scholarly journals Drying of a Colloidal Suspension Deposited on a Substrate: Experimental and Numerical Studies

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 829
Author(s):  
Nathalie Olivi-Tran ◽  
Laurent Bonnet ◽  
Pascal Etienne
Keyword(s):  
Brownian Motion ◽  
Glass Substrate ◽  
Open Channel ◽  
Colloidal Suspension ◽  
Van Der Waals ◽  
Optical Microscope ◽  
Diffuse Layer ◽  
Viscous Drag ◽  
Light Bulb ◽  
Optical Pressure

We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical microscope, the light bulb of which acted as an energy source to evaporate the suspension. Moreover, the light bulb of the microscope provided optical pressure due to light. We observed that the colloidal particles were trapped on the rough areas of the substrate and not in the open channel at the end of the drying process. In order to understand the experimental results, we modeled numerically the drying of the suspension using a Molecular Dynamics program. The forces imposed on the substrate by the particles are their weight, the optical pressure due to the light bulb of the optical microscope, the attractive Van der Waals force and the repulsive diffuse layer force. The forces acting between two particles are the attractive Van der Waals forces, the repulsive diffuse layer force and the capillary force. The Gaussian random force (linked to Brownian motion) and the particle liquid viscous drag force (also linked to Brownian motion) are horizontal and applied on one particle. The relation between the normal forces N (forces acting by the particles on the substrate) and the horizontal forces F is Amontons' third law of friction F ≤ μk N; in rough areas of the substrate, μk is larger than in smooth areas. This explains that particles are trapped in the areas with high roughness.

scholarly journals Imaging of Interlayer Coupling in van der Waals Heterostructures Using a Bright-Field Optical Microscope

Nano Letters ◽  
2017 ◽  
Vol 17 (9) ◽  
pp. 5342-5349 ◽  
Author(s):  
Evgeny M. Alexeev ◽  
Alessandro Catanzaro ◽  
Oleksandr V. Skrypka ◽  
Pramoda K. Nayak ◽  
Seongjoon Ahn ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Interlayer Coupling ◽  
Optical Microscope ◽  
Bright Field ◽  
Van Der Waals Heterostructures

Monte Carlo simulation of Brownian motion with viscous drag

1978 ◽  
Vol 46 (5) ◽  
pp. 543-545 ◽  
Author(s):  
L. Gunther ◽  
D. L. Weaver
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Brownian Motion ◽  
Viscous Drag

scholarly journals Deposition of Photo-Catalytic Tio2 Film by Low Power Atmospheric Suspension Plasma Spray Using Ar/N2 Working Gas

2018 ◽  
Author(s):  
Sagr Hsain ◽  
Yasutaka Ando
Keyword(s):  
Low Power ◽  
Thermal Spray ◽  
Plasma Spray ◽  
Low Cost ◽  
Colloidal Suspension ◽  
Deposition Process ◽  
Optical Microscope ◽  
Film Deposition ◽  
Suspension Plasma Spray ◽  
Titanium Hydroxide

As a photo-catalytic titanium oxide film deposition process, thermal spray is hoped to be utilized practically on the condition that it is relatively easy to deposit anatase rich films. However, because of its high equipment and feedstock powder costs, it is very difficult to introduce thermal spray equipment into small companies. In this study, to develop a low cost thermal spray system, low power atmospheric suspension plasma spray equipment with titanium hydroxide suspension created by hydrolysis of titanium tetra iso butoxide using Ar, N2 as working gases. For avoiding sedimentation of the hydroxide particles in the suspension, mechanical milling of the suspension was conducted to create colloidal suspension before using it as feedstock. Moreover, an Ultrasonic wave container was used to keep the suspension particles moving while the spray process was conducted. After the film deposition, with As for the coating, anatase rich TiO2 film could be obtained. For characterization of the film, microstructure observation by optical microscope and X-ray diffraction was carried out. Consequently, by creation of colloidal suspension, deposition could be conducted without sedimentation of the hydroxide particle in the suspension during operation. Besides, it was proved the film had enough photo-catalytic property to decolor methylene-blue droplet

Water Assisted Growth of Two-Dimensional MoS2/MoSe2 Vertical Heterostructures on Molten Glass

Nanoscale ◽  
2022 ◽  
Author(s):  
Qian Cai ◽  
Qiankun Ju ◽  
Wenting Hong ◽  
Chuanyong Jian ◽  
Taikun Wang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Glass Substrate ◽  
Molten Glass ◽  
Large Scale ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
Controlled Growth ◽  
Two Dimensional ◽  
Van Der Waals Heterostructures

Herein, we demonstrate a chemical vapor deposition route to controlled growth of large scale MoS2/MoSe2 vertical van der Waals heterostructures on molten glass substrate using water as the oxidizing chemical...

Computer Simulation of Aerosol Motion

1994 ◽  
Author(s):  
Bruce S. MacGibbon ◽  
Ahmed A. Busnaina
Keyword(s):  
Computer Simulation ◽  
Brownian Motion ◽  
Equation Of Motion ◽  
Viscous Drag ◽  
Lagrangian Equation ◽  
Particle Trajectories ◽  
Aerosol Dynamics ◽  
General Review

Abstract This paper is a general review of aerosol dynamics. A Lagrangian equation of motion is presented that incorporates forces that may act on a particle. Included are the influences of viscous drag, gravity, lift, brownian motion, thermophoresis, electrophoresis, photophoresis, and turbulence. Using the equation of motion, particle trajectories can be numerically simulated for given fluid conditions.

The Synthesis and Phase Behavior of a Novel Discoticnematic Triphenylene Mesogen and its Application to an Optically Anisotropic Film

2008 ◽  
Vol 373-374 ◽  
pp. 678-681 ◽  
Author(s):  
Chun Xiu Zhang ◽  
Zhi Qun He ◽  
Jia Ling Pu ◽  
Jun Jie Wang ◽  
Yong Sheng Wang ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Thermal Behavior ◽  
Phase Behavior ◽  
Differential Scanning Calorimeter ◽  
Glass Substrate ◽  
Nematic Phase ◽  
Polyimide Film ◽  
Optical Microscope ◽  
X Ray Diffraction ◽  
X Ray

A novel discotic triphenylene derivative bearing one triphenylene discogen as core and three cyano-biphenyl moieties was synthesized and its thermal behavior was studied using polarizing optical microscope, differential scanning calorimeter and X-ray diffraction. It was found that this molecule containing [decylene?] spacers showed nematic phase. After being mixed with methyl methacrylate (MMA), the discogen showed nematic phase at the mesophase temperature range (64~85 °C) and oriented spontaneously in the mixture after annealing for 2 hours in the mixture. The orientation can be stabilized by the polymerization of MMA. The orientation can be fixed by the polymerization of MMA. It was treated directly on glass substrate, which surface did not treat by polyimide film and confirmed the orientation was proved by X-ray diffraction. This offers If the alignment of the discotic molecules can be freely controlled and fixed, a useful mean to produce new area of optically anisotropic film will be produced with this material.

Gravity-induced coalescence of drops at arbitrary Péclet numbers

1994 ◽  
Vol 280 ◽  
pp. 119-148 ◽  
Author(s):  
Alexander Z. Zinchenko ◽  
Robert H. Davis
Keyword(s):  
Distribution Function ◽  
Brownian Motion ◽  
Peclet Number ◽  
Pair Distribution Function ◽  
Van Der Waals ◽  
Numerical Results ◽  
Collision Efficiency ◽  
Péclet Number ◽  
Wide Range ◽  
Medium Viscosity

The collision efficiency in a dilute suspension of sedimenting drops is considered, with allowance for particle Brownian motion and van der Waals attractive force. The drops are assumed to be of the same density, but they differ in size. Drop deformation and fluid inertia are neglected. Owing to small particle volume fraction, the analysis is restricted to binary interactions and includes the solution of the full quasi-steady Fokker—Planck equation for the pair-distribution function. Unlike previous studies on drop or solid particle collisions, a numerical solution is presented for arbitrary Péclet numbers, Pe, thus covering the whole range of particle size in typical hydrosols. Our technique is mainly based on an analytical continuation into the plane of complex Péclet number and a special conformal mapping, to represent the solution as a convergent power series for all real Péclet numbers. This efficient algorithm is shown to apply to a variety of convection—diffusion problems. The pair-distribution function is expanded into Legendre polynomials, and a finite-difference scheme with respect to particle separation is used. Two-drop mobility functions for hydrodynamic interactions are provided from exact bispherical coordinate solutions and near-field asymptotics. The collision efficiency is calculated for wide ranges of the size ratio, the drop-to-medium viscosity ratio, and the Péclet number, both with and without interdroplet forces. Solid spheres are considered as a limiting case; attractive van der Waals forces are required for non-zero collision rates in this case. For Pe [Gt ] 1, the correction to the asymptotic limit Pe → ∞ is O(Pe−1/2). For Pe [Lt ] 1, the first two terms in an asymptotic expansion for the collision efficiency are C/Pe + ½C2, where the constant C is determined from the Brownian solution in the limit Pe → 0. The numerical results are in excellent agreement with these limits. For intermediate Pe, the numerical results show that Brownian motion is important for Pe ≤ O(102). For Pe = 10, the trajectory analysis for Pe → ∞ may underestimate the collision rate by a factor of two. A simpler, approximate solution based on neglecting the transversal diffusion is also considered and compared to the exact solution. The agreement is within 2–3% for all conditions investigated. The effect of van der Waals attractions on the collision efficiency is studied for a wide range of droplet sizes. Except for very high drop-to-medium viscosity ratios, the effect is relatively small, especially when electromagnetic retardation is accounted for.

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