The interface between hard disk and slider involves mechanical and tribochemical processes between the hard carbon overcoat of the disk, the lubricant, and the carbon coated or uncoated slider surface. These processes have been studied by two related X-ray techniques—Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy and Photoemission Electron Microscopy (PEEM) using X-rays. NEXAFS allows studying the elemented composition and chemical bonding in a material, whereas PEEM combines this ability with imaging of the sample. Lubricated and unlubricated disks were worn under various conditions using carbon coated and uncoated sliders. The wear tracks on the hard disks were investigated using PEEM to find chemical and elemental changes caused by the wear. Local NEXAFS spectra taken in wear tracks using the PEEM microscope show no chemical changes on unlubricated disks, just a reduction of the hard carbon overcoat thickness. On lubricated disks remarkable chemical modifications of the lubricants caused by the wear are observed if the disks failed the wear tests. The chemical changes are manifested in a formation of various new carbon-oxygen (mostly carboxylic) bonds in the wear tracks and in a strong reduction of the amount of fluorine and carbon. The chemical modifications were only found inside the wear tracks and are clearly caused by the wear. It was found that lubricant degradation is not solely a mechanical process of molecule scission but accompanied by oxidation reactions. The chemical changes were strongly correlated to the tribological behavior of the disks: the worse the disks performed in the wear tests, the stronger were the chemical modifications.

1.
Anders
S.
,
Bhatia
C. S.
,
Fong
W.
,
Lo
R. Y.
, and
Bogy
D. B.
,
1998
a, “
Application of Cathodic Arc Deposited Amorphous Hard Carbon Films to the Head/Disk Tribology
,”
Mat. Res. Sot: Symp. Proc
, Vol.
517
, pp.
371
382
.
2.
Anders, S., Stammler, T., Fong, W., Bogy, D. B., Bhatia, C. S., and Sto¨hr, J., 1998g, “Investigation of Slider Surfaces After Wear Using Photoemission Electron Microscopy,” J. Vac. Sci. Technol., Vol. A17, in print.
3.
Anders, S., Stammler, T., Bhatia, C. S., Sto¨hr, J., Fong, W., Chen, C.-Y., and Bogy, D. B., 1999, “Study of Hard Disks and Slider Surfaces Using X-Ray Photoemission Electron Microscopy and Near-Edge X-ray Absorption Fine Structure Spectroscopy,” Mat. Res. Soc. Symp. Proc, Vol. 517, pp. 415–420.
4.
Anders, S., Scheinfein, M., Duarte, R., Cossy, A., Renner, T., Padmore, H., and Diaz, J., 1997, “Design of a High-Resolution X-ray Photoemission Electron Microscope (PEEM2) for ALS Beamline 7.3,1.1,” Lawrence Berkeley National Laboratory, Internal Report, unpublished.
5.
Bhatia
C. S.
,
Fong
W.
,
Chen
C.-Y.
,
Bogy
D. B.
,
Anders
S.
,
Stammler
Th.
, and
Sto¨hr
J.
,
1998
, “
Tribochemistry at The Head/Disk Interface
,”
IEEE Trans. Magn.
, Vol.
35
, pp.
910
915
.
6.
Coffman
F. L.
,
Cao
R.
,
Pianetta
P. A.
,
Kapoor
S.
,
Kelly
M.
, and
Terminello
L.
,
1996
, “
Near-Edge X-Ray Absorption of Carbon Materials for Determining Bond Hybridization in Mixed sp2sp3 Bonded Materials
,”
Appl. Phys. Lett.
, Vol.
69
, pp.
568
570
.
7.
Cossy-Favre
A.
,
Diaz
J.
,
Liu
Y.
,
Brown
H. R.
,
Samant
M. G.
,
Stohr
J.
,
Hanna
A. J.
,
Anders
S.
, and
Russel
T. P.
,
1998
, “
X-PEEM Study on Surface Orientation of Stylized and Rubbed Polyimides
,”
Macromolecules
, Vol.
31
, pp.
4957
4962
.
8.
Diaz, J., Anders, S., Cossy-Favre, A., Samant, M., and Sto¨hr, J., 1998, “Enhanced Electron Emission from Oxidized Regions on Amorphous Carbon Films Studied by X-ray Spectro-Microscopy,” J. Vac. Sci. Technol, submitted for publication.
9.
Jaouen
M.
,
Tourillon
G.
,
Delafond
J.
,
Junqua
N.
, and
Hug
G.
,
1995
, “
A NEXAFS Characterization of Ion-Beam-Assisted Carbon-Sputtered Thin Films
,”
Diamond Relat. Mater.
, Vol.
4
, pp.
200
206
.
10.
Kang, H. J., Zhao, Q., Taike, F. E., Peretti, D. J., Dekoven, B. M., Morgan, T. A., Fischer, D. A., Hsu, S. M., and Bhatia, C. S., 1998, “The Use of Cyclic Phosphazene Additives to Enhance the Performance of the Head/Disk Interface,” 1998 ASME/STLE Tribology Conference Preprint No. 98-TC-5E-1, STLE, Park Ridge, IL.
11.
Kasai
P. H.
,
Wang
W. T.
, and
Wheeler
P.
,
1991
, “
Degradation of Perfluoropoly-ethers Catalyzed by Aluminum Oxide
,”
Appl. Surf. Sci.
, Vol.
51
, pp.
201
211
.
12.
Lin
J. L.
,
Bhatia
C. S.
, and
Yates
J. T.
,
1995
, “
Thermal and Electron Stimulated Chemistry of Fomblin-ZDOL Lubricant on a Magnetic Disk
,”
J. Vac. Sci. Technol. A
, Vol.
13
, pp.
163
168
.
13.
Mate, M., and Wilson, R. S., 1998, “Grand Unified Theory of Fluorocarbon Polymer Mobility on Disk Surfaces,” Amer. Chem. Soc. Meeting, Boston, to be published.
14.
Min
B. G.
,
Choi
J. W.
,
Brown
H. R.
,
Yoon
D. Y.
,
O’Conner
T. M.
, and
Jhon
M. S.
,
1995
, “
Spreading Characteristics of Thin Liquid Films of Perfluoropoiyal-kylethers on Solid Surfaces. Effects of Chain-End Functionality and Humidity
,”
Tribol. Lett.
, Vol.
1
, pp.
225
232
.
15.
Novotny
V. J.
,
Karis
T. E.
, and
Johnson
N. W.
,
1992
, “
Lubricant Removal, Degradation, and Recovery on Particulate Magnetic Recording Media
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
114
, pp.
61
67
.
16.
Novotny
J. V.
,
Pan
X. H.
, and
Bhatia
C. S.
,
1994
, “
Tribochemistry at Lubricated Interfaces
,”
J. Vac. Sci. Technol. A
, Vol.
12
, pp.
2879
2886
.
17.
Ohta
T.
,
Seki
K.
,
Yokohama
T.
,
Morisada
I.
, and
Edamatsu
K.
,
1990
, “
Polarized XANES Studies of Oriented Polyethylene and Fluorinated Polyethylenes
,”
Physica Scripta
, Vol.
41
, pp.
150
153
.
18.
Pharr
G. M.
,
Callahan
D. L.
,
McAdams
S. D.
,
Tsui
T. Y.
,
Anders
S.
,
Anders
A.
,
Ager
J. W.
,
Brown
I. G.
,
Bhatia
C. S.
,
Silva
S. R. P.
, and
Robertson
J.
,
1996
, “
Hardness, Elastic Modulus, and Structure of Very Hard Carbon Films Produced by Cathodic—Arc Deposition with Substrate Pulse Biasing
,”
Appl. Phys. Lett.
, Vol.
68
, pp.
779
781
.
19.
Samant
M.
,
Sto¨hr
J.
,
Brown
H. R.
,
Russel
T. P.
,
Sands
J. M.
, and
Kumar
S. K.
,
1996
, “
NEXAFS Studies on the Surface Orientation of Buffed Polyimides
,”
Macromolecules
, Vol.
29
, pp.
8334
8342
.
20.
Stammler, T., Anders, S., Padmore, H., Sto¨hr, J., Scheinfein, M., and Ade, H., 1998, “High-Resolution Photoemission Electron Microscopy at the Advanced Light Source,” Mat. Res. Soc. Symp. Proc., Vol. 524, pp. 25–30.
21.
Sto¨hr, J., 1992, NEXAFS Spectroscopy, Springer Verlag, New York.
22.
Sto¨hr
J.
,
Samant
M. G.
,
Cossy-Favre
A.
,
Diaz
J.
,
Momoi
Y.
,
Odahara
S.
, and
Nagata
T.
,
1998
, “
Microscopic Origin of Liquid Crystal Alignment on Rubbed Polymer Surfaces
,”
Macromolecules
, Vol.
31
, pp.
1942
1946
.
23.
Tonner
B. P.
,
Dunham
D.
,
Droubay
T.
,
Kikuma
J.
,
Denlinger
J.
,
Rotenberg
E.
, and
Warwick
T.
,
1995
, “
The Development of Electron Spectromicroscopy
,”
J. Electron Spectroscopy Relat. Phenom.
, Vol.
75
, pp.
309
332
.
24.
Tonner
B. P.
,
Dunham
D.
,
Droubay
T.
, and
Pauli
M.
,
1997
, “
A Photoemission Microscope with a Hemispherical Capacitor Energy Filter
,”
J. Electron Spectrosc. Relat. Phenom.
, Vol.
84
, pp.
211
229
.
25.
Wei
J. J.
,
Fong
W.
,
Bogy
D. B.
, and
Bhatia
C. S.
,
1998
, “
The Decomposition Mechanisms of a Perfluoropolyether at the Head/Disk Interface of Hard Disk Drives
,”
Tribol. Lett.
, Vol.
5
, pp.
203
209
.
26.
Yun
X. H.
,
Bogy
D. B.
, and
Bhatia
C. S.
,
1996
, “
Wear of Hydrogenated Carbon Coated Disks by Carbon Coated and Uncoated AI302/TiC in Ultra High Vacuum
,”
IEEE Trans. Magn.
, Vol.
32
, pp.
3669
3671
.
27.
Yun
X. H.
,
Bogy
D. B.
, and
Bhatia
C. S.
,
1997
, “
Tribochemical Study of Hydrogenated Carbon Coatings with Different Hydrogen Content Levels in Ultra High Vacuum
,”
ASME JOURNAL OF TRIBOLOGY
, Vol.
119
, pp.
437
442
.
28.
Zhao, Q., Kang, H. J., Fu, L., Talke, F. E., Peretti, D. J., and Morgan, T. A., 1998, “Tribological Study of Phosphazene-Type Additives in Perfluoropolyether Lubricant for Hard Disk,” 1998 ASME/STLE Tribology Conference Preprint No. 98-TC-4C-I, STLE, Park Ridge, IL.
29.
Ziegler
Ch.
,
Schedel-Niedrig
Th.
,
Beamson
O.
,
Clark
D. T.
,
Salaneck
W. R.
,
Sotobayashi
H.
, and
Bradshaw
A. M.
,
1994
, “
X-Ray Absorption Study of Highly Oriented Poly(tetrafluoroethylene) Thin Films
,”
Langmuir
, Vol.
10
, pp.
4399
4402
.
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