News Column

Patent Issued for Inert Wear Resistant PTFE-Based Solid Lubricant Nanocomposite

June 4, 2014

By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Sawyer, W. Gregory (Gainesville, FL); Burris, David L. (Gainesville, FL), filed on January 11, 2013, was published online on May 20, 2014.

The assignee for this patent, patent number 8728993, is University of Florida Research Foundation, Inc. (Gainesville, FL).

Reporters obtained the following quote from the background information supplied by the inventors: "Polytetrafluoroethylene (PTFE) exhibits desirable tribological characteristics, including low friction, high melting temperature and chemical inertness. Based on these characteristics, PTFE is a frequently used solid lubricant both as a filler and matrix material. Without a filler, however, PTFE suffers from a relatively high wear rate, generally precluding its use in frictional applications, including use as a bearing material.

"As a matrix material, PTFE has been successfully filled with various nanoparticles, including alumina, zinca, and carbon nanotubes. Regarding alumina filling, Sawyer et al. [Sawyer, W. G., Freudenburg, K. D., Bhimaraj, P., and Schadler, L. S., (2003), 'A Study on the Friction and Wear of Ptfe Filled with Alumina Nanoparticles,' Wear, 254, pp. 573-580] discloses 38 nm substantially spherical shaped Al.sub.2O.sub.3 filler particles for improving the wear performance of PTFE. The wear resistance of this nanocomposite was reported to increase monotonically with filler wt %, eventually being 600 times more wear resistant than unfilled PTFE at a loading of 20 wt. % Al.sub.2O.sub.3. Although the wear performance provided by PTFE/alumina nanocomposites disclosed by Sawyer et al. represents a major improvement over PTFE, the high filler percentage required to reach the desired wear level significantly raises the cost of the nanocomposite. In addition, for certain applications wear rates lower than 600 times better than PTFE are desirable and may even be required. Accordingly, a PTFE nanocomposite is needed which provides improved wear resistance, while at the same time requiring a lower filler percentage as compared to the PTFE nanocomposites disclosed by Sawyer et al."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "A PTFE-based composite material comprises a PTFE comprising a major phase filled with a metal oxide minor phase. The major phase is intermixed with the metal oxide minor phase, wherein the minor phase comprises a plurality of irregularly shaped metal oxide nanoparticles. The minor phase can comprise 1 to 10 wt. % of said composite, such as 3 to 7 wt. %. In one embodiment, the metal oxide nanoparticles have shapes characteristic of milled particles. The metal oxide can comprise aluminum oxide. Regarding performance, the composite can provide a steady state wear rate of K

"A method of forming wear resistant composite materials comprises the steps of blending nanoscale metal oxide particles and PTFE particles, wherein the metal oxide particles are irregular shaped nanoparticles, and heating the nanoscale metal oxide particles and PTFE particles to form a nanocomposite. The heating step can comprise compression molding. A jet milling apparatus is preferably used for the blending step. In one embodiment, the metal oxide comprises aluminum oxide."

For more information, see this patent: Sawyer, W. Gregory; Burris, David L.. Inert Wear Resistant PTFE-Based Solid Lubricant Nanocomposite. U.S. Patent Number 8728993, filed January 11, 2013, and published online on May 20, 2014. Patent URL:

Keywords for this news article include: Lubricants, Nanoparticle, Nanocomposite, Nanotechnology, Emerging Technologies, University of Florida Research Foundation Inc.

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Source: Journal of Engineering

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