Friction characteristics between two nanostripe surfaces.

In order to elucidate the friction characteristics of different types of periodic surface patterns, friction tests were performed on nanostripe surfaces fabricated on cylindrical surfaces with a curvature radius of 150 mm at sliding speeds of 0.7 μm/s–0.7 mm/s. On the nanostripe surfaces, microgrooves were arrayed at a pitch of 6 μm, while nanogrooves were formed on the ridges between neighboring microgrooves at a pitch of approximately 500 nm. The friction coefficient was the lowest at 0.06 when a nanostripe surface was rubbed against a smooth silicon surface at a speed of 0.7 μm/s and the sliding direction was parallel to the grooves. For combinations consisting of two nanostripe surfaces, the maximum friction coefficient was measured for the configuration wherein the grooves of the nanostripes on the two surfaces were perpendicular to the sliding direction, and for the configuration wherein the grooves of the nanostripes on the two surfaces were orthogonal to each other. In the case of the former configuration, the sticking force generated by the slopes of the microgrooves had a determining effect on the measured friction force. • Cross-cylinder contact configuration enabled a contact area larger than pattern size. • Micro-patterned surfaces were fabricated by photolithography with thin Si wafers. • Constant friction coefficients were obtained by microgrooves under lubricated condition. • Nanogrooves persisted in wear traces due to varying wear rates of constituent metals. [ABSTRACT FROM AUTHOR]