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Written by Dr. Paranjayee Mandal
PhD (Materials and Engineering Research Institute (MERI)) Sheffield Hallam University Google Scholar: https://scholar.google.co.uk/citations?user=rGXubiIAAAAJ&hl=en ResearchGate: https://www.researchgate.net/profile/Paranjayee-Mandal
Published: 0
Reviewed By Dr Alidad Amirfazli
Professor and York Research Chair in Surface Engineering and Instrumentation at York University, Canada. Google Scholar: https://scholar.google.com/citations?user=sl-cdFAAAAAJ&hl=en
Reviewed: 24
This is a practical guide to Surface Science for researchers working in the Automotive Industry.
In this all-new guide you’ll learn all about:
Let’s dive right in.
We analyze and improve the performance of automotive products by leveraging surface properties like surface tension and contact angles. These properties are crucial for understanding how coatings and treatments interact with vehicle surfaces, ultimately affecting the spread and adhesion of liquids on solids. Paints, sealants, and protective coatings rely heavily on these surface properties for their effectiveness and durability in the automotive industry. Automotive surface science merges precision engineering with material science to create products that not only protect and enhance vehicle surfaces but also maintain them. Striking the perfect balance between performance and appearance is paramount, ensuring that coatings can withstand environmental stressors, resist wear, and preserve the vehicle’s aesthetic appeal for years to come.
We use the important surface properties below to understand the behavior of Automotive products and improve their quality.
Young – Laplace Method
Polynomial Method
Dynamic Contact Angle
Ideally, when we place a drop on a solid surface, a unique angle exists between the liquid and the solid surface. We can calculate the value of this ideal contact angle (the so-called Young’s contact angle) using Young’s equation. In practice, due to surface geometry, roughness, heterogeneity, contamination, and deformation, the contact angle value on a surface is not necessarily unique but falls within a range. We call this range’s upper and lower limits the advancing contact angle and the receding contact angle, respectively. The values of advancing and receding contact angles for a solid surface are also very sensitive. They can be affected by many parameters, such as temperature, humidity, homogeneity, and minute contamination of the surface and liquid. For example, the advancing and receding contact angles of a surface can differ at different locations.
Practical surfaces and coatings naturally show contact angle hysteresis, indicating a range of equilibrium values. When we measure static contact angles, we get a single value within this range. Solely relying on static measurements poses problems, like poor repeatability and incomplete surface assessment regarding adhesion, cleanliness, roughness, and homogeneity.
In practical applications, we need to understand a surface’s liquid spreading ease (advancing angle) and removal ease (receding angle), such as in painting and cleaning. Measuring advancing and receding angles offers a holistic view of liquid-solid interaction, unlike static measurements, which yield an arbitrary value within the range.
This insight is crucial for real-world surfaces with variations, roughness, and dynamics, aiding industries like cosmetics, materials science, and biotechnology in designing effective surfaces and optimizing processes.
Learn how Contact Angle measurement is done on our Tensiometer
For a more complete understanding of Contact Angle measurement, read our Contact Angle measurement: The Definitive Guide
This property measures the force that acts on the surface of a liquid, aiming to minimize its surface area.
Dynamic Surface Tension
Dynamic surface tension differs from static surface tension, which refers to the surface energy per unit area (or force acting per unit length along the edge of a liquid surface).
Static surface tension characterizes the equilibrium state of the liquid interface, while dynamic surface tension accounts for the kinetics of changes at the interface. These changes could involve the presence of surfactants, additives, or variations in temperature, pressure, and composition at the interface.
Dynamic surface tension is essential for processes that involve rapid changes at the liquid-gas or liquid-liquid interface, such as droplet and bubble formation or coalescence (change of surface area), behavior of foams, and drying of paints (change of composition, e.g., evaporation of solvent). We measure it by analyzing the shape of a hanging droplet over time.
Dynamic surface tension applies to various industries, including cosmetics, coatings, pharmaceuticals, paint, food and beverage, and industrial processes, where understanding and controlling the behavior of liquid interfaces is essential for product quality and process efficiency.
Learn how Surface Tension measurement is done on our Tensiometer
For a more complete understanding of Surface Energy measurement, read our Surface Tension measurement: The Definitive Guide
Learn how Surface Energy measurement is done on our Tensiometer
For a more complete understanding of Surface Energy measurement, read our Surface Energy measurement: The Definitive Guide
The sliding angle measures the angle at which a liquid film slides over a solid surface. It is commonly employed to assess the slip resistance of a surface.
Learn how Sliding Angle measurement is done on our Tensiometer
For a more complete understanding of Sliding Angle measurement, read our Sliding Angle Measurement: The Definitive Guide
Within the Automotive industry, several case studies exemplify the advantages of conducting surface property measurements.
We applied four different paints (A, B, C, and D) to curved metal surfaces like car hoods and doors to identify the most water-repellent option. We used contact angle as the key measure, with a larger angle indicating better water repellency. Paint A completely absorbed water droplets, while Paint B formed a 36-degree contact angle. Paints C and D achieved even better results, with contact angles of 42 and 58 degrees, respectively. These measurements represent the average of 8 and 10 readings for paints A and B, and C and D, respectively. Based on these results, Paint D emerges as the most suitable candidate for water resistance, clearly demonstrated by its superior contact angle. Conversely, Paint A proves entirely unsuitable, allowing water to spread and potentially be absorbed due to its minimal contact angle.
The automotive industry prioritizes maintaining clear visibility for drivers during rain to ensure safety. Traditional windshields often struggle with water build-up, compromising visibility and putting drivers at risk. To address this, the industry has developed a unique solution: applying a hydrophobic coating with a low sliding angle to automotive windshields. This low angle allows rainwater to easily slide off the surface, significantly reducing water build-up and dramatically improving driver visibility and safety in rainy conditions.
If you are interested in implementing these or any other applications, please contact us.
In an industry where precision reigns supreme, where do Automotive manufacturers turn to ensure their products can survive scrutiny? The answer lies in standards and guidelines: the compass that guides cosmetics manufacturers through the complex maze of quality and performance.
This test method describes the standard practice for surface wettability of coatings, substrates, and pigments by advancing contact angle measurement. This procedure covers the advancing CA measurement when a liquid drop is applied to a coated surface, substrate, or preformed disk of pigment.
This standard test method describes how the surface tension of solid coatings, substrates, and pigments using contact angles (CA) can be measured. In this procedure, CA of two liquids (polar and nonpolar) of known surface tension on a substrate, pigment (in the form of a disk), or cured or air-dried coating are measured to calculate the surface properties (surface tension and its dispersion and polar components) of the solid.
This ISO 19403 series describes optical test methods for (i) contact angles measurement, (ii and iii) determination of free surface energy of a solid surface and surface tension of liquids, including the polar and dispersive fractions, and (iv) checking of obtained results with reference materials. This series applies to characterizing the substrates, coatings, and coating materials, but is restricted to non-Newtonian rheology liquids.
This standard describes a method of measuring the contact angles (CA) of water droplets on any polymer film surfaces (when showing no chemical affinity for water) and subsequently determining the wetting tension of the film. This standard uses three different apparatus for CA measurement, such as goniometer, droplet image projection, and computer-based system.
We hope this guide showed you how to apply surface science in cosmetics industry.
Now we’d like to turn it over to you:
Droplet Lab was founded in 2016 by Dr. Alidad Amirfazli, faculty member at York University, and two of his researchers, Dr. Huanchen Chen and Dr. Jesus L. Muros-Cobos.
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