A Molecular Dynamics Study of Tribological Properties of Silicon Carbide as a Metal-Free Friction Material

Friction materials containing metal ingredients used in automotive industry can cause unfavorable environmental impacts. Existing laws and regulations require phase out of heavy metals in brake pads. Substitutions for metals in friction materials, however, may introduce operational safety issues. In the current study, a molecular dynamics model based on LAMMPS has been developed to study the effect of material composition, density and geometric configurations on the tribological, mechanical and thermal properties of silicon carbide under various contact conditions at the atomic level. Successful simulations are performed to predict the elastic modulus, thermal conductivity, wear rate and coefficient of friction, with the incorporation of interfacial contact between surface asperities. The predicted properties can help enhance the performance of engineered metal free friction materials against thermal-mechanical failures. The following factors have been taken into consideration in the model: elevated temperature, sliding speed, crystal orientation, particle size, degree of intersection, types of loading and surface contact. Some of the simulation results have been compared to the existing experimental data in the literature and satisfactory agreements are found. The molecular dynamics model developed in this work can also be modified to deal with other types of nonmetallic friction composites.