Insight Into Surface Texture-Induced Dual Effects on Friction of WC-Co Dry Sliding Against Continuous Carbon Fiber-Reinforced Thermoplastic and Thermosetting Composites

Abstract

To elucidate both positive and negative surface texture-induced effects on friction under dry conditions and to reveal polymer transfer properties on inert tungsten carbide-cobalt (WC-Co), tribological properties of line-, sawtooth-, dimple-, and triangle-textured WC-Co discs dry sliding against continuous carbon fiber-reinforced thermoplastic poly-ether-ether-ketone and thermosetting epoxy (CCF-PEEK and CCF-epoxy) pins were investigated in ambient atmosphere. Texture edges yielded a microcutting effect, resulting in frictional increase and material removal from the pin. Higher texture area density usually implied a stronger microcutting effect. Accumulated CCF-PEEK wear chips developed into a self-lubricious tribofilm that offset frictional increase, but CCF-epoxy wear chips could not evolve into tribofilms and the resultant abrasive wear increased friction. Reservoir effects of texture and reduction in real contact area were beneficial for frictional reduction, whereas they were insignificant compared with the microcutting effect. The findings suggest that a frictional counterpart with a self-lubricious component is crucial for the coefficient of friction (COF) reduction in the textured tribosystem under dry conditions. Surface texture does not necessary lead to frictional reduction, and further research should systematically analyze texture-induced dual effects on tribological performance.