| Autor: |
Soltanahmadi S; iFS, School of Mechanical Engineering , University of Leeds , Leeds LS2 9JT , U.K., Charpentier T; School of Chemical and Process Engineering , University of Leeds , Leeds LS2 9JT , U.K., Nedelcu I; SKF Research & Technology Development , 3430 DT Nieuwegein , The Netherlands., Khetan V; iFS, School of Mechanical Engineering , University of Leeds , Leeds LS2 9JT , U.K., Morina A; iFS, School of Mechanical Engineering , University of Leeds , Leeds LS2 9JT , U.K., Freeman HM; School of Chemical and Process Engineering , University of Leeds , Leeds LS2 9JT , U.K., Brown AP; School of Chemical and Process Engineering , University of Leeds , Leeds LS2 9JT , U.K., Brydson R; School of Chemical and Process Engineering , University of Leeds , Leeds LS2 9JT , U.K., van Eijk MCP; SKF Research & Technology Development , 3430 DT Nieuwegein , The Netherlands., Neville A; iFS, School of Mechanical Engineering , University of Leeds , Leeds LS2 9JT , U.K. |
| Abstrakt: |
In wind turbine gearboxes, (near-)surface initiated fatigue is attributed to be the primary failure mechanism. In this work, the surface fatigue of a hydrogenated tungsten carbide/amorphous carbon (WC/aC:H) thin-film was tested under severe cyclic tribo-contact using polyalphaolefin (PAO) and PAO + zinc dialkyldithiophosphate (ZDDP) lubricants. The film was characterized in terms of its structure and chemistry using X-ray diffraction, analytical transmission electron microscopy, including electron energy loss spectroscopy (EELS), as well as X-ray photoelectron spectroscopy (XPS). The multilayer carbon thin-film exhibited promising surface fatigue performance showing a slight change in the hybridization state of the aC:H matrix. Dehydrogenation of the thin-film and subsequent transformation of cleaved C-H bonds to nonplanar sp 2 carbon rings were inferred from EELS and XPS results. While tribo-induced changes to the aC:H matrix were not influenced by a nanometer-thick ZDDP reaction-film, the rate of oxidation of WC and its oxidation state were affected. While accelerating surface fatigue on a steel surface, the ZDDP-tribofilm protected the WC/aC:H film from surface fatigue. In contrast to the formation of polyphosphates from ZDDP molecules on steel surfaces, it appeared that on the WC/aC:H thin film surface, ZDDP molecules decompose to ZnO, suppressing the oxidative degradation of WC. |
