Nanoscale friction behavior between montmorillonite and quartz: considering effects of cations, normal load and sliding velocity

Abstract

Abstract Nanoscale tribology between quartz and montmorillonite interface in soft clay is crucial for comprehending their engineering mechanism, which remains unclear in microscale. In this study, Molecular Dynamics (MD) simulation method was employed to investigate the nanoscale frictional properties between quartz and montmorillonite at dry state, where montmorillonite was set as substrate and quartz as sliding slider. The effects of normal load, interlayer cations, and sliding velocity on the frictional behavior were investigated and discussed. The simulation results indicated that the stick-slip effect during friction process was gradually weakened with increasing sliding velocity or decreasing normal load. The shear stress increased with the increasing normal load, exhibiting an approximately linear relationship. The order of friction coefficients of montmorillonite-quartz with different interlayer cations is Ca2+ > Zn2+ > Ni2+ > Pb2+ > Li+ > Rb+ > Cs+ > K+, illustrating that the friction coefficient of montmorillonite-quartz systems with divalent cations was greater than that with monovalent cations. The friction angle of montmorillonite-quartz with different interlayer cations vary from 6.96° to 17.28°. Moreover, the friction load roses linearly with the rising sliding velocity, indicating that the nanoscale friction is velocity-dependent.