Tag Archives: Ballistic Deposition
This week, BTG Labs will attend the CMH-17 PMC Coordination Meeting in conjunction with ASTM D-30 in Salt Lake City, Utah. The purpose of this gathering is to present and collaborate on the latest in composite advances and standards and contribute to document updates.
CMH-17, the Composite Materials Handbook, is the go to reference and guide for aerospace manufacturers who adhesively bond composite parts. It features standard, vetted composite technologies as well as standardization for data collection and analysis of composite processes. BTG Labs maintains a strong connection with CMH-17 by presenting at working group meetings and contributing to content.
This year, BTG Labs’ Chief Scientist Dr. Giles Dillingham and Research and Development Engineer Tim Barry will attend the March meeting to collaborate and present.
Dr. Dillingham and Barry will present BTG Labs’ work to a joint meeting of ASTM committees D30 and D14.80.01 on adhesives and composites. This presentation intends to create a new standard based on BTG Labs’ Surface Analyst™, a handheld instrument which measures water contact angle in 2 seconds to ensure bonding. The proposed standard especially focuses on the instrument’s unique abilities to deposit water drops via patented Ballistic Deposition technology and image drops from above to determine the contact angle.
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Most Frequently Asked Questions
1. Does surface roughness affect the measurement? Can you measure on curved parts? Because the Surface Analyst uses patented Ballistic Deposition to deposit liquid drops, the user can easily take measurements on surfaces with varied shapes, orientation, and texture. While Ballistic Deposition minimizes roughness effects, if the roughness varies greatly from point to point, there can be a small effect on the contact angle.
2. Does measuring vertically impact the measurement? No. Because the Surface Analyst uses very small liquid drops, surface tension forces on the drop are much greater than gravitational forces. Therefore, orientation of the surface does not effect measurement: vertical, inverted, inclined surfaces all return the same value of contact angle.
3. How does it compare to a benchtop system? Unlike a benchtop goniometer, the Surface Analyst is portable and handheld, and removes subjectivity on the part of the operator in taking a measurement. It is designed to work on the surfaces of manufactured parts: injection molded, machined, sanded, blasted, painted, etc. where a benchtop goniometer is limited when it comes to measurements on parts with contours, shapes, and surface roughness. The precision of the contact angle calculation is equal to or better than a benchtop system.
4. What is the output of the system? What is it actually measuring? The Surface Analyst measures the contact angle of water, which is primarily sensitive to the polar component of the total surface energy. With a simple calibration curve, the water contact angle can be precisely correlated to the total surface energy. The surface energy of a material directly relates to cleanliness and to the potential to form a strong bond with an adhesive or coating.
5. What is the repeatability? The Surface Analyst has a repeatability better than 1° on well-prepared surfaces.
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Fluid Deposition Style of Contact Angle Measurements
Measuring the contact angle of a fluid on a surface provides an accurate reading of surface energy. However, methods of depositing the droplet and measuring the contact angle vary. With this sensitive process, every detail and particularity effects the measurement.
Common surface measurement instruments, such as goniometers, use an automated syringe needle to deposit a single drop of fluid. However, the manner in which the drop of fluid is deposited greatly impacts the contact angle and entails precise control. Furthermore, the composition of fluid used effects the measurement and potentially the surface.
Alternative fluids can be dangerous to the user and contamination to the material. This often requires the use of a coupon, or sample rather than a measurement on the actual surface of the material in question. Furthermore, a single drop does not have the ability to measure on diverse surfaces.
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