Adhesive wear mechanisms in the presence of weak interfaces: Insights from an amorphous model system

Engineering wear models are generally empirical and lack connections to the\nphysical processes of debris generation at the nanoscale to microscale. Here,\nwe thus analyze wear particle formation for sliding interfaces in dry contact\nwith full and reduced adhesion. Depending on the material and interface\nproperties and the local slopes of the surfaces, we find that colliding surface\nasperities can either deform plastically, form wear particles, or slip along\nthe contact junction surface without significant damage. We propose a mechanism\nmap as a function of material properties and local geometry, and confirm it\nusing quasi-two-dimensional and three-dimensional molecular dynamics and\nfinite-element simulations on an amorphous, siliconlike model material. The\nframework developed in the present paper conceptually ties the regimes of weak\nand strong interfacial adhesion together and can explain that even unlubricated\nsliding contacts do not necessarily lead to catastrophic wear rates. A salient\nresult of the present paper is an analytical expression of a critical length\nscale, which incorporates interface properties and roughness parameters.\nTherefore, our findings provide a theoretical framework and a quantitative map\nto predict deformation mechanisms at individual contacts. In particular,\ncontact junctions of sizes above the critical length scale contribute to the\ndebris formation.\n