Organic molecules on a metal surface … a machinist’s best friend

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WEST LAFAYETTE, Ind. – How to improve the cutting of “gummy” metals? Innovators at Purdue University have found an answer – and their findings can help manufacture products and reduce component failures.

Researchers have previously shown that applying a permanent marker or Sharpie, glue or adhesive film makes it easier to cut metals such as aluminum, stainless steels, nickel, copper and tantalum. for industrial applications. Marking the metal surface to be machined with ink or adhesive dramatically reduced the cutting force, leaving a clean cut in seconds. Now they have found out how these films produce the effect.

“We’ve found that you only need one thick molecule of organic film markers or glue for it to work,” said Srinivasan Chandrasekar, professor of industrial engineering at Purdue. “This ultra-thin film results in smoother, cleaner and faster cuts than current machining processes. It also reduces cutting forces and energy, and improves manufacturing results in industries such as biomedical, energy, defense and aerospace.

Purdue University engineers Anirudh Udupa (seated) and Srinivasan Chandrasekar (standing) analyze metal surfaces to look for deformations created during cutting to determine how the applied materials affect the quality of the cut. (Image from Purdue University / Erin Easterling)

The research is published in Science Advances. The study involves a collaboration between researchers at Purdue, the University of Osaka (Japan) and the Indian Institute of Science (India). The research is supported by the National Science Foundation and the US Department of Energy.

If a significant improvement can be made in the machinability of gummy metals or alloys – that is, how well they cut, puncture or grind – then it is possible to reduce the cost of the products, improve their performance. or enable new and improved product designs.

Researchers have found, using organic monolayer films created by molecular self-assembly, that the length of the molecular chain and its adsorption to the metal surface are essential to achieve these improvements. By using the “good” organic molecules, the metal is locally weakened, which improves machining.

“Through our discovery, we are also learning more about how environmental factors influence metal failure,” said Anirudh Udupa, lead author of the study and a researcher at the School of Industrial Engineering at Purdue. “As we decipher how organic molecular films improve the machinability of these metals, the better our understanding of common metal failures, such as stress corrosion cracking, hydrogen embrittlement and embrittlement of liquid metals. “

Purdue innovators worked with the Purdue Research Foundation Office of Technology Commercialization to patent this technology.

Researchers are looking for partners to continue to develop their technology. For more information on licensing and other opportunities, contact OTC at [email protected] and mention the track code 2019-CHAN-68634.

About the Purdue Research Foundation’s Office of Technology Commercialization

The Purdue Research Foundation Office of Technology Commercialization operates one of the most comprehensive technology transfer programs among leading research universities in the United States. intellectual property. The office recently moved into the Convergence Center for Innovation and Collaboration in the Discovery Park district, adjacent to the Purdue campus. In FY2020, the office reported 148 agreements finalized with 225 technologies signed, 408 disclosures received, and 180 U.S. patents issued. The office is managed by the Purdue Research Foundation, which received the 2019 Innovation and Economic Prosperity Universities Award for Place from the Association of Public and Land-grant Universities. In 2020, the IPWatchdog Institute ranked Purdue third nationally for creating startups and in the top 20 for patents. The Purdue Research Foundation is a private, not-for-profit foundation created to advance the mission of Purdue University. Contact [email protected] for more information.

About Purdue University

Purdue University is a leading public research institution that develops practical solutions to today’s most difficult challenges. Ranked # 5 most innovative universities in the United States by US News & World Report, Purdue delivers world-changing research and extraordinary discoveries. Engaged in hands-on, online learning in the real world, Purdue provides transformative education for everyone. Committed to affordability and accessibility, Purdue has frozen tuition and most fees at 2012-2013 levels, allowing more students than ever to graduate debt-free. Find out how Purdue never stops in the persistent pursuit of the next giant leap at purdue.edu.

Writer: Chris Adam, [email protected]

Sources:
Srinivasan Chandrasekar, 765-494-3623, [email protected]

Anirudh Udupa, [email protected]


ABSTRACT

Organic monolayers disrupt plastic flow in metals

Tatsuya Sugihara, Anirudh Udupa, Koushik Viswanathan, Jason M Davis

and Srinivasan Chandrasekar

Adsorbed films often influence the mechanical behavior of surfaces, leading to well-known mechanochemical phenomena such as liquid metal embrittlement and environmentally assisted cracking. Here, we demonstrate a previously unidentified mechanochemical phenomenon in which adsorbed long-chain organic monolayers disrupt high-stress plastic deformation in metals. Using high speed in situ Imaging and post-facto analysis, we show that the monolayers induce a ductile to brittle transition. The sinuous flow, characteristic of ductile metals, gives way to quasi-periodic failure, typical of brittle materials, with an 85% reduction in deformation forces. By independently varying the surface energy and molecular chain length via molecular self-assembly, we argue that this “embrittlement” is due to adsorbate-induced surface stress, as opposed to reduction of l surface energy. Our observations, supported by modeling and molecular simulations, could provide a basis for explaining various mechanochemical phenomena in solids. Additionally, the results have implications for manufacturing processes such as machining and grinding, and wear.


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