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  • 51.
    Glavatskih, Sergei
    et al.
    Luleå University of Technology, Division of Machine Elements.
    McCarthy, Donald
    Sherrington, Ian
    Further transient test results for a pivoted-pad thrust bearing2004In: Transient processes in tribology: proceedings of the 30th Leeds-Lyon Symposium on Tribology held at INSA de Lyon Villeurbanne, France, 2nd-5th September 2003, 2004, Vol. 301-312, p. 301-312Conference paper (Refereed)
    Abstract [en]

    Evolution of friction torque in a pivoted-pad thrust pad bearing, as well as collar and shaft temperatures and pressure profiles in transient conditions, have been investigated in [1]. The present paper reports further transient test results for the same thrust bearing with an outer diameter of 228.6mm and 60% offset pivoted pads, operated in fully flooded mode. In this study, a complete set of bearing main performance parameters, including bearing pad and collar temperatures, oil film thickness and friction torque are obtained by means of a high-speed data acquisition system. Evolution of these parameters as a result of sudden variations in rotational speed and load are presented and analysed. Results are generalised in terms of Fourier number and compared with published numerical data.

  • 52.
    Glavatskih, Sergei
    et al.
    Luleå University of Technology, Division of Machine Elements.
    Mordukhovich, G
    A torque transmitting device having a dimpled friction plate2007Patent (Other (popular science, discussion, etc.))
  • 53.
    Glavatskih, Sergei
    et al.
    Luleå University of Technology, Division of Machine Elements.
    Norrby, Thomas
    Torbacke, Marika
    Byheden, Åke
    Long term experience with environmentally adapted oils in hydrodynamic bearings of hydroelectric power plants2006In: Proceedings of the 23rd IAHR Symposium on Hydraulic Machinery and Systems, 2006Conference paper (Refereed)
  • 54.
    Glavatskih, Sergei
    et al.
    Luleå University of Technology, Division of Machine Elements.
    Sherrington, I.
    Tribotronics an active approach to the condition monitoring of tribological components in wind turbines2010In: COMADEM 2010 - Advances in Maintenance and Condition Diagnosis Technologies Towards Sustainable Society, Proc. 23rd Int. Congr. Condition Monitoring and Diagnostic Engineering Management, 2010, Vol. 711-714, p. 711-714Conference paper (Refereed)
    Abstract [en]

    In this paper we describe an active approach to the control of tribological components called "tribotronics". The structure and operation of a tribotronic system is described. The main advantage of these systems is that they contain actuators that allow changes/adjustments in component performance to be made in response to feedback (condition monitoring) signals in near real time. This approach can potentially address a developing problem at an early stage while providing a significant efficiency and cost savings through the reduction of on-site maintenance. Suggestions about how these systems could be usefully implemented in wind turbines are made.

  • 55.
    Glavatskih, Sergei
    et al.
    Luleå University of Technology, Division of Machine Elements.
    Torbacke, M.
    Byheden, Åke
    EALs for hydropower applications, Part 1: laboratory and full scale fluid film bearing tests2006In: Automotive and industrial lubrication: 15th International Colloquium Tribology ; January 17 - 19, 2006 in Stuttgart/Ostfildern, Germany, 2006, Vol. 134-, p. 143-Conference paper (Refereed)
    Abstract [en]

    Laboratory experiments and full scale tests are conducted to verify and to quantify the advantages of the environmentally adapted oils in hydrodynamic lubrication in terms of operating film thickness, bearing power loss, and operating temperature. Four different oils were studied. Environmentally adapted PAO and ester base ISO VG46 oils were selected from Group IV and V stocks, respectively. Mineral ISO VG68 oil was selected as the reference oil. Mineral ISO VG46 oil was chosen for comparison. Ester base oil provided the best bearing operating characteristics in terms of the developed oil film, pad temperature, and power loss. Thus, it was chosen for the further tests in large full scale bearings. Environmentally adapted ester base oil ISO VG46 provided much better performance than traditionally used mineral oil ISO VG68. Compared to the mineral oil power loss and bearing temperatures are reduced while minimum oil film remains the same. 

  • 56.
    Glavatskih, Sergei
    et al.
    Luleå University of Technology, Division of Machine Elements.
    Wasilczuk, M.
    Fillon, M.
    Performance peculiarities of PTFE-faced tilting-pad thrust bearings2004In: Improvement of bearing performance under severe operating conditions: 3rd EDF/LMS Poitiers Workshop FUTUROSCOPE, 2004Conference paper (Refereed)
    Abstract [en]

    Application of PTFE composites as pad facing allows for a significant improvement in tilt pad thrust bearing performance under severe operating conditions. Many applications of PTFE lined thrust bearings are known, primarily in water turbines in Russia and China, but recently a lot of interest in this kind of pad facing is observed in other countries, as well. This paper is a short overview of the peculiarities in bearing performance caused by some specific properties of PTFE composites. Known techniques for bonding PTFE composites to steel backing are first discussed. The PTFE bonding method utilized in Russia results in an intentionally increased resilience of the bearing surface. The effect of compliant nature of the PTFE on oil film geometry is considered. Another important aspect of using PTFE facing is the thermal insulation of the pad, minimizing its thermal distortions. The effect of minimized thermal distortions, being an advantage for large thrust bearing of water turbines, but, interestingly, not in all applications, is examined. Tribological (friction and wear) aspects of using PTFE layer are also discussed. Additional advantages of using PTFE as a substitute for babbitt are addressed as well. Finally, techniques for monitoring conditions in the PTFE bearings are described.

  • 57. Golchin, A.
    et al.
    Nguyen, T. D.
    De Baets, P.
    Prakash, B.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Effect of shaft roughness and pressure on friction of polymer bearings in water2013In: 5th World Tribology Congress, WTC 2013, 2013, Vol. 4, p. 3153-3156Conference paper (Refereed)
  • 58. Golchin, A.
    et al.
    Simmons, G. F.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Prakash, B.
    Tribological behaviour of polymeric materials in water-lubricated contacts2013In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 227, no 8, p. 811-825Article in journal (Refereed)
    Abstract [en]

    This study aims at investigating the tribological behaviour of several unfilled polymer materials sliding against 316L stainless steel in distilled water. The tests were carried out in a unidirectional pin-on-disc configuration with an initial apparent contact pressure of 5MPa at room temperature. The worn surfaces were examined using scanning electron microscopy and energy dispersive spectroscopy techniques and the wear mechanisms were discussed. These studies indicate the occurrence of tribocorrosion of stainless steel during sliding against polypropylene. It is inferred that the frictional behaviour of the polymers is determined by both their wettability and solubility in water, where generally an increased hydrophobicity and relative energy difference with regard to water results in lower friction. The results from friction and wear tests show overall superior tribological performance of ultrahigh molecular weight polyethylene compared with the other polymeric materials in water.

  • 59. Golchin, Arash
    et al.
    Nguyen, Tan Dat
    De Baets, Patrick
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Prakash, Braham
    Effect of shaft roughness and pressure on friction of polymer bearings in water2014In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 228, no 4, p. 371-381Article in journal (Refereed)
    Abstract [en]

    In this study, the frictional behavior of selected commercially available unfilled polymers, namely, polyether ether ketone, polytetrafluoroethylene, polyethylene terephthalate, and ultra-high molecular weight polyethylene against an Inconel shaft was investigated using a journal bearing test configuration in water-lubricated sliding contact. Dynamic friction curves were obtained for various shaft roughness values and polymer combinations. The results showed a significant influence of shaft surface roughness on running-in and steady state friction in water-lubricated conditions. Contact angle measurements revealed a significant increase in wettability of Inconel counterfaces. The X-ray photoelectron spectroscopy (XPS) analysis of the surfaces suggests formation of a reaction layer on worn Inconel surfaces when sliding against the polymers. The influences of counter surface roughness and load on frictional response of polymers were studied through intermittent tests by obtaining dynamic and breakaway friction maps for different polymer materials, shaft roughness values, and pressure combinations. In general, a trend of decreasing friction was obtained with increasing contact pressure; however, the materials' frictional responses to variations in counter surface roughness were different. These results indicate that although a reduced counter surface roughness may be beneficial for dynamic friction of polymers in all lubrication regimes, it can adversely affect the materials' breakaway friction response.

  • 60. Golchin, Arash
    et al.
    Simmons, Gregory F
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Break-away friction of PTFE materials in lubricated conditions2010In: 14th Nordic Symposium on Tribology : NORDTRIB 2010, 2010Conference paper (Refereed)
    Abstract [en]

    This study investigates the tribological characteristics at the initiation of sliding (break-away friction) of several polytetrafluoroethylene (PTFE) based materials including virgin PTFE (PP), PTFE filled with 25% black glass (PG), PTFE filled with 40% Bronze (PB), PTFE filled with 25% Carbon (PC), and PTFE filled with 20% glass fibre and 5% Molybdenum disulphide (PM), as well as standard white-metal Babbitt (BA) in lubricated sliding contact with a steel counter-face. Experiments were carried out using a reciprocating tribo-meter in the block on plate configuration with the specific goal of determining the friction characteristics at break-away under varying conditions. Apparent contact pressures of 1 to 8 MPa were applied with oil temperature levels of 25° to 85°C. Bronze- and carbon-filled PTFE and virgin PTFE were found to provide generally lower break-away friction and less variation in break-away friction over the course of testing than the other tested materials. Break-away friction tests after an extended stop under loading found bronze- and carbon-filled PTFE and virgin PTFE to be minimally affected by the extended stop whereas Babbitt produced a significant increase in break-away friction in the first cycle after stopping. Break-away friction for the four tested materials after an extended stop returned to pre-stop values after 1 stroke.

  • 61. Golchin, Arash
    et al.
    Simmons, Gregory F.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Break-away friction of PTFE materials in lubricated conditions2011In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 48, p. 54-62Article in journal (Refereed)
    Abstract [en]

    This study investigates the tribological characteristics at initiation of sliding (break-away friction) of several polytetrafluoroethylene based materials. Four PTFE composites, pure PTFE, and white metal were tested in a reciprocating tribo-meter with the block on plate configuration against a steel counter-surface. Apparent contact pressure and oil temperature were varied from 1 to 8 MPa and 25 to 85 Â°C respectively. SEM investigations revealed wear patterns of the PTFE materials and the abrasive nature of hard fillers. Bronze filled, carbon filled, and pure PTFE were found to provide lower break-away friction and less variation over the course of testing and generally superior properties.

  • 62.
    Hjalmarsson, Nicklas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Attana AB, Stockholm, SE-11419, Sweden.
    Bergendal, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Attana AB, Stockholm, SE-11419, Sweden.
    Wang, Yong-Lei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Munavirov, Bulat
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Wallinder, Daniel
    Attana AB, SE-11419 Stockholm, Sweden..
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Department of Electrical Energy, Metals, Mechanical Constructions and Systems, Ghent University, Ghent, B-9000, Belgium.
    Aastrup, Teodor
    Attana AB, SE-11419 Stockholm, Sweden..
    Atkin, Rob
    Univ Western Australia, Sch Mol Sci, Perth, WA 6009, Australia..
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, Stockholm, SE-50115, Sweden.
    Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil2019In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 35, no 48, p. 15692-15700Article in journal (Refereed)
    Abstract [en]

    The quartz crystal microbalance (QCM) has been used to study how the interfacial layer of an ionic liquid dissolved in a polar oil at low weight percentages responds to changes in applied potential. The changes in surface composition at the QCM gold surface depend on both the magnitude and sign of the applied potential. The time-resolved response indicates that the relaxation kinetics are limited by the diffusion of ions in the interfacial region and not in the bulk, since there is no concentration dependence. The measured mass changes cannot be explained only in terms of simple ion exchange; the relative molecular volumes of the ions and the density changes in response to ion exclusion must be considered. The relaxation behavior of the potential between the electrodes upon disconnecting the applied potential is more complex than that observed for pure ionic liquids, but a measure of the surface charge can be extracted from the exponential decay when the rapid initial potential drop is accounted for. The adsorbed film at the gold surface consists predominantly of ionic liquid despite the low concentration, which is unsurprising given the surtactant-like structures of (some of) the ionic liquid ions. Changes in response to potential correspond to changes in the relative numbers of cations and anions, rather than a change in the oil composition. No evidence for an electric field induced change in viscosity is observed. This work shows conclusively that electric potentials can be used to control the surface composition, even in an oil-based system, and paves the way for other ion solvent studies.

  • 63. Hjalmarsson, Nicklas
    et al.
    Bergendal, Erik
    Wang, Yong-Lei
    Wallinder, Daniel
    Attana AB, 11419 Stockholm, Sweden.
    Glavatskih, Sergei
    Aastrup, Teodor
    Attana AB, 11419 Stockholm, Sweden.
    Atkin, Rob
    Priority Research Centre for Advanced Fluids and Interfaces, The University of Newcastle, Callaghan, Australia .
    Rutland, Mark W
    Electro-responsive surface composition and kinetics of an ionic liquid in a polar oilManuscript (preprint) (Other academic)
  • 64.
    Hjalmarsson, Nicklas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wallinder, Daniel
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Univ Ghent, Dept Mech Construct & Prod, B-9052 Zwijnaarde, Belgium.
    Atkin, Rob
    Aastrup, Teodor
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute Sweden, Stockholm, Sweden.
    Weighing the surface charge of an ionic liquid2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 38, p. 16039-16045Article in journal (Refereed)
    Abstract [en]

    Electrochemical quartz crystal microbalance has been used to measure changes in the composition of the capacitive electrical double layer for 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate, an ionic liquid, in contact with a gold electrode surface as a function of potential. The mass difference between the cation and anion means that the technique can effectively "weigh" the surface charge accurately with high temporal resolution. This reveals quantitatively how changing the potential alters the ratio of cations and anions associated with the electrode surface, and thus the charge per unit area, as well as the kinetics associated with these interfacial processes. The measurements reveal that it is diffusion of co-ions into the interfacial region rather than expulsion of counterions that controls the relaxation. The measured potential dependent double layer capacitance experimentally validates recent theoretical predictions for counterion overscreening (low potentials) and crowding (high potentials) at electrode surfaces. This new capacity to quantitatively measure ion composition is critical for ionic liquid applications ranging from batteries, capacitors and electrodeposition through to boundary layer structure in tribology, and more broadly provides new insight into interfacial processes in concentrated electrolyte solutions.

  • 65. Javed, Muhammad Asadullah
    et al.
    Ahola, Susanna
    Hakansson, Par
    Mankinen, Otto
    Aslam, Muhammad Kamran
    Filippov, Andrei
    Shah, Faiz Ullah
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Antzutkin, Oleg N.
    Telkki, Ville-Veikko
    Y Structure and dynamics elucidation of ionic liquids using multidimensional Laplace NMR2017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 80, p. 11056-11059Article in journal (Refereed)
  • 66. Jourak, Amir
    et al.
    Cervantes, Michel
    Cupillard, Samuel
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    CFD analysis of a journal bearing with a microgroove on the shaft2008In: Proceedings of the 19th International Symposium on Transport Phenomena (ISTP-19): Reykjavik, Iceland, August 17-21, 2008 / [ed] Sigurdur Brynjolfsson, Olafur Petur Palsson, Jong H. Kim, 2008Conference paper (Refereed)
    Abstract [en]

    Journal bearings are used in many applications. An increase of their load carrying capacity and/or decrease of their losses may allow for savings of an enormous amount of energy. One way to enhance the characteristics of journal bearings is to modify the surface texture of the stator. The purpose of the present study is to investigate the influence of a textured rotor on journal bearing characteristics. Computational Fluid Dynamics is used to model the flow between the rotor and the journal. The full Navier-Stokes equations are solved under unsteady conditions with the commercial software ANSYS CFX 11. A two-dimensional geometry is used to model the bearing. In order to make a simulation, a separate rotor and stator are made and are attached to each other using a rotor-stator interface. Firstly, a single mesh for the smooth journal bearing is used to evaluate possible numerical artefacts created by the interface. The results illustrate a difference of 2.8 % in the load carrying capacity. Simulation with a dimpled rotor followed. Comparison between a dimpled rotor and smooth rotor shows no significant increase in load carrying capacity of the journal bearing when thermal effects are not taken into account.

  • 67. Kusnetsov, E
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    On power loss reduction in journal bearings2011In: Condition Monitoring, Performance Improvement and Safe Operation of Bearings, 2011Conference paper (Refereed)
  • 68. Kusnetsov, E
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Fillon, M
    The effect of PTFE lining on plain journal bearing characteristics2010In: Improvement of Bearing Performance and Evaluation of Adverse Conditions, 2010Conference paper (Refereed)
  • 69. Kuznetsov, Evgeny
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Dynamic characteristics of a 2 axial groove journal bearing with a PTFE lining2008In: Lubricants, materials and lubrication engineering: 16th International Colloquium Tribology ; January 15 - 17, 2008 in Stuttgart/Ostfildern, Germany / [ed] Wilfried Bartz, 2008Conference paper (Refereed)
  • 70.
    Kuznetsov, Evgeny
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). COMSOL LLC, Russian Federation.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Ghent University, Belgium .
    Dynamic characteristics of compliant journal bearings considering thermal effects2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 94, p. 288-305Article in journal (Refereed)
    Abstract [en]

    A numerical THD model that takes into account mechanical and thermal deformations of a compliant lining is used to investigate the influence of compliance on dynamic characteristics of a two axial groove bearing. A detailed study on the contribution of mechanical and thermal deformation components of the compliant lining to the non-dimensional bearing stiffness and damping is carried out. Thermal deformation is found to increase horizontal stiffness K<inf>yy</inf> and cross-coupled stiffness K<inf>xy</inf> and slightly reduce journal critical mass. Mechanical deformation of the compliant lining is found to decrease damping, reduce vertical and cross-coupled K<inf>xy</inf> stiffness. Radial clearance is found to increase stiffness, except its horizontal component, and decrease horizontal damping. Compliant lining is found to improve bearing stability.

  • 71.
    Kuznetsov, Evgeny
    et al.
    Lulea Univ Technol, Div Machine Elements.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Stability analysis of a compliant lemon bore journal bearing2008In: Proceedings of the 9th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA 2008: July 7-9, 2008, Haifa, Israel, American Society of Mechanical Engineers , 2008, Vol. 3, p. 561-568Conference paper (Refereed)
    Abstract [en]

    Dynamic coefficients for a lemon bore journal bearing with a compliant PTFE surface are computed. An efficient method for the calculation of bearing dynamic coefficients proposed by Lund [4] has been extended to compliant bearings. Comparison with a rigid babbitted lemon bore journal bearing in terms of dynamic coefficients and stability is given and discussed. It is shown that it is important to consider perturbations of both the oil film and the compliant lining to obtain realistic results. It is also shown that stability of compliant bearings is improved at some eccentricities compared with conventional babbitted bearings.

  • 72.
    Kuznetsov, Evgeny
    et al.
    Division of Machine Elements, Luleå University of Technology.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Fillon, Michel
    THD analysis of a compliant journal bearing considering liner deformation2009In: Proceedings of the World Tribology Congress 2009: Sunday 6th to Friday 11th, September, 2009, Kyoto, Japan, 2009, Vol. 216, p. 216-Conference paper (Refereed)
    Abstract [en]

    The effect of compliant PTFE lining on hydrodynamics was studied. Results for the white metal and PTFE lined bearings were compared in terms of the maximum temperature, oil film thickness, and power loss. The oil film thickness in the PTFE bearing was shown. A favorable oil pocket was formed in the loaded zone. Temperature in the PTFE bearing was slightly higher. 

  • 73. Kuznetsov, Evgeny
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Fillon, Michel
    THD analysis of compliant journal bearings considering liner deformation2011In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 44, no 12, p. 1629-1641Article in journal (Refereed)
    Abstract [en]

    A numerical THD model is developed to investigate the effect of lining compliance on the bearing characteristics. The analysis shows increased load carrying capacity, significantly reduced peak pressures and thicker oil film in the loaded zone compared to a white metal bearing. Slightly thinner oil films are predicted at the bearing edges. Temperature and power loss are found to be similar for some load–speed combinations but higher for other operating conditions. It is also shown that load carrying capacity is more sensitive to thermal expansion while pressure and oil film thickness profiles are more sensitive to elastic deformation.

  • 74. McCarthy, D. M. C.
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Sherrington, I.
    Oil-film thickness and temperature measurements in PTFE and babbitt faced tilting-pad thrust bearings2005In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 219, no 3, p. 179-185Article in journal (Refereed)
    Abstract [en]

    The influence of pad facing material on hydrodynamic lubrication in tilting-pad thrust bearings is investigated in terms of pad and oil-film temperatures and thicknesses. Two tilting-pad thrust bearings are examined: one with babbitt pad facing, the other with a layer of PTFE-based composite material. Frictional torque, pad, collar, and oil-film temperatures and thicknesses are all monitored by means of a comprehensive array of sensors mounted in the bearing and shaft.A considerably smaller range of temperature is seen in the steel backing immediately below the surface material for the PTFE faced pads. Oil-film temperatures measured at the mid-point on the pad trailing edge show no significant difference between the two bearings. Oil-film thicknesses in the two bearings are seen to differ. At the leading edge, oil-film thickness is thinner for the PTFE pad than for babbitt. However, at the trailing edge the PTFE pad has the thicker film.

  • 75. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Assessment of polymer composites for hydrodynamic journal bearing applications2008Conference paper (Other academic)
    Abstract [en]

    Polymer composites are employed as facing materials in hydrodynamic bearings for their low friction and "compliant" properties which play an important role during machinery operation. In journal bearings, this low friction property can be of significant importance during start and stop cycles when insufficient oil is available to fully separate the surfaces in relative motion. Current work is aimed at determining a suitable material for use in hydrodynamic journal bearings. This study investigates friction and wear encountered during the transition from the stationary state to operational speed (acceleration) during initial start-up. This is examined for virgin PTFE together with a series of commercially available PTFE-based composites and a babbitt material in boundary / mixed lubrication conditions. Tests are performed using a standard laboratory block-on-ring test apparatus with a VG32 mineral oil.

  • 76. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Assessment of polymer composites for hydrodynamic journal-bearing applications2009In: Lubrication Science, ISSN 0954-0075, Vol. 21, no 8, p. 331-341Article in journal (Refereed)
    Abstract [en]

    Polymer composites are used as facing materials in hydrodynamic bearings for their low friction and compliant properties, which play an important role during machinery operation. In journal bearings, this low friction property can be of significant importance during start and stop cycles when insufficient oil is available to fully separate the surfaces in relative motion. Current work is aimed at determining a suitable material for use in hydrodynamic journal bearings for applications in hydroelectric power plants. This study investigates friction and wear encountered during the transition from the stationary state to operational speed (acceleration) during initial start-up. This is examined for virgin poly-tetra-fluoro-ethylene (PTFE) together with a series of commercially available PTFE-based composites and a babbitt material in boundary/mixed lubrication conditions. Tests are performed using standard laboratory block-on-ring test apparatus with a VG32 mineral oil.

  • 77. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    "Break-away" friction for PTFE-based composites2008In: Technische Akademie Esslingen International Tribology Colloquium Proceedings / [ed] Wilfried J. Bartz, 2008Conference paper (Refereed)
    Abstract [en]

    The use of polymer composites as facing materials in hydrodynamic thrust bearings gives performance benefits in terms of temperature distribution and friction losses. A study was carried out to investigate the break-away friction encountered during the transition phase (acceleration) under initial start-up from stationary state to full operational speed. This was examined for a series of commercially available PTFE-based composites. The lubricant used was a mineral oil. Best performance in terms of relative friction and wear was found for a carbon filled PTFE composite material. This is an abstract of a paper presented at the 16th International Colloquium Tribology Lubricants Materials and Lubrication Engineering (Stuttgart/Ostfildern, Germany 1/15-17/2008).

  • 78. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Byheden, A.
    Hydrodynamic journal bearing performance using rapeseed base fluid lubricant2008In: Lubricants, materials and lubrication engineering: 16th International Colloquium Tribology; January 15 - 17, 2008 in Stuttgart/Ostfildern, Germany, 2008Conference paper (Refereed)
    Abstract [en]

    The use of Environmentally Adapted Lubricants (EAL) is a subject of growing interest as public environmental awareness and new legislation increasingly demands the replacement of mineral oil lubricants. Vegetable-based fluids are widely seen as providing lubricants from a renewable source as well as meeting demands for improved biodegradability. A study was carried out to extend the available knowledge in respect to the use of vegetable base fluids in hydrodynamic lubrication. The influence of viscosity index (VI) on bearing performance was also examined. Three mineral turbine oils were used. Good comparability between the rapeseed fluid and the two thinner mineral oils was observed. This is an abstract of a paper presented at the 16th International Colloquium Tribology Lubricants Materials and Lubrication Engineering (Stuttgart/Ostfildern, Germany 1/15-17/2008).

  • 79. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Byheden, Åke
    Influence of oil type on the performance characteristics of a two axial groove journal bearing2008In: Proceedings of NORDTRIB 2008, 13th Nordic Symposium on Tribology: Scandic Rosendahl Hotel, Tampere, Finland, June 10 - 13, 2008, 2008Conference paper (Refereed)
    Abstract [en]

    The use of Environmentally Adapted Lubricants (EALs) is a subject of growing interest to industry as legislation increasingly demands the replacement of mineral oil lubricants. Vegetable based fluids are widely seen as providing lubricants from a renewable source as well as meeting demands for improved biodegradability. However, at present, utilisation of such fluids is limited due to their rapid oxidation. EALs produced from other base stocks (i.e. synthetic esters) have been shown to provide performance benefits in hydrodynamic thrust bearings. In the present study, a hydrodynamic journal bearing test rig has been employed to compare the performance of three EALs (a VG32 saturated ester, rapeseed base fluid and a Propylene Glycol Dioleate) relative to three mineral turbine oils (ISOVG32, ISOVG46 and ISOVG68) in the hydrodynamic regime. Results are given in terms of temperature, power loss and minimum film thickness. The impact of oil VI is also discussed.

  • 80. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Byheden, Åke
    Influence of oil type on the performance characteristics of a two-axial groove journal bearing2009In: Lubrication Science, ISSN 0954-0075, Vol. 21, no 9, p. 366-377Article in journal (Refereed)
    Abstract [en]

    The use of environmentally adapted lubricants (EALs) is a subject of growing interest to industry as legislation increasingly demands the replacement of mineral oil lubricants. Vegetable-based fluids are widely seen as providing lubricants from a renewable source, as well as meeting demands for improved biodegradability. However, at present, utilization of such fluids is limited due to their rapid oxidation. EALs produced from other base stocks (i.e. synthetic esters) have been shown to provide performance benefi ts in hydrodynamic thrust bearings. In the present study, a hydrodynamic journal bearing test rig has been employed to compare the performance of three EALs (a VG32 saturated ester, rapeseed base fluid and a propylene glycoldioleate) relative to three mineral turbine oils (ISOVG32, ISOVG46 and ISOVG68) in the hydrodynamic regime. Results are given in terms of temperature, power loss and minimum fi lm thickness. The impact of oil viscosity index is also discussed.

  • 81. Mccarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Kassfeldt, Elisabet
    Pach, Mayte
    Byheden, Åke
    Norrby, Thomas
    Aged environmentally adapted lubricants Part II: Performance evaluation in boundary lubricated contacts2006In: Automotive and industrial lubrication: International Colloquium Tribology, 2006, Vol. 140-, p. 140-Conference paper (Refereed)
    Abstract [en]

    Experiments are conducted to compare the performance of fresh and aged samples of three oils in a boundary lubricated contact. These oils are Oil A (a commercially available unsaturated synthetic ester based hydraulic fluid (ISOVG32)), Oil B (a mineral based turbine oil (ISOVG68), and Oil C (a saturated synthetic ester based lubricating fluid (ISOVG46)). Tests are performed using a tin-bronze on steel contact in a pin-on-disc apparatus. Results from these tests provide data relating to friction and wear and their coupling to the aging of the fluids. No evidence of any significant deterioration of lubricant performance is observed for any of the fluids tested. 

  • 82. McCarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Pach, M.
    Dmitriev, A.
    Performance evaluation for aged environmentally adapted lubricants in bronze-steel sliding contacts2008In: Journal of Synthetic Lubrication, ISSN 0265-6582, Vol. 25, no 3, p. 115-129Article in journal (Refereed)
    Abstract [en]

    Environmentally adapted lubricants (EALs) are becoming of increasing interest to the industry as legislation demands the replacement of mineral oil lubricants. However, little or nothing is known about the infl uence of ageing on the performance of these fluids in mixed and boundary lubricated tribological contacts. In this study, samples of three fully formulated lubricating oils, both in their 'unaged' form and 'aged' by means of an oxidation process in the laboratory, were utilized in a detailed study whereby variations in relative lubrication performance were examined. Standard laboratory pin-on-disc equipment was utilized in order to allow comparisons to be made and the definition of conclusions for a sliding tin bronze on steel contact. This simulated the interaction between an oil-lubricated bronze bushing and steel shaft as found in the vane adjustment mechanism of a Kaplan turbine. X-ray photoelectron spectroscopy analysis was employed to assess the effect on surface layer structural chemistry. Results showed, for the specific application being investigated, that EALs continue to function well in terms of their friction and wear performance even at high acid numbers.

  • 83. Mccarthy, Donald
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Sherrington, Ian
    Oil film thickness and temperature measurements in PTFE and Babbitt faced tilting-pad thrust bearings2006In: Proceedings of the 11th Nordic symposium on tribology: NORDTRIB 2004, 2006, Vol. 167-176, p. 167-176Conference paper (Refereed)
    Abstract [en]

    The influence of pad facing material on hydrodynamic lubrication in tilting-pad thrust bearings is investigated in terms of pad and oil-film temperatures and thicknesses. Two tilting-pad thrust bearings are examined: one with babbitt pad facing, the other with a layer of PTFE-based composite material. Frictional torque, pad, collar, and oil-film temperatures and thicknesses are all monitored by means of a comprehensive array of sensors mounted in the bearing and shaft. A considerably smaller range of temperature is seen in the steel backing immediately below the surface material for the PTFE faced pads. Oil-film temperatures measured at the mid-point on the pad trailing edge show no significant difference between the two bearings. Oil-film thicknesses in the two bearings are seen to differ. At the leading edge, oil-film thickness is thinner for the PTFE pad than for babbitt. However, at the trailing edge the PTFE pad has the thicker film.

  • 84. Mill, O.
    et al.
    Dahlbäck, N.
    Worman, A.
    Knutsson, Sven
    Johansson, F.
    Andreasson, Patrik
    Yang, J.
    Lundin, U.
    Aidanpää, Jan-Olov
    Nilsson, H.
    Cervantes, Michel
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Analysis and development of hydro power research synthesis within Swedish Hydro Power Centre2010Report (Other academic)
    Abstract [en]

    The market for hydropower re-investments in Sweden is approx 2.5 billion SEK/yr the coming decade. Large investments will also be carried out in Swedish tailing dams. This will result in challenging projects and need of experts. A crucial factor for a successful management of these challenges is the supply of engineers and researchers with hydro power and dam skills and knowledge. Swedish Hydro Power Centre (Svenskt vattenkraftcentrum, SVC) is a competence centre for university education and research environments within hydro power and mining dams. SVC comprises of two knowledge areas: Hydraulic Engineering and Hydro Turbines and Generators, respectively. SVC builds high-quality and long term sustainable knowledge at selected universities.

  • 85. Norrby, T.
    et al.
    Torbacke, M.
    Byheden, Å.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    EALs for hydropower applications: Part 2 turbine oil development and field testing2006In: Automotive and industrial lubrication: 15th International Colloquium Tribology, 2006, Vol. 144-, p. 144-Conference paper (Refereed)
    Abstract [en]

    Research regarding environmentally adapted lubricants results of the research performed at LuleÃ¥ University of Technology were positive. Thus, the formulation work of an environmentally adapted lubricant for hydropower applications started. A change to a synthetic ester based lubricant would give technical advantages as well as environmental benefits. The initial tests were conducted on the base fluid. Two turbine oils were developed, Turb Way SE and TurbWay SE LV, for hydropower applications. Oxidation tests were performed in both the RPVOT (ASTM D 2272) and in TOST (ASTM D 943). The stability of the turbine oil was > 20 times better than tested environmentally adapted hydraulic fluids. Field tests were conducted in a full scale turbine at Porjus hydropower plant to confirm the promising results obtained from the research in the tilting thrust bearing rig. 

  • 86. Pach, Mayte
    et al.
    Byheden, Åke
    Norrby, Thomas
    Mccarthy, Donald
    Kassfeldt, Elisabet
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Aged environmentally adapted lubricants Part I: Techniques and procedures for accelerated ageing2006In: Automotive and industrial lubrication: International Colloquium Tribology / [ed] Wilfried J. Bartz, 2006, Vol. 139, p. 139-Conference paper (Refereed)
    Abstract [en]

    The aging behavior of synthetic lubricants, in particular environmentally adapted lubricants esters, in comparison to mineral base oils, is studied. V Three fully commercially formulated lubricants were subjected to an oxidation process using a modified dry-Waterless Turbine Oil Oxidation Stability Test. The oils were: Oil A (hydraulic unsaturated ester with antioxidants and corrosion inhibitors), Oil B (turbine mineral oil with antioxidants and corrosion inhibitors), and Oil C (turbine saturated ester oil with antioxidants and corrosion inhibitors). 

  • 87.
    Pilkington, Georgia A.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Harris, Kathryn
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Bergendal, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Reddy, Akepati Bhaskar
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Pålsson, G. K.
    Vorobiev, A.
    Antzutkin, O. N.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Ghent University, Belgium.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden.
    Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance2018In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 148, no 19, article id 193806Article in journal (Refereed)
    Abstract [en]

    Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential.

  • 88.
    Ploss, Moritz A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Influence of electric potential on the apparent viscosity of an ionic liquid: facts and artifacts2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 38, p. 26609-26615Article in journal (Refereed)
    Abstract [en]

    According to recent findings, the steady shear viscosity of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([Emim][Tf2N]) decreases significantly under the influence of electric potential. This implies a causal connection between nanoscale ordering at the electrified interface and a macroscopic change of transport properties. To study this phenomenon in more detail, we reproduced the above-mentioned measurements; however, we find no evidence that the viscosity of [Emim][Tf2N] is a function of electric potential. Additionally, our results show that steady shear measurements can lead to artifacts that, at first glance, may appear to be potential-induced changes in viscosity. We demonstrate that the artifacts result from a sliding electrical contact at the working electrode of the electrochemical cell and we suggest to consider our findings for future viscosity measurements of ionic liquids.

  • 89.
    Ploss, Moritz
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Tian, Yiyuan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Yoshikawa, Sosaku
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Univ Tokyo, Dept Mech Engn, Tokyo 1138656, Japan.
    Westbroek, Rene
    Axel Christiernsson Int AB, S-44911 Nol, Sweden..
    Leckner, Johan
    Axel Christiernsson Int AB, S-44911 Nol, Sweden..
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Tribological Performance of Non-halogenated Phosphonium Ionic Liquids as Additives to Polypropylene and Lithium-Complex Greases2020In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 68, no 1, article id 3Article in journal (Refereed)
    Abstract [en]

    Four non-halogenated ionic liquids (ILs) with trihexyl(tetradecyl)phosphonium cation are tested as lubricant additives to polypropylene (PP) and lithium-complex (LiX) greases. In pin-on-disk tests at elevated temperatures, the addition of an IL with bis(oxalato)borate ([BOB]) anion reduces wear by up to 50% when compared to the neat LiX base grease; an IL with bis(mandelato)borate ([BMB]) anion reduces friction by up to 60% for both PP and LiX. Elemental analysis reveals that oxygen-rich tribofilms help to reduce wear in case of [BOB], while the friction reduction observed for [BMB] is likely caused by adsorption processes. We find that temperature has a pronounced effect on additive expression, yet additive concentration is of minor importance under continuous sliding conditions. In contrast, rolling-sliding experiments at 90 degrees C show that the traction performance of LiX grease is dependent on additive concentration, revealing a reduction in traction by up to 30 and 40% for [BMB]- and [BOB]-containing ILs at concentrations of 10 wt%. Finally, an IL with dicyanamide anion reduces friction and increases wear in pin-on-disk tests at room temperature, while an IL with bis-2,4,4-(trimethylpentyl)phosphinate anion increases wear, showing only limited potential as grease additives. Overall, this work demonstrates the ability of non-halogenated ILs to significantly extend grease performance limits.

  • 90.
    Radiom, Milad
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Pedraz, Patricia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Pilkington, Georgia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Rohlmann, Patrick
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Department of Electrical Energy, Metals, Mechanical Constructions and Systems, Ghent University, B-9052 Ghent, Belgium.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, SE-100 44 Stockholm, Sweden.
    Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid: Effect of Substrate and Temperature2018In: Colloids and Interfaces, ISSN 2504-5377, Vol. 2, no 4, article id 60Article in journal (Refereed)
    Abstract [en]

    We investigate the interfacial properties of the non-halogenated ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in proximity to solid surfaces, by means of surface force measurement. The system consists of sharp atomic force microscopy (AFM) tips interacting with solid surfaces of mica, silica, and gold. We find that the force response has a monotonic form, from which a characteristic steric decay length can be extracted. The decay length is comparable with the size of the ions, suggesting that a layer is formed on the surface, but that it is diffuse. The long alkyl chains of the cation, the large size of the anion, as well as crowding of the cations at the surface of negatively charged mica, are all factors which are likely to oppose the interfacial stratification which has, hitherto, been considered a characteristic of ionic liquids. The variation in the decay length also reveals differences in the layer composition at different surfaces, which can be related to their surface charge. This, in turn, allows the conclusion that silica has a low surface charge in this aprotic ionic liquid. Furthermore, the effect of temperature has been investigated. Elevating the temperature to 40 &deg;C causes negligible changes in the interaction. At 80 &deg;C and 120 &deg;C, we observe a layering artefact which precludes further analysis, and we present the underlying instrumental origin of this rather universal artefact.

  • 91.
    Rohlmann, Patrick
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Munavirov, Bulat
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Antzutkin, Oleg
    Lulea Univ Technol, Chem Interfaces, Lulea, Sweden..
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Surfaces Proc & Formulat, Stockholm, Sweden.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Univ Ghent, Dept Elect Energy Met Mech Construct & Syst, Ghent, Belgium.
    Non-halogenated Ionic Liquid Dramatically Enhances Tribological Performance of Biodegradable Oils2019In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 7, article id 98Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that a phosphonium orthoborate ionic liquid may serve as a wear reducing additive in biodegradable oils at steel-steel surfaces in the boundary lubrication regime. Tribological tests were performed in a bail-on-three plate configuration. A set of surface characterization techniques-SEM/EDS, FIB and white light interferometry were used to characterize surfaces following the tribotests and to observe the formation of any tribofilms. B-11 NMR was used to follow changes in the composition of the ionic-liquid-oil blends and to identify boron-containing decomposition products after the tribotests. The ionic liquid reduces the wear of steel surfaces by up to 92% compared to the neat oil at 90 degrees C; it is shown that the reduction in wear can be correlated with the formation of boron enriched patches in the boundary films.

  • 92.
    Rutland, Mark W.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Notley, Shannon
    Traction Drive Fluid2015Patent (Other (popular science, discussion, etc.))
  • 93. Sahlin, Fredrik
    et al.
    Almqvist, Andreas
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Larsson, Roland
    A cavitation algorithm for arbitrary lubricant compressibility2005In: Proceedings of the World Tribology Congress III - 2005, 2005, Vol. Paper no 63940, p. 541-542Conference paper (Refereed)
    Abstract [en]

    A general cavitation algorithm is presented that accommodates for an arbitrary density-pressure relation. Here it is possible to model the compressibility of the lubricant in such way the density-pressure relation is realistic from sub-cavity to high pressure regions respectively. The algorithm preserves mass continuity which is of importance when inter-asperity cavitation of rough surfaces is considered. Results with this algorithm for different density-pressure relations are presented and discussed.

  • 94. Sahlin, Fredrik
    et al.
    Almqvist, Andreas
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Larsson, Roland
    Rough surface flow factors in full film lubrication based on a homogenization technique2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 7, p. 1025-1034Article in journal (Refereed)
    Abstract [en]

    This paper describes a method to compute the flow factors that compensate for an arbitrary surface roughness in a compressible hydrodynamic lubrication based on a homogenization technique. The Reynolds equation is used as the governing equation and the two-scale expansion involved in the homogenization process enables the local roughness scale to be treated separately from the global geometry scale. With this method, it is possible to compute the flow factors for any deterministic roughness. Measured two-dimensional surface profiles are used as examples. Profiles having the same Abbot curve are also shown to have the same flow factors, providing an efficient classification of surfaces in hydrodynamic two-dimensional contacts. Flow factors are computed for the rough surface profiles, and solutions for global bearing geometry are obtained and compared with the corresponding solutions from a smooth geometry.

  • 95. Sahlin, Fredrik
    et al.
    Almqvist, Andreas
    Larsson, Roland
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    A cavitation algorithm for arbitrary lubricant compressibility2007In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 40, no 8, p. 1294-1300Article in journal (Refereed)
    Abstract [en]

    A general cavitation algorithm that accommodates for an arbitrary density-pressure relation is presented. It is now possible to model the compressibility of the lubricant in such a way that the density-pressure relation is realistic throughout the contact. The algorithm preserves mass continuity for cavitation caused by bearing geometry and surface topography. It is a commonly accepted physical assumption that the contribution of the pressure driven flow is negligible in the cavitated region. This phenomenon is adopted in the present algorithm, which is similar to that of Elrod, and is modeled by a switch function that terminates the pressure gradient at the cavitation regions. Results with this algorithm for different density-pressure relations are presented and discussed. The effects of inlet conditions, such as surface roughness and starvation, on the load carrying capacity of the contact are analyzed.

  • 96. Sahlin, Fredrik
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Almqvist, Torbjorn
    Larsson, Roland
    Two-Dimensional CFD-Analysis of Micro-Patterned Surfaces in Hydrodynamic Lubrication2005In: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 127, no 1, p. 96-102Article in journal (Refereed)
    Abstract [en]

    Results of a numerical study of the influence of micro-patterned surfaces in hydrodynamic lubrication of two parallel walls are reported. Two types of parameterized grooves with the same order of depth as the film thickness are used on one stationary wall. The other wall is smooth and is sliding with a specified tangential velocity Isothermal incompressible two dimensional full film fluid flow mechanics is solved using a Computational Fluid Dynamics method. It is shown that, by introducing a micro-pattern on one of two parallel walls, a net pressure rise in the fluid domain is achieved. This produces a load carrying capacity on the walls which is mainly contributed by fluid inertia. The load carrying capacity increases with Reynolds number The load carrying capacity is reported to increase with groove width and depth. However at a certain depth a vortex appears in the groove and near this value the maximum load carrying capacity is achieved. It is shown that the friction force decreases with deeper and wider grooves. Among all geometries studied, optimum geometry shapes in terms of hydrodynamic performance are reported.

  • 97. Sahlin, Fredrik
    et al.
    Glavatskih, Sergei
    Luleå University of Technology, Division of Machine Elements.
    Almqvist, Torbjörn
    Larsson, Roland
    2D CFD-analysis of micro-patterned surfaces in hydrodynamic lubrication2004In: Proceedings of the ASME/STLE international joint tribology conference: IJTC 2004, 2004, Vol. Paper no 64009, p. 1637-1645Conference paper (Refereed)
    Abstract [en]

    Results of a numerical study of the influence of micro-patterned surfaces in hydrodynamic lubrication of two parallel walls are reported. Two types of parameterized grooves with the same order of depth as the film thickness are used on one stationary wall. The other wall is smooth and is sliding with a specified tangential velocity. Isothermal incompressible two dimensional full film fluid flow mechanics is solved using a Computational Fluid Dynamics method. It is shown that, by introducing a micro-pattern on one of two parallel walls, a net pressure rise in the fluid domain is achieved. This produces a load carrying capacity on the walls which is mainly contributed by fluid inertia. The load carrying capacity increases with Reynolds number. The load carrying capacity is reported to increase with groove width and depth. However, at a certain depth a vortex appears in the groove and near this value the maximum load carrying capacity is achieved. It is shown that the friction force decreases with deeper and wider grooves. Among all geometries studied, optimum geometry shapes in terms of hydrodynamic performance are reported.

  • 98.
    Sarman, Sten
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden..
    Wang, Yong-Lei
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.;Stanford Univ, Dept Chem, Stanford, CA 94305 USA..
    Rohlmann, Patrick
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Laaksonen, Aatto
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.;Uppsala Univ, Dept Chem, Angstrom Lab, Box 538, S-75121 Uppsala, Sweden..
    Rheology of phosphonium ionic liquids: a molecular dynamics and experimental study2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 15, p. 10193-10203Article in journal (Refereed)
    Abstract [en]

    We have studied the rheological behavior of the ionic liquid trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P-66614][BMB], and compared it with that of another ionic liquid, namely trihexyl(tetradecyl)phosphonium chloride, [P-66614][Cl]. The non-halogenated [P-66614][BMB] has been selected as it is known to provide enhanced lubrication performance and is, consequently, of technological importance. The ionic liquid [P-66614][Cl], despite its relatively simple anion, exhibits viscosities very similar to those of [P-66614][BMB], making it an excellent reference fluid for the modeling study. The viscosities of the ionic liquids have been obtained by equilibrium atomistic simulations using the Green-Kubo relation, and by performing nonequilibrium shear flow simulations. The influence of the simulation system size and a reduction of the atomic charges on the viscosities of the ionic liquids are systematically studied. The atomic charges are reduced to mimic the temperature dependent charge transfer and polarization effects. It has been found that scaling the point charges with factors between 0.60 and 0.80 from full ion charges can provide reliable viscosities of [P-66614][BMB], consistent with the experimentally measured viscosities within the studied temperature interval from 373 to 463 K. The viscosities of [P-66614][Cl] have been obtained with scaling factors between 0.80 and 1.0 reflecting the lower polarizability and charge transfer effects of the chloride anion.

  • 99. Shah, F. U.
    et al.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Antzutkin, O. N.
    Novel alkylborate-dithiocarbamate lubricant additives: Synthesis and tribophysical characterization2012In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 45, no 1, p. 67-78Article in journal (Refereed)
    Abstract [en]

    Boron-based lubricant additives have recently received significant attention, because of their wear-reducing and frictional properties and low pollution. At the same time, dithiocarbamate complexes with different metals have a long history of being used as multifunctional additives to lubricants. In this study, novel, environmentally friendly additives containing alkylborate and dithiocarbamate groups with alkyl or methylbenzyl substitutes in one molecule were studied. Tribological tests were performed with the additives admixed in a mineral oil using steel-on-steel contacts in a four-ball tribometer. Borate derivatives of different dithiocarbamate ligands were synthesized by several step reactions to investigate tribochemical properties of boron, sulfur, and nitrogen combined in one selected compound. Viscous liquid products were characterized by multinuclear 1H, 13C, and 11B NMR spectroscopy. The surface morphology and the elemental composition of the tribofilms were investigated using an optical profiler and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). It was found that some of these novel compounds provide better antiwear performance and similar frictional properties compared with a commercially available ZnDTP package. Traces of sulfur in the tribofilms formed with both 0.2 and 1.0 wt% of alkylborate-dithiocarbamate compounds in a mineral oil were detected with EDS. 

  • 100. Shah, F. U.
    et al.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Dean, P. M.
    MacFarlane, D. R.
    Forsyth, M
    Antzutkin, O. N.
    Halogen-free chelated orthoborate ionic liquids and organic ionic plastic crystals2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 14, p. 6928-6938Article in journal (Refereed)
    Abstract [en]

    Five halogen-free orthoborate salts comprised of three different cations (cholinium, pyrrolidinium and imidazolium) and two orthoborate anions, bis(mandelato) borate and bis(salicylato) borate, were synthesised and characterised by DSC, X-ray diffraction and NMR. DSC measurements revealed that glass transition points of these orthoborate salts are in the temperature range from -18 to -2 degrees C. In addition, it was found that [EMPy][BScB] and [EMIm][BScB] salts have solid-solid phase transitions below their melting points, i.e. they exhibit typical features of plastic crystals. Salts of the bis(salicylato) borate anion [BScB](-) have higher melting points compared with corresponding salts of the bis(mandelato) borate anion [BMB](-). Single crystal X-ray diffraction crystallography (for [Chol][BScB] crystals) and solid-state multinuclear (C-13, B-11 and N-15) NMR spectroscopy were employed for the structural characterisation of [Chol][BScB], [EMPy][BScB] and [EMIm][BScB], which are solids at room temperature: a strong interaction between [BScB](-) anions and [Chol](+) cations was identified as (i) hydrogen bonding between OH of [Chol](+) and carbonyl groups of [BScB](-) and (ii) as the inductive C-H center dot center dot center dot pi interaction. In the other salt, [EMIm][BScB], anions exhibit pi center dot center dot center dot pi stacking in combination with C-H center dot center dot center dot pi interactions with [EMIm]+ cations. These interactions were not identified in [EMPy] [BScB] probably because of the lack of aromaticity in cations of the latter system. Our data on the formation of a lanthanum complex with bis(salicylato) borate in the liquid mixture of La3+(aq) with [Chol][BScB] suggest that this class of novel ILs can be potentially used in the extraction processes of metal ions of rare earth elements.

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