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February 9th, 2009

Nanocoated pump seal wins ‘Oscar’ of invention

Published on February 9th, 2009 | By: pwray@ceramics.org
A continuous coating

A thin nanocoating of diamond fragments makes UNCD seals strong, smooth and energy efficient.

Dubbed the “Oscars of Innovation” by the Chicago Tribune, the R&D 100 Awards, presented annually by R&D magazine, are a badge of distinction that identifies a product as one of the most creative and noteworthy inventions of the year. Researchers at Argonne National Lab, aided by two Illinois firms, have captured one of these 2008 “Oscars” for the development of ultrananocrystalline diamond mechanical seals. Coated with a thin nanomaterial of diamond fragments, the UNCD seals are considered stronger, smoother, more energy efficient and durable than silicon-carbide seals commonly found in today’s mechanical pumps.

Creating a diamond-based coating for pump seals used to control the flow of fluids and industrial slurries might seem like an extravagance, but not when you consider the consequences of malfunctioning seals. Seal failure is a primary cause of downtime and energy loss in processing plants, and leaky seals can lead to the loss of costly raw material and, in more serious scenarios, the seepage of untold quantities of hazardous chemicals and liquids into the environment. Hence, the importance of seals being rugged, wear resistant, frictionless and able to withstand heat and cold. Thanks to their surfaces being coated with UNCD, Argonne’s award-winning seals excel in all of these areas. UNCD is a nanomaterial invented by Argonne scientists that consists of diamond grains “two to five nanometers in diameter,” according to Argonne’s website. In fact, the lab’s website reveals that Argonne and a German industrial partner received an earlier R&D 100 award in 2003 for creating “a large-area deposition system that applied UNCD to semiconductor wafers.”

As R&D magazine explains, however, “the potential for making mechanical seals with it [UNCD] was underestimated at the time.” Even though scientists recognized the benefits of diamond coatings, they still had to overcome hurdles before putting them to use. For one thing, fabricating diamond-based nanocoatings is complicated and integrating them with other materials is even more complex. Cost also is a consideration. “To make a difference in manufacturing,” Argonne’s website explains, “new mechanical pump seals would have to be priced to compete with the less efficient silicon-carbide seals they would replace.” Funded by the Department of Energy’s Industrial Technologies Program, Argonne researchers finally surmounted all of these challenges, discovering a proprietary method for adapting and applying UNCD to mechanical seals in a manner that would accommodate their mass production. “I think that’s a big part of what makes this such a huge breakthrough,” says John Hryn, Argonne’s principal process development engineer. “We not only managed to integrate UNCD with the pump seal, but we also made it in a way where it could be manufactured at a large production facility and would be cost-effective for those who would want to use it.” In describing the self-polishing UNCD seals, R&D magazine says their “grain boundaries are a mixture of diamond- and graphite-bonded carbon,” resulting in a “film hardness of 97 GPa” and a “0.02 in air” coefficient of friction. Hryn credits Argonne spin-off, Advanced Diamond Technologies in Romeoville, Ill., for developing the seals’ mass-production platform, and John Crane Inc. in Morton Grove, Ill., for testing the seals and verifying their superiority over conventional silicon-carbide seals.

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