@article {1469,
	title = {Surface characterization of polytetrafluoroethylene (PTFE) transfer films during rolling-sliding tribology tests using X-ray photoelectron spectroscopy},
	journal = {Wear},
	volume = {261},
	number = {10},
	year = {2006},
	note = {ISI Document Delivery No.: 113XZTimes Cited: 4Cited Reference Count: 33Lu, X. Wong, K. C. Wong, P. C. Mitchell, K. A. R. Cotter, J. Eadie, D. T.},
	month = {Nov},
	pages = {1155-1162},
	type = {Article},
	abstract = {A disk-on-disk Amsler wear tester simulating the rolling-sliding motion and high pressure during wheel/rail contact, was used to study the wear performance of PTFE including its film transfer and material flow properties. The chemical composition of the transfer film formed on the wheel-disk surface at various test stages were analyzed by X-ray photoelectron spectroscopy (XPS). The friction curve of the PTFE films obtained on the Amsler can be divided into three regions, according to the friction level and disk surface morphology. Initially, there is a rapid increase of friction coefficient which is presumably accompanied by a fast material transfer from pre-coated rail-disk to the wheel-disk surfaces. In the second region, the friction remains stable throughout and the XPS results show the presence of PTFE on the wheel-disk surface which confirms a transfer of material between the two contact surfaces. In addition, the splitting of F 1s and C 1s photoelectron peaks of PTFE, as a result of a discrepancy in surface charging, suggests that the transfer film exists in two forms: thick patch and thin film. With an increase in rolling cycles, the thick patches become thinner, as well as its coverage reduces. By contrast, the thin film gains both in thickness and coverage. Using a simple model, the thin film is calculated to be only a few nanometers thick. At the beginning of the third region, only a thin film is left on the surface. Additional rolling leads to a rapid rise in friction and the transfer film thickness continues to decrease. The evidence supports the removal of PTFE out of the contact zone, and a high friction coefficient (mu = 0.6) is reached at the end of the test indicating an un-lubricated metal-metal contact. No major tribochemical reaction of PTFE is observed during this study. (c) 2006 Elsevier B.V. All rights reserved.},
	keywords = {(XPS), COMPOSITES, CONTACT, friction, friction modifier, INTERFACE, LUBRICATION, MODIFIER, polytetrafluoroethylene (PTFE), SURFACE, third body, TOP, WEAR, WHEEL-RAIL ADHESION, wheel/rail contact, X-ray photoelectron spectroscopy},
	isbn = {0043-1648},
	url = {<Go to ISI>://000242632600012},
	author = {Lu, X. and Wong, K. C. and Wong, P. C. and Mitchell, K. A. R. and Cotter, J. and Eadie, D. T.}
}
@article {988,
	title = {Surface-induced ordering of nematics in an external field: The strong influence of tilted walls},
	journal = {Physical Review Letters},
	volume = {92},
	number = {18},
	year = {2004},
	note = {ISI Document Delivery No.: 818XNTimes Cited: 8Cited Reference Count: 19},
	month = {May},
	pages = {4},
	type = {Article},
	abstract = {Microscopic theory is used to investigate surface-induced order in a model nematic subjected to an external orienting field. The wall-particle interaction tends to orient particles perpendicular to the surface. It is shown that if the wall is tilted at similar to45degrees to the field, the reorientational effects can be an order of magnitude larger than those observed for perpendicular or parallel orientations. The surprising observation is associated with the breaking of a particular bulk symmetry. A possible practical application of the tilted geometry is briefly discussed.},
	keywords = {CONTACT, FLUID, LIQUID-CRYSTALS, ORNSTEIN-ZERNIKE EQUATION, PHASE, SUBSTRATE, TRANSITIONS},
	isbn = {0031-9007},
	url = {<Go to ISI>://000221277900033},
	author = {Sokolovska, T. G. and Sokolovskii, R. O. and Patey, G. N.}
}
