematically studied. The objective of this study is to experimentally investigate the effects of air spraying operating conditions on the surface roughness and thickness of deposited zinc oxide (ZnO) thin film. It is found 1) The surface roughness increases with the liquid flow rate, but decreases with the atomizing air pressure, fan air pressure, and air gap; 2) The surface roughness decreases along both the X and Y directions under any given operating condition; 3) The thickness increases with the liquid flow rate and the atomizing air pressure, but decreases with the fan air pressure and the air gap; and 4) The thickness generally changes differently along the X and Y directions. Along the X direction, it decreases monotonically; however, along the Y direction, it increases first then decreases as in a saddle shape. While ZnO film deposition is studied, it is expected that the above conclusions may be applicable in air spraying other materials.
ASME 2009 International Manufacturing Science and Engineering Conference, Volume 2, 2009
Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. ... more Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, cell injury due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when vaporization and/or optical breakdown of coating materials is/are not available. It is found that a bipolar pressure pair, with peak magnitudes on the order of 1 MPa or higher, has been developed within a finite thin coating medium. Shorter duration laser pulses lead to higher thermoelastic stresses. This study will help to understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.
1Dept. Ophthalmology, Moran Eye Center, University of Utah; 2Dept. Ophthalmology, Nagoya University, Graduate School of Medicine. Corresponding author: BW Jones University of Utah, Moran Eye Center, 65 Mario Capecchi Dr., Salt Lake City 84132 UT
The effect of clay dispersion on the crystallization behavior of isotactic polypropylene (iPP)-ba... more The effect of clay dispersion on the crystallization behavior of isotactic polypropylene (iPP)-based nanocomposites is reported. The T m 0 of the materials was calculated by the method proposed by Marand, the kinetics of crystallization was evaluated by the Avrami analysis and also the Hoffman-Lauritzen theory of crystallization regimes was applied. Montmorillonite was found to depress T m 0 , to enhance the rate of crystallization and to ease the chain folding of macromolecules. These effects were magnified if clay was exfoliated, rather than intercalated.
This paper proposes laser sintering of screenprinted silver grids, which is compatible with low t... more This paper proposes laser sintering of screenprinted silver grids, which is compatible with low temperature surface passivation materials such as intrinsic hydrogenated amorphous silicon and has the potential of fabricating high efficiency solar cells at a low cost. It was found that a nanosecond pulsed laser (! = 532 nm) can locally and controllably fire silver paste through SiNx without punching through the underneath phosphorus-diffused emitter. A low temperature belt firing prior to laser sintering is helpful for improving the quality of laser sintering. Laser sintered cells reached 17.3% cell efficiency on 239 cm 2 cell area.
Effects of Operating Conditions on Thin Film Deposition Performance in Air Atomizing Spray Pyrolysis
ASME 2010 International Manufacturing Science and Engineering Conference, Volume 1, 2010
ABSTRACT Thin films have been finding more and more applications in electronics, optical devices,... more ABSTRACT Thin films have been finding more and more applications in electronics, optical devices, and energy conversion and storage devices, to name a few. As one of the most promising thin film deposition techniques, air atomizing spray pyrolysis, which uses compressed air to disrupt the liquid stream into droplets, has been favored in scientific and engineering communities. However, the effects of operating conditions such as liquid flow rate, atomizing air pressure, fan air pressure, and air gap on the geometric properties of deposited thin film are still not systematically studied. The objective of this study is to experimentally investigate the effects of air spraying operating conditions on the surface roughness and thickness of deposited zinc oxide (ZnO) thin film. It is found 1) The surface roughness increases with the liquid flow rate, but decreases with the atomizing air pressure, fan air pressure, and air gap; 2) The surface roughness decreases along both the X and Y directions under any given operating condition; 3) The thickness increases with the liquid flow rate and the atomizing air pressure, but decreases with the fan air pressure and the air gap; and 4) The thickness generally changes differently along the X and Y directions. Along the X direction, it decreases monotonically; however, along the Y direction, it increases first then decreases as in a saddle shape. While ZnO film deposition is studied, it is expected that the above conclusions may be applicable in air spraying other materials.
ASME 2009 International Manufacturing Science and Engineering Conference, Volume 2, 2009
Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. ... more Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, cell injury due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when vaporization and/or optical breakdown of coating materials is/are not available. It is found that a bipolar pressure pair, with peak magnitudes on the order of 1 MPa or higher, has been developed within a finite thin coating medium. Shorter duration laser pulses lead to higher thermoelastic stresses. This study will help to understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.
1Dept. Ophthalmology, Moran Eye Center, University of Utah; 2Dept. Ophthalmology, Nagoya University, Graduate School of Medicine. Corresponding author: BW Jones University of Utah, Moran Eye Center, 65 Mario Capecchi Dr., Salt Lake City 84132 UT
The effect of clay dispersion on the crystallization behavior of isotactic polypropylene (iPP)-ba... more The effect of clay dispersion on the crystallization behavior of isotactic polypropylene (iPP)-based nanocomposites is reported. The T m 0 of the materials was calculated by the method proposed by Marand, the kinetics of crystallization was evaluated by the Avrami analysis and also the Hoffman-Lauritzen theory of crystallization regimes was applied. Montmorillonite was found to depress T m 0 , to enhance the rate of crystallization and to ease the chain folding of macromolecules. These effects were magnified if clay was exfoliated, rather than intercalated.
This paper proposes laser sintering of screenprinted silver grids, which is compatible with low t... more This paper proposes laser sintering of screenprinted silver grids, which is compatible with low temperature surface passivation materials such as intrinsic hydrogenated amorphous silicon and has the potential of fabricating high efficiency solar cells at a low cost. It was found that a nanosecond pulsed laser (! = 532 nm) can locally and controllably fire silver paste through SiNx without punching through the underneath phosphorus-diffused emitter. A low temperature belt firing prior to laser sintering is helpful for improving the quality of laser sintering. Laser sintered cells reached 17.3% cell efficiency on 239 cm 2 cell area.
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