Tribological properties of sandfish skink's scale under micro loads (Part 2) - Tribological properties under mN loads

It is thought that sandfish skink, living in desert, has scales that have low friction and high wear resistance properties. In previous study, we investigated the tribological properties of sandfish's scales under micro newton loads. It is found that the scales have low adhesion forces, which would lead to the low friction property. In this study, a tribological property of sandfish's scales was investigated under milli newton loads (of 3, 5, 10 mN) to investigate wear resistance property mainly. Tribological tests were also carried out using polytetrafluoroethylene (PTFE) and polyimide (PI) for comparison with the scales. Using a SUJ2 ball with a diameter of 1 mm, wear of sandfish scale was not occurred or much lower than those of PTFE and PI. When wear was not happened for sandfish's scale in the relative low contact pressure, a friction coefficient of the sandfish's scale was lower than those of PI and PTFE. When a tungsten probe with an apex diameter of 5 urn was used in which contact pressure was huge with compare to that using the SUJ2 ball, wears on all samples were observed. In the relative high contact pressure, the friction coefficient of sandfish's scale was higher than that of PI. Under the milli newton loads, the microstructure of the sandfish's scale did not affect its tribological property.