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  • 1.
    Rodiouchkina, Maria
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Dry sliding wear and friction behavior of self-lubricating polymer composite bearing materials under extreme operating conditions2017Conference paper (Other academic)
  • 2.
    Rodiouchkina, Maria
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Berglund, Kim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Dry sliding wear and friction behavior of self-lubricating polymer composite bearing materials under extreme operating conditions2017Conference paper (Refereed)
  • 3.
    Rodiouchkina, Maria
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Berglund, Kim
    Larsson, Roland
    Influence of Counter Surface Roughness andOrientation on the Tribological Behavior of Self-lubricating Bearing Materialsin Dry Sliding Conditions2018Conference paper (Refereed)
    Abstract [en]

    Bearing failures account for a significant share of the operational economical losses in hydropower plants. In Kaplan turbines, the most critical components are the self-lubricating polymer composite bearings used for regulation of the guide vanes and the turbine blades as they operate at high loads, low sliding speeds and small oscillatory movements. Reducing the sliding wear and friction of these bearings would offer a positive impact on both the economy and environment including longer useful life, lower operational costs and higher efficiency.

    In this study, influence of counter surface roughness and orientation on the tribological behavior of bearing materials used in hydropower applications are investigated using a linear reciprocating block-on-block configuration under high pressure and low sliding speed. Surface roughness was measured using white light interferometry. SEM and EDS analysis were used to investigate the polymer surfaces and the transfer film formation.

    Results from this study indicates that too smooth surfaces result in higher friction and wear of the counter surface while rougher surfaces have a negative effect on the wear of the polymers. It can be concluded that counter surface topography has a significant influence on the tribological behavior of these bearings and the effect differs between materials.

  • 4.
    Rodiouchkina, Maria
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Berglund, Kim
    Larsson, Roland
    Influence of operational and surface conditionson the tribological performance of self-lubricating polymer composite bearingmaterials used in hydropower applications2019In: Influence of operational and surface conditionson the tribological performance of self-lubricating polymer composite bearingmaterials used in hydropower applications, 2019Conference paper (Refereed)
    Abstract [en]

    In hydropower applications, self-lubricating polymer composite bearings has proven to be a good and environmentally friendly replacement for the traditionally used grease lubricated bronze bearings. However, in recent years, end users have experienced several bearing failures due to more demanding operating conditions due to integration of fluctuating renewable energy sources, e.g. wind and solar power, into the electric power systems.

    The aim of this work is to summarize and highlight important findings regarding the influence of various parameters on the tribological behaviour of these bearing materials using a linear reciprocating pin-on-disc configuration.

    Results indicates that low sliding speed and high nominal pressure offer the best performance for these bearing materials, with a reduction in frictional loses with up to 45% and almost three times lower wear. Furthermore, friction and wear can be reduced even more by optimizing the surface topography and hardness of the shaft.

  • 5.
    Rodiouchkina, Maria
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Berglund, Kim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Forsberg, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rodushkin, Ilia
    ALS Laboratory Group, ALS Scandinavia AB.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Material Characterization and Influence of Sliding Speed and Pressure on Friction and Wear Behavior of Self-Lubricating Bearing Materials for Hydropower Applications2018In: Lubricants, ISSN 2075-4442, Vol. 6, no 2, article id 39Article in journal (Refereed)
    Abstract [en]

    Nowadays, hydropower plants are forced to have more frequent power control and the self-lubricated bearings used in the applications are one of the most critical components affected by the continuously changing operating conditions. In this study, microstructure and composition of two commercially available bearing materials (Orkot TXM Marine and Thordon ThorPlas) used in hydropower turbines were studied. In addition, the influence of sliding speed and applied pressure on the friction and wear behavior of the materials was investigated systematically for dry sliding conditions. The bearing materials were characterized using X-ray microtomography, Nuclear Magnetic Resonance (NMR) spectroscopy and Inductively Coupled Plasma–Sector Field Mass Spectrometry (ICP-SFMS) techniques. Friction and wear tests were carried out with a polymer pin sliding against a stainless steel (SS2333) plate with a linear reciprocating motion. Test conditions were: room temperature, 9–28 MPa pressure and 10–40 mm/s sliding speed ranges. Surface analysis of the polymer pins and the wear tracks were performed by optical profilometry, Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) techniques. Test results show that, for both materials, the coefficient of friction (COF) is decreasing at higher pressures. Surface analysis reveals higher concentrations of solid lubricants in the transfer layers formed at higher pressures, explaining the decrease in COF. Furthermore, the specific wear rate coefficients are increasing at higher sliding speeds, especially at lower pressures. Results of this study demonstrate that, under dry sliding conditions, changes in sliding speed and pressure have a significant influence on the tribological behavior of these bearing materials.

  • 6.
    Rodiouchkina, Maria
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Pelcastre, Leonardo
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Lind, Jonna
    Berglund, Kim
    Kassman Rudolphi, Åsa
    Larsson, Roland
    Tribological behaviour of self-lubricating polymercomposite bearing materials during long-time dry sliding2019In: Tribological behaviour of self-lubricating polymercomposite bearing materials during long-time dry sliding, 2019Conference paper (Refereed)
    Abstract [en]

    Thermosets and thermoplastics containing PTFE are used in marine and hydropower applications due to their long service life and self-lubricity in dry and water-lubricated contacts. Their tribological performance is usually extrapolated from short, accelerated tests, which induces risks of inaccurate or incorrect interpretation.

    The aim of this study is to investigate the tribological behaviour and development of transfer layers during long sliding tests (160 hours), corresponding to years of operation. To mimic operational shutdowns, the tests were stopped every 20 hours to study the evolution of the surface topography and transfer layers.

    The wear rates of both materials decreased significantly with time. For the thermoplastic, COF decreased due to accelerated material transfer after 80 hours, highlighting the importance of long duration tests. The thermoset showed the highest transfer amount after 20 h and cause severe abrasive wear on the counter surface accompanied by a COF increase.

  • 7. Rudnytskyj, André
    et al.
    Rodiouchkina, Maria
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Hultqvist, Tobias
    Berglund, Kim
    Larsson, Roland
    Contact mechanics and wear of self-lubricating polymer bearings used in hydropowerapplications2018Conference paper (Refereed)
1 - 7 of 7
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