Molecular Dynamics Study of Fretting Wear Characteristics of Silicon Nitride Bearings

Abstract

To study fretting wear characteristics of silicon nitride bearing. Atomic model of surface fretting wear of silicon nitride bearing is constructed by molecular dynamics method and deep learning self-fitting potential function. First principles are used to match silicon nitride crystal parameters; Dynamic analysis of fretting wear process of nanoscale silicon nitride bearing is realized. Experiment shows that friction force in the Z direction is a maximum of 3.5 nN. The output potential energy 2.31 × 10⁷ eV is 1.63 times that of the y-axis, which is main factor causing the fretting wear. The force perpendicular to the direction of roller and the collar of silicon nitride bearings should be avoided in the process of using or transporting the bearings. Silicon nitride bearing fretting wear process is non-transient elastic stress-strain, along the rolling plane extension, in the roller rolling direction to form a sharp angle shape high strain linear region. Bearing Z direction damage degree increased; Silicon nitride bearing surface layer has 22.47% of the N─Si bond fracture. The study of the fretting wear characteristics of silicon nitride ceramic bearings has a reference value for reducing the surface friction of silicon nitride bearings and improving the life of silicon nitride bearings.