Revealing tribo-oxidation mechanisms of the copper-WC system under high tribological loading

The near-surface structural and chemical changes were investigated for pure copper against a tungsten carbide (WC) sphere during high tribological loading. Fundamental stages are identified in the Cu-WC tribo-system: (i) high tribological stress promotes grain refinement to the ultra-fine grains regime in the very beginning; (ii) nucleation of extremely fine (similar to 3 nm) oxygen-enriched Cu nano particles in the nearsurface layer and subsequent growth of the Cu2O oxide; (iii) formation of continuous nanostructured mixing layer with heterogeneous Cu and O distribution in the late stage. Near-surface mechanical mixing is presumably the main contribution to chemical modifications under high tribological loading. Our findings shed atomic-insights into intricate tribochemical modifications, one of the most intriguing phenomena in material-oriented tribology. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study revealed complex structural and chemical changes between pure copper and tungsten carbide under high tribological loading, including grain refinement, nucleation of oxygen-enriched Cu nano particles, growth of Cu2O oxide, and formation of a nanostructured mixing layer with heterogeneous Cu and O distribution.