Page 184 - Handbook of Surface Improvement and Modification

11.1 Methods and mechanisms of improvement of the coefficient of friction 179

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sure and temperature distribution. A pull-through design supports uniform pressure dis-
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tribution.
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Table 11.2 contains data on friction coefficients of some polymeric materials.
Table 11.2. Friction coefficient of some polymers. [Data from Pei, XQ; Friedrich, K, Fric-
tion and Wear of Polymer Composites. Reference Module in Materials Science and
Materials Engineering, Elsevier 2016.]

Friction coefficient
Polymer
0.8 MPa m/s 2 MPa m/s
Polytetrafluoroethylene 0.16 0.17
Ultrahigh molecular weight polyethylene 0.20 0.19
Poly(ethylene terephthalate) 0.18 0.18
Polyamide-6 0.21 0.19
Polyoxymethylene 0.24 0.20
Polyetheretherketone 0.24 0.28

Figure 11.20. Scanning electron microscopy images of (a) Euploea mulciber (b) Papilioparis butterfly wings.
SEM images of fabricated (c) 66 (d) 123 (e) 182 textured surfaces. [Adapted, by permission, from Grewal, HS;
Pendyala, P; Shin, H; Cho, I-J; Yoon, E-S, Wear, 384-385, 151-8, 2017.]
Friction and adhesion become extremely important at nano- and micro-length scales,
modulating the durability of several nano/microelectromechanical systems (NEMS/
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MEMS). The friction and wetting behavior of textured surfaces derived by mimicking
the surface morphology of butterfly wing has been a subject of study (Figure 11.20). 22
Different contact aspect ratios were fabricated on silicon wafer using photolithography
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and deep reactive ion-etching techniques. The textured surface patterns were then coated
with polytetrafluoroethylene, diamond-like carbon, and fluorine incorporated diamond-