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  1. Article: On the Microstructural, Mechanical and Tribological Properties of Mo-Se-C Coatings and Their Potential for Friction Reduction against Rubber.

    Caessa, Jorge / Vuchkov, Todor / Yaqub, Talha Bin / Cavaleiro, Albano

    Materials (Basel, Switzerland)

    2021  Volume 14, Issue 6

    Abstract: Friction and wear contribute to high energetic losses that reduce the efficiency of mechanical systems. However, carbon alloyed transition metal dichalcogenide (TMD-C) coatings possess low friction coefficients in diverse environments and can self-adapt ... ...

    Abstract Friction and wear contribute to high energetic losses that reduce the efficiency of mechanical systems. However, carbon alloyed transition metal dichalcogenide (TMD-C) coatings possess low friction coefficients in diverse environments and can self-adapt to various sliding conditions. Hence, in this investigation, a semi-industrial magnetron sputtering device, operated in direct current mode (DC), is utilized to deposit several molybdenum-selenium-carbon (Mo-Se-C) coatings with a carbon content up to 60 atomic % (at. %). Then, the carbon content influence on the final properties of the films is analysed using several structural, mechanical and tribological characterization techniques. With an increasing carbon content in the Mo-Se-C films, lower Se/Mo ratio, porosity and roughness appeared, while the hardness and compactness increased. Pin-on-disk (POD) experiments performed in humid air disclosed that the Mo-Se-C vs. nitrile butadiene rubber (NBR) friction is higher than Mo-Se-C vs. steel friction, and the coefficient of friction (CoF) is higher at 25 °C than at 200 °C, for both steel and NBR countersurfaces. In terms of wear, the Mo-Se-C coatings with 51 at. % C showed the lowest specific wear rates of all carbon content films when sliding against steel. The study shows the potential of TMD-based coatings for friction and wear reduction sliding against rubber.
    Language English
    Publishing date 2021-03-10
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma14061336
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Effect of Annealing Heat Treatment on the Composition, Morphology, Structure and Mechanical Properties of the W-S-N Coatings.

    Yaqub, Talha Bin / Al-Rjoub, Abbas / Khalid, Hafiza Ayesha / Yaqoob, Khurram / Fernandes, Filipe / Cavaleiro, Albano

    Materials (Basel, Switzerland)

    2022  Volume 15, Issue 12

    Abstract: Alloyed-transition metal dichalcogenide (TMD) coatings have been under investigation as multi-environment lubricants for the past few decades. These coatings display very low coefficient of friction properties at elevated temperatures. Studies on the ... ...

    Abstract Alloyed-transition metal dichalcogenide (TMD) coatings have been under investigation as multi-environment lubricants for the past few decades. These coatings display very low coefficient of friction properties at elevated temperatures. Studies on the annealing of these low-friction coatings are missing in the literature. For the first time, in this study, the annealing of the W-S-N dry lubricant coatings was carried out to study its effects on the composition, morphology, crystal structure and hardness of the coatings. The W-S-N coatings were deposited by direct current (DC) reactive magnetron sputtering. The analysis was carried out for as-deposited, 200 °C and 400 °C annealed coatings. The as-deposited coatings have N content in the range of 0-25.5 at. %. The coatings are compact and the densification increased with the increase in N-alloying. All the coatings are crystalline except the highest N-alloyed coating which is X-ray amorphous. A maximum hardness of 8.0 GPa was measured for the coating alloyed with 23 at. % N. Annealing did not affect the composition and morphology of the coatings, while some variations were observed in their crystal structure and hardness. The maximum hardness increased from 8 GPa to 9.2 GPa after 400 °C annealing of the 23 at. % N-alloyed coating.
    Language English
    Publishing date 2022-06-09
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2487261-1
    ISSN 1996-1944
    ISSN 1996-1944
    DOI 10.3390/ma15124088
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Mechanical Properties and Vacuum Tribological Performance of Mo–S–N Sputtered Coatings

    Hebbar Kannur, Kaushik / Yaqub, Talha Bin / Pupier, Christophe / Héau, Christophe / Cavaleiro, Albano

    ACS applied materials & interfaces. 2020 Aug. 25, v. 12, no. 38

    2020  

    Abstract: MoS₂ is the most widely used dry lubricant for low friction applications in vacuum environments. However, due to its lamellar nature it exfoliates during sliding, leading to high wear, high coefficient of friction (COF), and low stability. Here, we ... ...

    Abstract MoS₂ is the most widely used dry lubricant for low friction applications in vacuum environments. However, due to its lamellar nature it exfoliates during sliding, leading to high wear, high coefficient of friction (COF), and low stability. Here, we report the mechanical properties and the vacuum (10–⁴ Pa) tribological performance of nitrogen-alloyed transition-metal-dichalcogenide (TMD-N) coatings. The coatings were deposited using a hybrid deposition method, that is, reactive direct current (DC) sputtering of MoS₂ target assisted by an additional plasma source. The tribological tests were performed at relatively low contact stresses to replicate real industrial needs. The interaction between different mating surfaces (coating versus steel, coating versus coating) has been reported. Additionally, the effects of loads on the sliding properties were also studied for coating versus coating interactions. A maximum hardness of 8.9 GPa was measured for the 37 atom % N-alloyed coating. In all mating conditions, the pure MoS₂ coating had COF in the range of 0.1–0.25 and the least specific wear rates were found to be 3.0 × 10–⁶ mm³/N·m for flat and 2.5 × 10–⁶ mm³/N·m for cylinder. As compared to MoS₂ coating, the COF and specific wear rates decreased with N additions. The COF was in the range of 0.05–0.1 for Mo–S–N coatings, while coating versus coating displayed the lowest specific wear rates (8.6 × 10–⁸ mm³/N·m for flat and 4.4 × 10–⁸ mm³/N·m for cylinder). Finally, the increase in load resulted in a decrease of COF, but an increase in the wear rate was observed. The detailed mechanism behind the behavior of the COF for the different mating conditions was presented and discussed. This work brings some important issues when testing transition metal dichalcogenide-based coatings under low contact stress conditions more appropriate for simulating real service applications.
    Keywords friction ; hardness ; lubricants ; steel
    Language English
    Dates of publication 2020-0825
    Size p. 43299-43310.
    Publishing place American Chemical Society
    Document type Article
    Note NAL-AP-2-clean
    ISSN 1944-8252
    DOI 10.1021/acsami.0c12655
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: Mechanical Properties and Vacuum Tribological Performance of Mo-S-N Sputtered Coatings.

    Hebbar Kannur, Kaushik / Yaqub, Talha Bin / Pupier, Christophe / Héau, Christophe / Cavaleiro, Albano

    ACS applied materials & interfaces

    2020  Volume 12, Issue 38, Page(s) 43299–43310

    Abstract: ... ...

    Abstract MoS
    Language English
    Publishing date 2020-09-09
    Publishing country United States
    Document type Journal Article
    ISSN 1944-8252
    ISSN (online) 1944-8252
    DOI 10.1021/acsami.0c12655
    Database MEDical Literature Analysis and Retrieval System OnLINE

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