Wettability of Metal Surfaces Affected by Paint Layer Covering.

Stanislaw Pogorzelski,Maciej Grzegorczyk,Katarzyna Boniewicz-Szmyt,Pawel Rochowski

doi:10.3390/ma15051830

Stanislaw Pogorzelski, Maciej Grzegorczyk + Show 2 more

Open Access

https://doi.org/10.3390/ma15051830

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Journal: Materials	Publication Date: Feb 28, 2022
Citations: 8	License type: CC BY 4.0

Affiliation: University of Gdańsk, Gdynia Maritime University

Abstract

The aim of the work was to quantify the surface wettability of metallic (Fe, Al, Cu, brass) surfaces covered with sprayed paints. Wettability was determined using the contact angle hysteresis approach, where dynamic contact angles (advancing ΘA and receding ΘR) were identified with the inclined plate method. The equilibrium, ΘY, contact angle hysteresis, CAH = ΘA − ΘR, film pressure, Π, surface free energy, γSV, works of adhesion, WA, and spreading, WS, were considered. Hydrophobic water/solid interactions were exhibited for the treated surfaces with the dispersive term contribution to γSV equal to (0.66–0.69). The registered 3D surface roughness profiles allowed the surface roughness and surface heterogeneity effect on wettability to be discussed. The clean metallic surfaces turned out to be of a hydrophilic nature (ΘY < 90°) with high γSV, heterogeneous, and rough with a large CAH. The surface covering demonstrated the parameters’ evolution, ΘA↑, ΘR↑, γSV↓, WA↓, and WS↓, corresponding to the surface hydrophobization and exhibiting base substratum-specific signatures. The dimensionless roughness fluctuation coefficient, η, was linearly correlated to CAH. The CAH methodology based on the three measurable quantities, ΘA, ΘR, and liquid surface tension, γLV, can be a useful tool in surface-mediated process studies, such as lubrication, liquid coating, and thermoflow.

Highlights

Surface preparation is an essential step to obtain specific substrates to be applied in several processes, such as corrosive layer deposition, lubrication, spreading rheology, liquid thermoflow control, etc
A set of the surface wettability energetics parameters revealed the general trend of their variability as follows: ΘY↑, ΘA↑, ΘR↑, CAH↑, γSV↓, WA↓, and WS less negative, characteristic for the surface hydrophobization
A spatial evolution of the data points distribution in the space of CAH versus WS made it possible to distinguish between the processes simultaneously taking place, i.e., micro-roughness smoothing, chemical paint components distribution and mixing at the outermost surface; they turned out to be base substratum specific

Summary

Introduction

Surface preparation is an essential step to obtain specific substrates to be applied in several processes, such as corrosive layer deposition, lubrication, spreading rheology, liquid thermoflow control, etc. Solid material wettability is a fundamental property which reveals specific information on the surface chemical structure, component miscibility, and spatial heterogeneity, apart from the surface roughness morphology which is likely to be strongly correlated to the treatment process conditions (relative humidity, temperature, vibrations, process time scale, etc.). Wetting measurements based on the contact angle (CA) determination are among the most sensitive and commonly realized surface-sensing techniques with an extremely low analysis depth of the order of nm [1]. The determination of solid surface free energy, γSV, and its components is realized by means of several theoretical approaches based on the so-called Young equilibrium contact angle, ΘY [2].

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