High cycle fatigue and wear behavior of ta-C and a-C:H coated PEEK polymer spur gears under dry contact conditions

Mojškerc, Bor (author), Stiller, Tanja (author), Durjava, Aleš (author), Vukašinović, Nikola (author)

Diamond-like carbon (DLC) coatings are under investigation as a potential solution for extending the service life of polymer gears. This study examines the fatigue and wear behavior of polyetheretherketone (PEEK) polymer gears coated with tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H) at thicknesses of 2 μm and 5 μm. The gears were subjected to reference gear pair testing at 1.8 Nm torque under dry contact conditions in a climate-controlled environment. The PEEK substrate and the DLC coated gear failure mechanisms include both tooth flank and root fatigue fractures, with minor tooth surface wear observed. Although DLC coatings wore off relatively early when meshing with steel gears, the service life of the ta-C (5 μm) and a-C:H (5 μm) coated gears was approximately twice that of the PEEK substrate gears and ta-C (2 μm) coated gears. In addition, the a-C:H coatings caused minimal wear on the steel counterparts due to their higher sp2 hybridized graphite structure, whereas the ta-C coatings caused major wear due to their predominantly sp3 hybridized diamond structure. Overall, the results demonstrate that ta-C (5 μm) and a-C:H (5 μm) coatings significantly improve the durability and performance of PEEK polymer gears, highlighting their potential for demanding applications.

• Language: English
• Keywords: gears, PEEK, coatings, diamond-like carbon, fatigue, 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: 2025
• Number of pages: 13 str.
• Numbering: Vol. 152, art. 109009
• PID: 20.500.12556/RUL-175129
• UDC: 621.833:620.178
• ISSN on article: 0142-9418
• DOI: 10.1016/j.polymertesting.2025.109009
• COBISS.SI-ID: 253591811
• Publication date in RUL: 17.10.2025

Record is a part of a journal

• Title: Polymer testing
• Shortened title: Polym. test.
• Publisher: Elsevier
• ISSN: 0142-9418
• COBISS.SI-ID: 26155008

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: polimerni zobniki, PEEK, prevleke, DLC, utrujanje, obraba

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P2-0425
• Name: Decentralizirane rešitve za digitalizacijo industrije ter pametnih mest in skupnosti

• Funder: Other - Other funder or multiple funders
• Funding programme: Austrian Competence Center Program
• Project number: COMET PCCL-K1, project VII-3.11
• Name: Tribological characterization of bulk and surface modified gear wheel contacts