Enhancing the tribological performance of polyether ether ketone (PEEK) polymer using carbon-alloyed transition metal dichalcogenide coatings

The demand for light-weight polymeric materials such as polyether ether ketone (PEEK) is increasing for advanced engineering components, like polymeric gears. However, the intrinsic limitations of PEEK, including high friction, poor wear resistance, and rapid surface degradation restrict its larger adoption. This work is dedicated towards enhancing the dry sliding performance of PEEK via surface modifications. Direct current magnetron sputtered (DCMS) carbon-alloyed tungsten disulfide (WSC) coatings having C content of ∼52 at. % were deposited on PEEK polymer substrates at low power. Modifications of coating architecture were obtained by depositing coatings with and without inter/gradient layers. Comprehensive post-deposition characterization included chemical composition, cross-section and surface morphology, crystal structure, detailed chemical bonding, and coatings-PEEK adhesion investigations. The coatings were uniform, compact, amorphous, and provided complete surface alteration of PEEK with sufficient coating-polymer adhesion. Under ambient air sliding, the WSC coating with inter/gradient layer architecture exhibited the best performance, by reduction in friction coefficient (COF) and specific wear rate up to ∼34.3 % and ∼98.3 %, respectively relative to the uncoated PEEK. Post sliding Raman and X-ray photoelectron spectroscopy (XPS) revealed that C dominated the role in the reduction of COF and wear through the formation of a stable, partially graphitized tribolayer. This work establishes a scalable pathway for integrating solid-lubricant coatings on polymeric components, opening new opportunities for their reliable use in high-load and energy-efficient industrial systems.