Tag Archives: surface contaminants
BTG Labs will be attending the SAE (Society of Automotive Engineers) AMS Aerospace Organization Coatings Committee (AMS G-8)’s annual meeting May 3-5. Dr. Giles Dillingham and Lucas Dillingham will present on “An Integrated Approach to Quantification of Contaminant Effects on Surface Sensitive Processes.” The presentation is based on a collaboration with Lockheed Martin Skunkworks under DARPA support about a new approach at studying surface contaminants. This new approach proposes studying contaminants according to their chemical structure rather than the conventional way which studies the effects of complex contaminant mixtures without identifying and studying individual contaminants. G-8, a branch of SAE, studies adhesive bonding of composites and composes the handbook for bonding composites in aircraft, as well as the publication of the CMH-17 Handbook. SAE strives to standardize language relevant to data generation, testing, and reporting of composites. Below is the abstract for Dr. Dillingham’s presentation.
An Integrated Approach to Quantification of Contaminant Effects on Surface Sensitive Processes ~ Lucas Dillingham, Giles Dillingham / BTG Labs
The detrimental effects of a contaminant are determined by i) the amount of the contaminant in the environment, ii) the affinity of the contaminant for the critical surface, and iii) the compatibility (i.e. solubility) of the contaminant in the adhesive or coating. The most common approach for evaluating contaminant effects has been to evaluate the effect of a complex blend of multiple contaminants. Because this approach provides no information as to what makes a given contaminant detrimental, it limits our ability to predict the effect of an untested contaminant. Developing an understanding of the relationship between contaminant structure and effect can lead to more intelligent design of surface preparation processes, more robust adhesive and coating formulations, and more reliable manufacturing processes.
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BTG Lab’s Collaborations
This paper, written as part of an ongoing collaboration between BTG, Southwest Research Institute, and Lockheed Martin Skunkworks. Funded by the Defense Advanced Research Projects Agency (DARPA), the collaborators examine and develop techniques for engineering a certifiable bonded method for aircraft manufacturing. The use of composites is increasingly employed in aircraft manufacturing to replace titanum and aluminum. However, composites weaken by the use of fasteners such as bolts and rivets. This is where the implementation of adhesives comes in. The understanding of surfaces requires knowledge on how an adhesive will stick to the surface and the presence of contaminants.
A New Approach
Studying the effects and habits of contaminants can be an essential step in any bonding or adhesion process as a contaminant can significantly influence the success of an adhesive or bond. All surfaces contaminate upon exposure, making them inevitable to any process. Thus, understanding the relationship between a contaminant structure and the effect it has on a bond will help develop more productive monitoring procedures for preparation processes, stronger adhesives and coating formulations, and more reliable construction.
The current method to evaluate the effect of contaminants on a surface entails examining a complex cocktail of them. However, not all contaminants in the blend might exist in a given manufacturing environment. The cocktail method fails to inform us of the effects an individual contaminant will have on a surface.
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Handheld Solution for Verifying Surface Cleanliness
The Surface Analyst™ is an innovative handheld solution for use in the lab and on the factory floor. It reduces waste, rework, and recalls when poorly prepared substrate surfaces lead to bonding, coating, sealing, painting, or printing failure.
Using contact angle measurement, the Surface Analyst measures the cleanliness level of surfaces and determines preparedness for adhesion. Developed and manufactured by BTG Labs, it is a fast, easy, accurate, and nondestructive instrument for manufacturers with critical surface requirements. The Surface Analyst replaces legacy methods such as dyne and water break tests.
Measuring Contact Angle to Determine Surface Cleanliness
The Surface Analyst deposits a highly purified drop of water on the surface. In two seconds, it measures the contact angle and in turn, determines the cleanliness level of a substrate.
When a surface is clean, it emits high energy, and water–as a high energy molecule–spreads out on the surface, in attraction to other high energy molecules (Figure 1). A contaminated surface emits low energy and will cause water to bead up in attraction to itself rather than the low energy surface molecules (Figure 2).
By knowing the volume and area of a drop of water, the contact angle of the water against a given surface can be determined. The larger the contact angle, the more the water beads up on the surface – and therefore the lower the energy level of the surface.
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