The Experts below are selected from a list of 1332 Experts worldwide ranked by ideXlab platform
Marcio S. Carvalho - One of the best experts on this subject based on the ideXlab platform.
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Mapping Slide Coating Window with Flow Visualization
2015Co-Authors: Kristianto Tjiptowidjojo, Wieslaw J. Suszynski, Marcio S. CarvalhoAbstract:The complete understanding of the mechanisms of Coating processes failures is usually the result of detailed flow visualization and theoretical modeling. In slot Coating process, these tools have been used to successfully describe and determine the operating parameters of bead break-up at low-vacuum, high vacuum and low flow limit for Newtonian and non-Newtonian liquids. The Coating window of Slide Coating is not as well understood. The currently best available information appears to be Hens & Van Abbenyen (1997) and Chen (1992). They describe some of the Coating defects that define the boundary of the operability window of the process. However, flow mechanisms associated with the different defects have not been addressed. One reason is that the break-up modes have not been perceptively viewed through a transparent back-up roll in a systematic flow visualization study. In this work, we are extending Romero et al (2004) analysis of slot Coating to Slide Coating. We are probing the bead breakup mechanisms with the aid of through-the-roll viewing of the bead at low-vacuum, high-vacuum, and low-flow limits. We are investigating the flow states that lie beyond the operability limits and operating parameters, such as web speed, vacuum pressure, gap height and Slide inclination, which set them u
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Uncovering Slide Coating Window with Theoretical Modeling
2015Co-Authors: Kristianto Tjiptowidjojo, Marcio S. CarvalhoAbstract:Slide Coating is a method used for rapidly depositing multilayer of Coating onto a moving substrate or web simultaneously. This method is commonly used in the manufacturing of photographic products, magnetic recording media, and optical films. Slide Coating is a premetered Coating method, in which the thickness of the Coating is set by the liquid flow rate and web speed only and independent of the other operating parameters, making it the method of choice for precision Coating. However, the nature of the flow in the Coating bead and therefore the uniformity of the liquid layer deposited on the substrate can be affected by the other operating parameters. The region in the operating parameters of a Coating process where the applied liquid layer is adequately uniform is referred to the Coating window and that is the focus of this study. Fundamentals of Slide Coating window, even for single-layer, are not completely understood. Incomplete Slide Coating windows with some of the modes of Coating bead breakdown are described in Chen (1992) and Hens and van Abbenyen (1997). Mechanisms, however, have not been addressed and the effects of die-lip geometry have not been explored. In contrast, slot Coating window is much better understood, mechanisms of bead breakdown have been identified (Romero et al 2004) and the effects of die-lip geometry have been studied (Gates 1999). Our goa
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operability limits of Slide Coating
Chemical Engineering Science, 2011Co-Authors: Kristianto Tjiptowidjojo, Marcio S. CarvalhoAbstract:Abstract Slide Coating is one of the pre-metered methods used for high precision single and multilayer Coatings. The thickness of each liquid layers is set by the flow rate and web speed only and it is independent of other process parameters. The uniformity of the deposited layer, however, is affected by the operating conditions. In the design of Coating processes, it is crucial to know the set of conditions at which the deposited layer is adequately uniform, i.e. to define the operability window of the process. We developed a theoretical model of Slide Coating flow by solving the full two-dimensional Navier–Stokes equations and used it to uncover the mechanisms of Coating bead breakdown at low vacuum, high vacuum, and low flow limits. With full understanding of the bead breakup processes, we then constructed a theoretical Coating window as a function of Coating thickness, web speed, and applied vacuum. A simple stability criterion was used to predict the onset of ribbing instability and deployed to add the onset of ribbing limit inside the Coating window.
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viscocapillary model of Slide Coating effect of operating parameters and range of validity
Aiche Journal, 2009Co-Authors: K Tjiptowidjojo, Marcio S. CarvalhoAbstract:Slide Coating is one of the premetered high-precision Coating methods. The layer thickness is set by the flow rate and web speed. The uniformity of the layer, however, can be affected by other operating conditions. Modeling the flow in the Coating bead is necessary in developing the range of operability conditions where the layer is adequately uniform. Lubrication and viscocapillary models have been used to describe the flow and some of the operability limits of different Coating processes. However, the available models of Slide Coating were developed with adhoc hypotheses that compromise their accuracy. We present a critical review of the available viscocapillary models and proposed changes to improve its range of applicability. The accuracy of the model is tested by comparing its predictions to the solution of the full two-dimensional Navier-Stokes equation. The model is valid at low capillary and Reynolds number regime and at low gap-to-wet thickness ratio. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Kiyoshi Yase - One of the best experts on this subject based on the ideXlab platform.
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investigation of Slide Coating method for poly 3 hexylthiophene field effect transistors
Japanese Journal of Applied Physics, 2010Co-Authors: Makoto Karakawa, Masayuki Chikamatsu, Yuji Yoshida, Makoto Oishi, Reiko Azumi, Kiyoshi YaseAbstract:Slide-Coating method is relatively a new thin-film fabrication method using the shear force between two substrates. We have fabricated poly(3-hexylthiophene) (P3HT) thin-films by this method. The organic field-effect transistors (OFETs) based on thus fabricated P3HT films exhibit good performance in field-effect mobility. Ultraviolet–visible (UV–vis) absorption spectra, X-ray diffraction patterns and polarizing microscopy show an in-plane anisotropic structure of the film. The good OFET performance would be assigned to such structure of the films. This thin-film fabrication method was revealed to be an effective method to fabricate a well-ordered structure of P3HT films and their OFETs.
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high performance poly 3 hexylthiophene field effect transistors fabricated by a Slide Coating method
Applied Physics Express, 2008Co-Authors: Makoto Karakawa, Masayuki Chikamatsu, Yuji Yoshida, Makoto Oishi, Reiko Azumi, Kiyoshi YaseAbstract:Highly oriented thin-films of poly(3-hexylthiophene) (P3HT) have been successfully fabricated by Slide-Coating method, in which the chloroform solution is sandwiched between a Si wafer and a Slide glass, and followed by slow drawing of the Si wafer with respect to the Slide glass. The performance of this organic field-effect transistor (OFET) based on the P3HT film exhibit high-performance of up to 0.056 cm2 V-1 s-1 in FET mobility. This simple solution process is an effective method to fabricate the well-ordered structure of the P3HT film and its OFETs.
Makoto Karakawa - One of the best experts on this subject based on the ideXlab platform.
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investigation of Slide Coating method for poly 3 hexylthiophene field effect transistors
Japanese Journal of Applied Physics, 2010Co-Authors: Makoto Karakawa, Masayuki Chikamatsu, Yuji Yoshida, Makoto Oishi, Reiko Azumi, Kiyoshi YaseAbstract:Slide-Coating method is relatively a new thin-film fabrication method using the shear force between two substrates. We have fabricated poly(3-hexylthiophene) (P3HT) thin-films by this method. The organic field-effect transistors (OFETs) based on thus fabricated P3HT films exhibit good performance in field-effect mobility. Ultraviolet–visible (UV–vis) absorption spectra, X-ray diffraction patterns and polarizing microscopy show an in-plane anisotropic structure of the film. The good OFET performance would be assigned to such structure of the films. This thin-film fabrication method was revealed to be an effective method to fabricate a well-ordered structure of P3HT films and their OFETs.
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high performance poly 3 hexylthiophene field effect transistors fabricated by a Slide Coating method
Applied Physics Express, 2008Co-Authors: Makoto Karakawa, Masayuki Chikamatsu, Yuji Yoshida, Makoto Oishi, Reiko Azumi, Kiyoshi YaseAbstract:Highly oriented thin-films of poly(3-hexylthiophene) (P3HT) have been successfully fabricated by Slide-Coating method, in which the chloroform solution is sandwiched between a Si wafer and a Slide glass, and followed by slow drawing of the Si wafer with respect to the Slide glass. The performance of this organic field-effect transistor (OFET) based on the P3HT film exhibit high-performance of up to 0.056 cm2 V-1 s-1 in FET mobility. This simple solution process is an effective method to fabricate the well-ordered structure of the P3HT film and its OFETs.
Kristianto Tjiptowidjojo - One of the best experts on this subject based on the ideXlab platform.
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process model for multilayer Slide Coating of polymer electrolyte membrane fuel cells
Journal of Coatings Technology and Research, 2021Co-Authors: Kristianto Tjiptowidjojo, Janghoon Park, Scott A Mauger, Michael Ulsh, Peter Randall SchunkAbstract:Slide Coating is a precision method suitable for depositing multiple liquid-film layers simultaneously. Originally developed in the photographic film industry, it has been deployed for manufacturing of other products that benefit from multilayer Coatings. One emerging application is the manufacture of polymer electrolyte membrane fuel cells (PEMFCs), which are used to produce electricity through electrochemical reactions of hydrogen and oxygen gas. The membrane-electrode assembly (MEA), in which key electrochemical reactions occur, consists of three layers that are typically deposited separately in serial fashion and then laminated together to form the three-layer MEA, i.e., three sequential steps of coat and dry. Adapting the process to simultaneous, multilayer Slide Coating of all three layers will save equipment cost and space while minimizing possible exposure to contaminants during transition between the steps. We are developing a three-layer Slide Coating model to aid the manufacturing process design of PEMFC. The model accounts for rheology of each layer, which typically exhibit shear thinning behavior. Model predictions are used to investigate simultaneous coatability of catalyst inks and to determine the best layer-by-layer ink selection.
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Mapping Slide Coating Window with Flow Visualization
2015Co-Authors: Kristianto Tjiptowidjojo, Wieslaw J. Suszynski, Marcio S. CarvalhoAbstract:The complete understanding of the mechanisms of Coating processes failures is usually the result of detailed flow visualization and theoretical modeling. In slot Coating process, these tools have been used to successfully describe and determine the operating parameters of bead break-up at low-vacuum, high vacuum and low flow limit for Newtonian and non-Newtonian liquids. The Coating window of Slide Coating is not as well understood. The currently best available information appears to be Hens & Van Abbenyen (1997) and Chen (1992). They describe some of the Coating defects that define the boundary of the operability window of the process. However, flow mechanisms associated with the different defects have not been addressed. One reason is that the break-up modes have not been perceptively viewed through a transparent back-up roll in a systematic flow visualization study. In this work, we are extending Romero et al (2004) analysis of slot Coating to Slide Coating. We are probing the bead breakup mechanisms with the aid of through-the-roll viewing of the bead at low-vacuum, high-vacuum, and low-flow limits. We are investigating the flow states that lie beyond the operability limits and operating parameters, such as web speed, vacuum pressure, gap height and Slide inclination, which set them u
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Uncovering Slide Coating Window with Theoretical Modeling
2015Co-Authors: Kristianto Tjiptowidjojo, Marcio S. CarvalhoAbstract:Slide Coating is a method used for rapidly depositing multilayer of Coating onto a moving substrate or web simultaneously. This method is commonly used in the manufacturing of photographic products, magnetic recording media, and optical films. Slide Coating is a premetered Coating method, in which the thickness of the Coating is set by the liquid flow rate and web speed only and independent of the other operating parameters, making it the method of choice for precision Coating. However, the nature of the flow in the Coating bead and therefore the uniformity of the liquid layer deposited on the substrate can be affected by the other operating parameters. The region in the operating parameters of a Coating process where the applied liquid layer is adequately uniform is referred to the Coating window and that is the focus of this study. Fundamentals of Slide Coating window, even for single-layer, are not completely understood. Incomplete Slide Coating windows with some of the modes of Coating bead breakdown are described in Chen (1992) and Hens and van Abbenyen (1997). Mechanisms, however, have not been addressed and the effects of die-lip geometry have not been explored. In contrast, slot Coating window is much better understood, mechanisms of bead breakdown have been identified (Romero et al 2004) and the effects of die-lip geometry have been studied (Gates 1999). Our goa
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operability limits of Slide Coating
Chemical Engineering Science, 2011Co-Authors: Kristianto Tjiptowidjojo, Marcio S. CarvalhoAbstract:Abstract Slide Coating is one of the pre-metered methods used for high precision single and multilayer Coatings. The thickness of each liquid layers is set by the flow rate and web speed only and it is independent of other process parameters. The uniformity of the deposited layer, however, is affected by the operating conditions. In the design of Coating processes, it is crucial to know the set of conditions at which the deposited layer is adequately uniform, i.e. to define the operability window of the process. We developed a theoretical model of Slide Coating flow by solving the full two-dimensional Navier–Stokes equations and used it to uncover the mechanisms of Coating bead breakdown at low vacuum, high vacuum, and low flow limits. With full understanding of the bead breakup processes, we then constructed a theoretical Coating window as a function of Coating thickness, web speed, and applied vacuum. A simple stability criterion was used to predict the onset of ribbing instability and deployed to add the onset of ribbing limit inside the Coating window.
Wonmok Lee - One of the best experts on this subject based on the ideXlab platform.
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flexible polymer opal films prepared by Slide Coating from alcoholic media
Macromolecular Research, 2017Co-Authors: Seulgi Kim, Hyunjung Lee, Young Gook Koh, Wonmok LeeAbstract:In this study, we investigated the fabrication of a colloidal photonic crystal film on flexible substrate, which can be used as a scaffold material for various photonic applications. A thin polyethylene terephthalate (PET) film was treated by oxygen plasma and then used as a flexible substrate. The surface characterizations revealed that the surface roughness increased, and that the treated PET film was rendered hydrophilic. The contact angles of the films with water/isopropyl alcohol (IPA) mixtures at five different weight ratios (25%, 40%, 50%, 60%, and 75% of IPA) prepared on both treated and non-treated PET films were measured. The results indicated that water/IPA wets on oxygen plasma-treated PET film. The colloidal dispersions were prepared in five different water/IPA mixtures, and Slide Coating was carried out on both PET films aided by hot air to promote opal formation. Serious dewetting of opal film was observed on the non-treated PET film, except that with a 75% IPA. However, the treated PET film enabled the formation of high-quality opal film, regardless of IPA content in colloidal dispersion. The optical properties and surface morphologies of opal films on flexible PET film were confirmed by reflectance spectra and scanning electron microscopy images of the respective films.
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hierarchical opal grating films prepared by Slide Coating of colloidal dispersions in binary liquid media
Journal of Colloid and Interface Science, 2015Co-Authors: Wonmok Lee, Seulgi Kim, Seulki Kim, Jinho Kim, Hyunjung LeeAbstract:Abstract There are active researches on well ordered opal films due to their possible applications to various photonic devices. A recently developed Slide Coating method is capable of rapid fabrication of large area opal films from aqueous colloidal dispersion. In the current study, the Slide Coating of polystyrene colloidal dispersions in water/i-propanol (IPA) binary media is investigated. Under high IPA content in a dispersing medium, resulting opal film showed a deterioration of long range order, as well as a decreased film thickness due to dilution effect. From the binary liquid, the dried opal films exhibited the unprecedented topological groove patterns with varying periodic distances as a function of alcohol contents in the media. The groove patterns were consisted of the hierarchical structures of the terraced opal layers with periodic thickness variations. The origin of the groove patterns was attributed to a shear-induced periodic instability of colloidal concentration within a thin channel during the Coating process which was directly converted to a groove patterns in a resulting opal film due to rapid evaporation of liquid. The groove periods of opal films were in the range of 50–500 μm, and the thickness differences between peak and valley of the groove were significantly large enough to be optically distinguishable, such that the coated films can be utilized as the optical grating film to disperse infra-red light. Utilizing a lowered hydrophilicity of water/IPA dispersant, an opal film could be successfully coated on a flexible Mylar film without significant dewetting problem.
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high speed fabrication of 3 dimensional colloidal photonic crystal films by Slide Coating of polymer microspheres with continuous feeding of colloidal suspension
Thin Solid Films, 2010Co-Authors: Seung Chul Gil, Seulgi Kim, Young Gon Seo, Jinsub Shin, Wonmok LeeAbstract:Abstract A simple, yet rapid fabrication method for large area colloidal crystal film is demonstrated. Aqueous colloidal dispersion sandwiched between a hydrophobic top cell and a hydrophilic bottom substrate formed a flat meniscus at the drying front, from which high quality colloidal crystal films were obtained within 20 min due to the strong capillary force exerted by accelerated water evaporation aided by hot air blowing. Continuous supply of the suspension enabled the fabrication of the colloidal crystal over large area (> 4 cm 2 ) without significant loss of colloids.