Page 188 - Handbook of Surface Improvement and Modification

11.1 Methods and mechanisms of improvement of the coefficient of friction 183

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characteristics of UHMWPE on ice. The
optimum amount of additive (2.5 wt%)
reduced the friction coefficient only at tem-
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o
peratures greater than -7 C. Figure 11.25
shows the effect of temperature on coeffi-
cient of friction of UHMWPE with and
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without the additive.
Friction behavior of nano-textured
polyimide was measured by atomic force
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microscope colloidal probe. The flat poly-
imide and silicon dioxide nanoparticle-tex-
Figure 11.25. The effect of temperature on the coeffi- tured polyimide films were prepared by the
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cient of friction of UHMWPE and UHMWPE contain- spin-coating technique. The nano-tex-
ing 2.5% perfluoropolyalkylether sliding on ice with tured polyimide surface significantly
speed of 1.96 m/s. [Adapted, by permission, from Stam-
boulides, C; Englezos, P; Hatzikiriakos, SG, Tribology reduced the adhesive and friction forces as
Intl., 57, 177-83, 2013.] compared to the flat polyimide surface
because the nano-texture reduced the con-
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tact area between the sample surface and the probe.
Wear and friction behavior of polyetheretherketone filled with graphene, tungsten
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disulfide, and CNT nanoparticles have been studied. The type and the morphology of the

Figure 11.26. FE-SEM images of fractured cross-sections of nanocomposites taken at magnification of 20,000;
(a) fullerene-like tungsten disulfide, (b) needle-like tungsten disulfide, (c) carbon nanotubes, and (d) graphene.
[Adapted, by permission, from Kalin, M; Zalaznik, M; Novak, S, Wear, 332-333, 855-62, 2015.]