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Research Papers: Mixed and Boundary Lubrication

Novel One-Component Anisole- and Hydroxyl-Terminated Perfluoropolyethers for Boundary Lubrication

[+] Author and Article Information
Ao Fan

Western Digital Corporation,
5601 Great Oaks Parkway,
San Jose, CA 95119-1003
e-mail: fan.ao@wdc.com

Connie Wiita

Western Digital Corporation,
5601 Great Oaks Parkway,
San Jose, CA 95119-1003
e-mail: connie.wiita@wdc.com

Robert J. Waltman

Western Digital Corporation,
5601 Great Oaks Parkway,
San Jose, CA 95119-1003
e-mail: robert.waltman@wdc.com

1Corresponding author.

Contributed by the Tribology Division of ASME for publication in the Journal of Tribology. Manuscript received December 20, 2018; final manuscript received March 7, 2019; published online April 16, 2019. Assoc. Editor: Bart Raeymaekers.

J. Tribol 141(6), 062101 (Apr 16, 2019) (8 pages) Paper No: TRIB-18-1519; doi: 10.1115/1.4043181 History: Received December 20, 2018; Accepted March 09, 2019

The tribological properties of some novel single component perfluoropolyether (PFPE) boundary lubricants with chemically integrated mixture end groups are investigated. Chemically integrated mixture end groups composed of hydroxyl- and anisole-terminated PFPE boundary lubricant films on the –(CF2CF2CF2O)– main chain are reported. These PFPE-based boundary lubricants explore a new method by which single component PFPE lubricants with mixture end groups might be used to tailor boundary film properties instead of using physical mixtures of two or more PFPEs with different end groups. Lubricant transfer to the low-flying read/write head, head wear, and siloxane adsorption as a function of PFPE film thickness and of type are compared. Normalization of the data to the monolayer fraction instead of film thickness allows direct comparison between anisole- and hydroxyl-terminated PFPEs. Lubricant transfer to the head and head wear are independent of the functional end groups. Siloxane adsorption decreases with increasing anisole substitution of the hydroxyl groups. One-component PFPEs with mixed end groups provide a methodology by which boundary film properties could be adjusted.

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References

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Figures

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Fig. 1

The chemical structures of (a) D-2OH, (b) D-3OH, (c) D-4OH, (d) DART-1S, and (e) DART-2

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Fig. 2

The film thickness correlation between the PFPE IR band maximum and ESCA for the PFPEs used in these experiments

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Fig. 3

The experimental chamber used to expose disks to siloxanes using Taica rubber as the source. The infrared spectra compare authentic polydimethylsiloxane and the outgassing components from the Taica gel that decorate the disk surface.

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Fig. 4

The (a) dispersive and (b) polar components of the surface energy as a function of film thickness for DART-1S and DART-2 on an amorphous carbon surface

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Fig. 5

The dispersive, polar, and total disjoining pressure as a function of film thickness for (a) DART-1S and (b) DART-2

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Fig. 6

Ellipsometric images of the disk surface as a function of film thickness for DART-1S and DART-2

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Fig. 7

Changes in the film thickness as a function of burnish passes for (a) DART-1S and (b) DART-2

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Fig. 8

Summary plot of the average monolayer film thickness for D-4OH, DART-1S, and DART-2 as a function of number average molecular weight

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Fig. 9

Lubricant pick-up as a function of PFPE: (a) film thickness, (b) disjoining pressure, and (c) monolayer fraction

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Fig. 10

Head wear rate as a function of PFPE: (a) film thickness and (b) monolayer fraction

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Fig. 11

The bonded fraction for 10–11 Å PFPE films as a function of time under ambient storage

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Fig. 12

The adsorbed siloxane counts (SiC3H9) as a function of PFPE: (a) film thickness and (b) monolayer fraction

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