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December 2007 |
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| History of the ramé-hart Goniometer | ||||
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For over four decades the classic ramé-hart
Model A100 and later 100-00 was referred to as the NRL goniometer. And
rightfully so: it was the brainchild of Dr. William A Zisman of the
Naval Research Lab's (NRL) Chemistry Division where it was born in the
early 1960's. Dr. Zisman was a man of incredible genius and a pioneer in
surface chemistry. He was by training a physicist but became enthralled
in the exciting developments in the arena of surface science --
following in the footsteps of Langmuir, Rideal, and Harkins. His passion
was so great that in 1938 he actually quit his job in Washington for a
year and personally financed a year of study in the laboratory of the
late Dr. Goranson at the Carnegie Geophysical Laboratory. The following
year he successfully lobbied for a research program in surface chemistry
and was hired to steer that program at the Naval Research Lab, later
heading up the entire Chemistry Division.
While at NRL, Dr. Zisman developed the vibrating condenser method of measuring contact potential, a method that has been widely used since then. In fact, he did his master's thesis on this topic at MIT. He also did significant work on oils and during the war he made many important observations that led to the development of synthetic lubricants and additives. Perhaps no one of his era made greater contributions to the vast collection of excellent data on contact angle, wettability, surface tension, and adhesion. He was the author of over 100 publications and his name was on nearly two dozen patents, mostly for lubricants and protective treatments for surfaces. He also authored Zisman's Plot method which is incorporated in our DROPimage software. In 1963 he received the Kendall Award from the American Chemical Society for his vast contributions to surface science.
Here at ramé-hart, our particular appreciation for Dr. Zisman's contributions are somewhat biased and focused on his design of the ramé-hart NRL goniometer. Although the instrument has been redesigned several times over the years, there are a number of components that are still in use today. We continue to use the same standard 3" wide by 2" deep leveling specimen stage from the original design although the leveling hardware is now much easier to negotiate. The 3-axis stage of our Models 300 and 500 are essentially the same as the original model A100 stage attesting to the time-proven design of Dr. Zisman. The optical bench was converted from the original U-rail design in favor of our current ceramic-coated rails and Frelon bearings. Our new design wears better and longer and supports a more flexible load. The backlighting system has also changed. The original incandescent bulb mounted in a housing with an aperture has been replaced with far superior LCD and halogen technology. Our current illuminator is powered via a fiber optic bundle connected to an independent light source. Our Model 120-F0 uses our newer LCD technology.
The optical subsystem has changed the most. The original NRL goniometer used a microscope for visual measurement of the drop dimension and contact angle. All of our goniometers now employ a digital camera and our DROPimage software to capture and analyze the drop shape and profile as well as a measure the drop dimensions, contact angles, surface energy, surface tension, and other important values. If Dr. Zisman were around today, he
would be pleased with what his creation has become. There are over 3000
ramé-hart goniometers in use throughout the world. No other manufacturer
of contact angle instruments has a wider world-wide market presence or
richer history in measuring contact angle, surface energy, and surface
tension. |
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