RT Journal Article
SR Electronic
T1 What is the origin of macroscopic friction?
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaav2268
DO 10.1126/sciadv.aav2268
VO 4
IS 12
A1 Sakuma, H.
A1 Kawai, K.
A1 Katayama, I.
A1 Suehara, S.
YR 2018
UL http://advances.sciencemag.org/content/4/12/eaav2268.abstract
AB What is the origin of molecular friction, and how can macroscopic friction be explained in terms of molecular friction? To elucidate the origins of molecular and macroscopic friction, we conducted density functional theory calculations and double-direct shear tests at normal stresses ranging from 5 to 60 MPa for mica surfaces. Frictional forces between mica surfaces were theoretically predicted to oscillate periodically every 30° of sliding direction, in agreement with previous experimental findings. This result affirms that the potential energy roughness of mica under sliding is the origin of molecular friction, which depends on the normal stress and sliding direction. The discovered mechanism of molecular friction can quantitatively explain experimentally observed macroscopic friction of mica when the presence of wear particles is taken into consideration.