Researchers from the Laboratory for Tribology and Interface Nanotechnology (TINT) have developed a new nanocoating strategy that significantly improves the durability of high-performance polymer components. The study, published in Tribology International (IF 6.9), demonstrates how advanced solid-lubricant coatings can dramatically reduce friction and wear in polyether ether ketone (PEEK), a widely used engineering polymer.
PEEK is increasingly used in demanding engineering applications such as automotive systems, aerospace components, and biomedical devices because of its excellent strength-to-weight ratio, chemical stability, and thermal resistance. However, when used in moving mechanical systems, the material often suffers from relatively high friction and limited wear resistance, which restricts its use in high-load sliding applications.
To address this challenge, the research team applied carbon-alloyed tungsten disulfide (WSC) nanocoatings onto PEEK surfaces using a magnetron sputtering process. The coatings were carefully engineered with optimized architectures, including adhesion-enhancing interlayers, allowing the coating to remain stable during sliding contact. This surface-engineering approach created a durable low-friction interface on the polymer surface.
Tribological testing revealed substantial performance improvements. The coated polymer surfaces showed up to 34% lower friction and more than 98% reduction in wear compared with uncoated PEEK. The enhanced performance was linked to the formation of a stable carbon-rich tribolayer during sliding, which protects the polymer surface and promotes smooth motion between contacting parts.
“Advanced nanostructured coatings can fundamentally change how lightweight polymers behave in mechanical systems,” said Dr. Talha Bin Yaqub, lead author of the study. Professor Mitjan Kalin, who led the research, noted that such surface-engineering strategies could enable polymers like PEEK to replace heavier metal components in future machines.
The findings highlight a scalable pathway for integrating solid-lubricant nanocoatings with polymer components. This could benefit a wide range of applications, including polymer gears, bearings, and sliding elements in energy-efficient transportation and industrial machinery.
Figure: Overview of the experimental approach used to enhance the durability and tribological performance of PEEK polymer using carbon-alloyed tungsten disulfide (WSC) coatings. (a) Schematic illustration of the magnetron sputtering deposition system showing the arrangement of WS₂, carbon, and chromium targets around the rotating specimen holder used for coating synthesis and the conceptual representation of the DC magnetron sputtering process, where Ar⁺ ions generated in the plasma bombard the target, ejecting atoms that subsequently deposit on the substrate to form the WSC coating.
(b) Reciprocating sliding test configuration and coating architectures investigated in this study, comparing uncoated PEEK, WSC-coated PEEK without interlayer (PEEK/WSC), and WSC-coated PEEK with Cr interlayer and gradient layer (PEEK/Cr/WSC).
(c-d) Summary of tribological performance efficiency and durability, showing the reduction in friction coefficient and specific wear rate achieved with the optimized coating architecture, demonstrating improved durability of the coated polymer surface.