The normal force evolution of the substrate during the withdrawal process

The evolution of normal force on the smooth plate immersed in Newtonian and yield stress fluids was investigated during the dip coating. The influences of withdrawal velocity, liquid rheological property, and plate roughness were elaborated. For all fluids, the variation of force versus the withdraw...

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Bibliographic Details
Published in:Polymer engineering and science 2022-10, Vol.62 (10), p.3241-3253
Main Authors: Zhang, Heng‐Kuan, Yin, Ya‐Ran, Pan, Xu‐Qi, Zhang, Xian‐Ming, Chen, Wen‐Xing, Hu, Guo‐Hua
Format: Article
Language:English
Subjects:
Analysis
Coating processes
coatings
Engineering Sciences
Evolution
Immersion coating
Immersion plating
Methods
Rheological properties
shear
Stability analysis
Substrates
Surface tension
tension
Viscosity
Yield stress
yielding
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Summary:The evolution of normal force on the smooth plate immersed in Newtonian and yield stress fluids was investigated during the dip coating. The influences of withdrawal velocity, liquid rheological property, and plate roughness were elaborated. For all fluids, the variation of force versus the withdrawing height was divided into four stages. Importantly, the control forces for coating in each stage were determined, which are in turn viscous force‐capillary, viscous force‐gravity, capillary‐viscous force, and gravity. The critical value of normal force controlled from capillary to viscous effect during drainage was adopted to calculate the surface tension. The possibility of measuring the surface tension was verified under the negligible interference of viscous effect and film instability through a detailed analysis on the evolution of force in a series of tests. Accordingly, the applicable conditions with the low withdrawal speed, high viscosity, and rough surface were finally achieved. This work can provide a theoretical basis for the film‐formation mechanism and surface tension measurement in dip coating. The evolution of normal force on the substrate and the surface tension measurement during withdrawal from Newtonian and yield stress fluids.
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.26099