Microstructure and tribological characterization of coated PEEK-based polymers

Al-Rjoub, Abbas (author), Cavaleiro, Albano (author), Kalin, Mitjan (author), Emami, Nazanin (author)

This study investigates the tribological performance of chromium nitride (CrN)-coated polyether ether ketone (PEEK) polymers. CrN coating was deposited by physical vapor deposition (PVD) onto two commercially available substrates: neat PEEK and a modified PEEK. The suitability of the coated substrates for tribological applications was evaluated using ball-on-disc tests against stainless-steel (SS) counterparts. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the high thermal stability of the PEEK substrates, ensuring compatibility with low-temperature coating deposition. Microstructural analysis revealed dense and continuous CrN coatings with an average thickness of ~1.5 µm on both substrates. Tribological results of selected PEEK-based polymers showed that under the applied load of 2 N, uncoated PEEK substrates exhibited lower coefficients of friction (COFs) and smoother wear tracks compared with coated samples. In contrast, under the applied load of 4 N, CrN-coated PEEK substrates demonstrated reduced friction and improved stability relative to uncoated PEEK. This behavior is attributed to load-induced tribo-oxidation and the formation of a chromium-oxide-rich tribolayer that stabilized the sliding interface and suppressed adhesive wear. Overall, the results demonstrate that CrN coatings significantly enhance the load-bearing capacity and tribological performance of selected PEEK substrates under applied load of 4 N, highlighting their potential for advanced lightweight engineering applications requiring improved wear resistance.

• Language: English
• Keywords: coated PEEK, CrN, tribological performance, coating friction and wear
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: Str. 1-22
• Numbering: Vol. 16, issue 8, art. 899
• PID: 20.500.12556/RUL-185929
• UDC: 539.92:678.7
• ISSN on article: 2079-6412
• DOI: 10.3390/coatings16080899
• COBISS.SI-ID: 288588547
• Publication date in RUL: 24.08.2026

Record is a part of a journal

• Title: Coatings
• Shortened title: Coatings
• Publisher: MDPI AG
• ISSN: 2079-6412
• COBISS.SI-ID: 523035673

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: prevlečen PEEK, CrN, tribološke lastnosti, trenje in obraba prevleke