Influence of test equipment and working conditions on the coefficient of friction values

Frictions between isotopic single-crystal diamonds was compared by means of AFM and simulations, and we found that friction of l3C diamond is lower than that of 12C by 2∼3%. This result is consistent with simulation and theoretical analysis that ascribes friction to an energy-dissipation process. The friction reduction of 13C diamond results from inhibition of the energy-dissipative lattice vibration by a heavier atom mass. This finding indicates that friction can be changed by properties of bulk atoms of a solid, not only by the surface. It also implies that recent sub-micron fabrication techniques (e.g., multi-film stack and surface texturing) that can be modify the bulk properties of a solid has possible to control friction in terms of tuning of the energy-dissipation process, as a new way that does not rely on the modification of surface properties.