Slot coating flows of non‐colloidal particle suspensions

Abstract

Slot coating is used in the manufacturing of functional films, which rely on specific particle microstructure to achieve the desired performance. Final structure on the coated film is strongly dependent on the suspension flow during the deposition of the coating liquid and on the subsequent drying process. Fundamental understanding on how particles are distributed in the coated layer enables optimization of the process and quality of the produced films. The complex coating flow leads to shear‐induced particle migration and non‐uniform particle distribution. We study slot coating flow of non‐colloidal suspensions by solving the mass and momentum conservation equations coupled with a particle transport equation using the Galerkin/Finite element method. The results show that particle distribution in the coating bead and in the coated layer is non‐uniform and is strongly dependent on the imposed flow rate (wet thickness). © 2016 American Institute of Chemical Engineers AIChE J, 63: 1122–1131, 2017

Preparation, Performance and Challenges of Catalyst Layer for Proton Exchange Membrane Fuel Cell

“…(2) Slot die coating [178,179] The slot coating machine is a widely used piece of coating equipment in CL preparation. The precision injection pump is used to control the feeding speed (feeding quantity), and the coating thickness is controlled by the height between the mold and the substrate, the gap size of the mold head, the substrate moving speed and other factors.…”

Computational study of planar extrudate swell flows with a viscous liquid–gas interface

“…The method has been successfully used to study different free surface flows of Newtonian liquids, 9,17-21 viscoelastic polymer solutions, [22][23][24][25][26] and particle suspensions. [27][28][29][30][31] We present a brief review of the overall numerical scheme in this section. The interested reader can find more details elsewhere (e.g., see Pasquali 32 and the references therein).…”

“…The computational method used in this work is based on a mixed finite element formulation for free surface flows. The method has been successfully used to study different free surface flows of Newtonian liquids, 9,17–21 viscoelastic polymer solutions, 22–26 and particle suspensions 27–31 . We present a brief review of the overall numerical scheme in this section.…”

Shear-induced particle migration in the flow of particle suspensions through a sudden plane expansion

“…In addition to that, the singularity of the particle transport equation as the local shear rate approaches zero was treated using the non-local contribution to the shear stress [29][30][31]. This version of the DEVSS-TG formulation together with finite element basis functions has been successfully used in recent studies of particle migration in complex flows of particle suspensions and more details can be found elsewhere [33][34][35][36].…”

“…Another problem is related to its numerical implementation, since the model becomes singular as the local shear rate approaches zero, as occurs near the symmetry plane of pressure-driven flows through tubes and channels [29,30]. However, because of its relative simplicity, good accuracy and low computational cost, the diffusive flux model has been extensively used to study particle migration in many different problems involving complex flows, such as flows through two-and three-dimensional bifurcations [31,32], free-surface flows [33,34], and flows of suspensions with non-spherical particles [35,36]. Alternative approaches have also considered variations of the diffusive flux model to study particle migration in suspensions with a non-Newtonian continuous phase [37,38].…”