Velocity-Dependent Dynamics of Friction and Wear

Understanding the relationship between sliding velocity, temperature, friction, and wear is of fundamental importance in materials science and engineering. Here, we explore sliding friction and wear of a silicon carbide nano-asperity sliding over a silicon carbide substrate for a broad range of temperatures and velocities using molecular dynamics simulations. Our study reveals three distinct friction regimes over four velocity decades: velocity-weakening at moderate velocities, velocity-strengthening at high velocities, and an additional velocity-strengthening behavior at very low velocities and elevated temperatures. We theoretically describe these findings with physics-based friction models. For the low-velocity regime, we refine the Prandtl-Tomlinson model by incorporating a logarithmic aging mechanism that accounts for surface diffusion-driven contact evolution. For the high-velocity regime, we introduce a linear viscous friction model with an Arrhenius temperature dependence. These models demonstrate strong agreement with the molecular dynamics simulation results in their respective velocity regimes. We then explore wear mechanisms, distinguishing between atomic attrition at low velocities and collective material removal at high velocities, thus providing a comprehensive framework for understanding the velocity and temperature dependence of nanoscale friction and wear of silicon carbide.