Ultralow Wear Behavior of Iron–Cobalt-Filled PTFE Composites

Kylie E. Van Meter; Tomas F. Babuska; Christopher P. Junk; Kasey L. Campbell; Mark A. Sidebottom; Tomas Grejtak; Andrew B. Kustas; Brandon A. Krick

doi:10.1007/s11249-022-01679-z

Ultralow Wear Behavior of Iron–Cobalt-Filled PTFE Composites

Kylie E. Van Meter, Tomas F. Babuska, Christopher P. Junk, Kasey L. Campbell, Mark A. Sidebottom, Tomas Grejtak, Andrew B. Kustas, Brandon A. Krick

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

For the first time, we demonstrate that PTFE filled with iron–cobalt (FeCo) microparticles is an ultralow wear, magnetic, multifunctional tribological material. PTFE filled with 5 wt% of equiatomic, pre-alloyed FeCo powder resulted in steady-state wear rates of 2.8 × 10^–7 mm³/Nm, approaching that of PTFE-filled alumina. Comparable wear rates were not observed for PTFE filled separately with elemental iron (Fe) or cobalt (Co) microparticles. PTFE filled with either Fe or Co microparticles exhibited only incremental improvements in steady-state wear behavior when compared to unfilled PTFE (1 order of magnitude or less improvement). Particle size analysis and morphology indicate that the Fe and Co microparticles are strongly fused agglomerates (5–20 µm) made of smaller primary particles or features, while the FeCo microparticles are large (~ 40 µm), spherical, dense particles. IR spectroscopy shows that PTFE-FeCo composites form more tribochemical species than elemental Fe- or Co-filled composites, leading to the observed improvements in wear rate. The FeCo particles are surprisingly large as a filler for ultralow wear PTFE. From these results, we conclude that the fully dense, metallic, microscale, and intrinsically brittle FeCo particles may be friable and break down during sliding to reinforce and promote stable tribofilms, akin to the previously reported alumina particles in ultralow wear PTFE-alumina composites.

Original language	English
Article number	4
Journal	Tribology Letters
Volume	71
Issue number	1
DOIs	https://doi.org/10.1007/s11249-022-01679-z
State	Published - Feb 2023
Externally published	Yes

Funding

This material is based upon work supported by the National Science Foundation CMMI MEP #2027029 (Krick CAREER), National Science Foundation CMMI MEP #1463141 (Krick GOALI), and National Science Foundation Graduate Research Fellowship Program under grant #1449440 (Van Meter), #1452783 (Campbell), and #1842163 (Babuska). Support from the Sandia National Laboratories Laboratory Directed Research and Development (LDRD) program is acknowledged. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Funders	Funder number
National Science Foundation	CMMI MEP #1463141, 1449440, 1452783, 1842163, 2027029
U.S. Department of Energy
National Nuclear Security Administration	DE-NA0003525

Keywords

Cobalt
Friction
Iron
Iron–cobalt
Magnetic
PTFE
Ultralow wear
Wear

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10.1007/s11249-022-01679-z

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title = "Ultralow Wear Behavior of Iron–Cobalt-Filled PTFE Composites",

abstract = "For the first time, we demonstrate that PTFE filled with iron–cobalt (FeCo) microparticles is an ultralow wear, magnetic, multifunctional tribological material. PTFE filled with 5 wt% of equiatomic, pre-alloyed FeCo powder resulted in steady-state wear rates of 2.8 × 10–7 mm3/Nm, approaching that of PTFE-filled alumina. Comparable wear rates were not observed for PTFE filled separately with elemental iron (Fe) or cobalt (Co) microparticles. PTFE filled with either Fe or Co microparticles exhibited only incremental improvements in steady-state wear behavior when compared to unfilled PTFE (1 order of magnitude or less improvement). Particle size analysis and morphology indicate that the Fe and Co microparticles are strongly fused agglomerates (5–20 µm) made of smaller primary particles or features, while the FeCo microparticles are large (~ 40 µm), spherical, dense particles. IR spectroscopy shows that PTFE-FeCo composites form more tribochemical species than elemental Fe- or Co-filled composites, leading to the observed improvements in wear rate. The FeCo particles are surprisingly large as a filler for ultralow wear PTFE. From these results, we conclude that the fully dense, metallic, microscale, and intrinsically brittle FeCo particles may be friable and break down during sliding to reinforce and promote stable tribofilms, akin to the previously reported alumina particles in ultralow wear PTFE-alumina composites.",

keywords = "Cobalt, Friction, Iron, Iron–cobalt, Magnetic, PTFE, Ultralow wear, Wear",

author = "{Van Meter}, {Kylie E.} and Babuska, {Tomas F.} and Junk, {Christopher P.} and Campbell, {Kasey L.} and Sidebottom, {Mark A.} and Tomas Grejtak and Kustas, {Andrew B.} and Krick, {Brandon A.}",

note = "Publisher Copyright: {\textcopyright} 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.",

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AU - Van Meter, Kylie E.

AU - Babuska, Tomas F.

AU - Junk, Christopher P.

AU - Campbell, Kasey L.

AU - Sidebottom, Mark A.

AU - Grejtak, Tomas

AU - Kustas, Andrew B.

AU - Krick, Brandon A.

PY - 2023/2

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N2 - For the first time, we demonstrate that PTFE filled with iron–cobalt (FeCo) microparticles is an ultralow wear, magnetic, multifunctional tribological material. PTFE filled with 5 wt% of equiatomic, pre-alloyed FeCo powder resulted in steady-state wear rates of 2.8 × 10–7 mm3/Nm, approaching that of PTFE-filled alumina. Comparable wear rates were not observed for PTFE filled separately with elemental iron (Fe) or cobalt (Co) microparticles. PTFE filled with either Fe or Co microparticles exhibited only incremental improvements in steady-state wear behavior when compared to unfilled PTFE (1 order of magnitude or less improvement). Particle size analysis and morphology indicate that the Fe and Co microparticles are strongly fused agglomerates (5–20 µm) made of smaller primary particles or features, while the FeCo microparticles are large (~ 40 µm), spherical, dense particles. IR spectroscopy shows that PTFE-FeCo composites form more tribochemical species than elemental Fe- or Co-filled composites, leading to the observed improvements in wear rate. The FeCo particles are surprisingly large as a filler for ultralow wear PTFE. From these results, we conclude that the fully dense, metallic, microscale, and intrinsically brittle FeCo particles may be friable and break down during sliding to reinforce and promote stable tribofilms, akin to the previously reported alumina particles in ultralow wear PTFE-alumina composites.

AB - For the first time, we demonstrate that PTFE filled with iron–cobalt (FeCo) microparticles is an ultralow wear, magnetic, multifunctional tribological material. PTFE filled with 5 wt% of equiatomic, pre-alloyed FeCo powder resulted in steady-state wear rates of 2.8 × 10–7 mm3/Nm, approaching that of PTFE-filled alumina. Comparable wear rates were not observed for PTFE filled separately with elemental iron (Fe) or cobalt (Co) microparticles. PTFE filled with either Fe or Co microparticles exhibited only incremental improvements in steady-state wear behavior when compared to unfilled PTFE (1 order of magnitude or less improvement). Particle size analysis and morphology indicate that the Fe and Co microparticles are strongly fused agglomerates (5–20 µm) made of smaller primary particles or features, while the FeCo microparticles are large (~ 40 µm), spherical, dense particles. IR spectroscopy shows that PTFE-FeCo composites form more tribochemical species than elemental Fe- or Co-filled composites, leading to the observed improvements in wear rate. The FeCo particles are surprisingly large as a filler for ultralow wear PTFE. From these results, we conclude that the fully dense, metallic, microscale, and intrinsically brittle FeCo particles may be friable and break down during sliding to reinforce and promote stable tribofilms, akin to the previously reported alumina particles in ultralow wear PTFE-alumina composites.

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KW - Friction

KW - Iron

KW - Iron–cobalt

KW - Magnetic

KW - PTFE

KW - Ultralow wear

KW - Wear

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ER -

Ultralow Wear Behavior of Iron–Cobalt-Filled PTFE Composites

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