Lubrication Science (Lubric Sci)

Publications in this journal

• Article: A method for the identification and quantitation of hydraulic fluid contamination of turbine engine oils by gas chromatography–chemical ionisation mass spectrometry

  Renée L. Webster, David J. Evans, Paul M. Rawson
  Lubrication Science 01/2012;
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  Article: Non‐varnishing and tribological characteristics of polyalkylene glycol‐based synthetic turbine fluid

  Govind Khemchandani
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  ABSTRACT: Varnish build-up in heavy duty gas turbines is a leading cause of costly unplanned shutdowns and resulting lost power generation capacity. The culprit is the conventional petroleum-based turbine oil, which breaks down to form varnish and sludge that cause servo valves to stick. Use of filtration to remove solid degradation by-products addresses a symptom but not the root cause of varnish formation: the petroleum-based turbine oils themselves. For the best protection against varnish-related shutdowns, a switch from petroleum-based turbine oil to non-varnishing polyalkylene glycol (PAG)-based synthetic turbine fluid was undertaken by four power plants in North America. PAG-based synthetic turbine fluid chemistry, its tribological characteristics and successful trials in GE 7FA heavy duty gas turbines (General Electric Company, Fairfield, CT, USA) are discussed in this paper. PAG-based synthetic turbine fluid has outperformed the hydrocarbon turbine oil in reduced sludge and varnish formation due to its polar nature and solvating power in plant trials as well as in a modified ASTM D 2893 test. Copyright © 2011 John Wiley & Sons, Ltd.
  Lubrication Science 12/2011; 24(1):11 - 21.
• Article: Poly‐α‐olefin‐based synthetic lubricants: a short review on various synthetic routes

  Saptarshi Ray, PVC Rao, NV Choudary
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  ABSTRACT: This paper reviews various synthetic protocols for poly-α-olefin (PAO) synthetic lubricant base stocks that have evolved over the years. Apart from conventional Lewis acid catalysts known for the synthesis of poly-α-olefins, such as aluminium trichloride and boron trifluoride, several new catalysts such as metallocenes and ionic liquids have been reported by various researchers. With increasing options of catalytic processes available, it is now possible to produce tailor made PAOs and thus control the properties of the end products, such as viscosity and the viscosity index. Although 1-decene is the most widely used monomer for PAO application, researchers have used a wide range of monomers from 1-hexene to 1-tetradecene and internal olefins in some cases.
  Lubrication Science 09/2011; 24(1):23-44.
• Article: Study of pentaerythritol tetraoleate ester as industrial gear oil

  Ponnekanti Nagendramma
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  ABSTRACT: Attention has been paid to biodegradable lubricating oils in the field of lubricant application because of environmental pollution control measures. In Europe and in some part of Asia, the use of environmentally acceptable lubricant is supported by environmental labels. Synthetic and vegetable oil-based esters offer the best choice in formulating environment-friendly lubricants.Pentaerythritol tetraoleate ester has been synthesised using polyol such as pentaerythritol and oleic acid with indigenous ion exchange resin (Indion-130) catalyst. The product was characterised for its physicochemical properties and was evaluated for lubrication performance. This was then compared with extreme pressure type of industrial gear oil VG-68 (IS 8406:1993). The product was found to have good potential for use as a base stock for formulation as extreme pressure type of industrial gear oil VG-68 (IS 8406:1993). Copyright © 2011 John Wiley & Sons, Ltd.
  Lubrication Science 07/2011; 23(8):355 - 362.
• Article: The impact of biofuels on engine oil performance

  F. Gili, A. Igartua, R. Luther, M. Woydt
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  ABSTRACT: The dilution of biogenic fuels into lubricating engine oils often leads to a shortening of the recommended oil drains (between 30% and 60%) and an increase in wear. The large number of overlapping and influencing factors, of which dilution and polymerization of fuel components in the engine oil are emphasised, makes it difficult to find a uniform solution to prevent failures in the various applications.Insofar single solutions for the different types of biofuels are needed. The contribution of base oil chemistry and additives as well as triboactive materials is featured to deal with the adverse effects of biofuels. In the frame of the European Commission (EC)-funded project ‘cleanengine’, tentative engine oils based on esters with a content of renewables and polyglycols are formulated to increase the lubricant's tolerance in engines fuelled with biofuel-based blends, with the aim of ensuring required lubricating and wear protection performance while keeping oil drain intervals unchanged.The present paper focuses on four-stroke diesel applications, fuelled by biodiesel (fatty acid methyl ester — FAME) as well as by rapeseed oil and Jatropha oil (pure vegetable oils, triglycerides), together with relevant blends of those biofuels and conventional diesel fuel.This paper screens the functional profile (in particular rheological, toxicological, bio-compatibility, tribological and biofuels affinity) of lube families with respect to biofuel contamination. Moreover, this is followed by the contributions of piston ring and liner materials as well as thin film coatings. Copyright © 2011 John Wiley & Sons, Ltd.
  Lubrication Science 05/2011; 23(7):313 - 330.
• Article: Influence of humidity on the tribological performance of unmodified soybean and sunflower oils

  Matthew T. Siniawski, Nader Saniei, Pantcho Stoyanov
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  ABSTRACT: In general, vegetable oils exhibit superior lubrication properties but lack the thermal stability of petroleum base stocks. However, vegetable oils could make an ideal candidate as a base stock for lubrication applications involving high humidity levels, such as marine and offshore applications. This study focuses on the friction and wear rate of unmodified soybean and sunflower oils in comparison with an unformulated mineral oil at various levels of relative humidity, ranging from 10% to 98% RH. It was observed that the vegetable oils retain their friction and wear reducing capabilities much better than the mineral oil at high humidity levels. This was attributed to their inherent ability to react with the metallic contacting surfaces and form multilayers of soap films. Furthermore, the soybean oil provided a superior level of wear resistance when compared with the sunflower oil at extremely high levels of relative humidity due to its lower viscosity and differences in chemical compositions. Copyright © 2011 John Wiley & Sons, Ltd.
  Lubrication Science 04/2011; 23(7):301 - 311.
• Article: Property blending relationships for binary mixtures of mineral oil and elektrionised vegetable oil: viscosity, solvent power, and seal compatibility index

  Michel Roegiers, Boris Zhmud
  Lubrication Science 04/2011; 23(6):263 - 278.
• Article: Synergistic effect of diisopropyl phosphite and over‐based calcium sulphonate additives on tribological properties of AISI 52100 steel/Al2O3 ceramics

  Shuyun Jiang, Hongjun Xie
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  ABSTRACT: The friction-reducing and anti-wear effect of the 500SN base oil containing diisopropyl phosphite (T451) and over-based calcium sulphonate (KT5447) on AISI 52100 steel/Al2O3 ceramic were investigated with a ball-on-disc tribometer at a light load of 200 N and a high load of 400 N. The results indicate that the 500SN base oil containing T451 and KT5447 appears to have a synergistic effect on the pair. For the light load of 200 N, the effective composition is 3 wt% T451 + 2–3 wt% KT5447. For the high load of 400 N, the combination of T451 and KT5447 appears to have a synergistic friction-reducing and anti-wear effect. The scanning electron microscope images show that ploughed grooves, pitting, spalling and corrosion are the dominant wear modes for both 200 and 400 N. However, no evidence for the formation of the expected sulphur-containing or phosphorus-containing chemical compound is found according to X-ray photoelectron spectroscopy analysis of the worn steel ball surface at both loads. Copyright © 2011 John Wiley & Sons, Ltd.
  Lubrication Science 04/2011; 23(6):279 - 291.
• Article: Film‐forming properties of castor oil–polyol ester blends in elastohydrodynamic conditions

  Grigor B. Bantchev, Girma Biresaw
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  ABSTRACT: The viscosity and elastohydrodynamic (EHD) film thickness properties of binary blends of castor oil with polyol esters were determined experimentally. Predicted blend viscosities were calculated from the viscosities of the pure blend components. Measured viscosity values were closer to the values predicted using the Lederer model than the Arrhenius model. EHD film thickness data were mostly in agreement with the predictions of the Hamrock–Dowson model. Observed deviations of EHD film thickness were attributed to boundary film formation and thermal effects. Calculated effective pressure–viscosity coefficients, α, displayed a complex relationship with blend viscosity. At 40°C, the addition of 10% polyol esters resulted in a 12–17% drop in α of castor oil. Higher concentrations of polyol esters resulted in an increase of α. At 70 and 100°C, α displayed an almost linear dependence on blend composition. Copyright © 2011 John Wiley & Sons, Ltd.
  Lubrication Science 03/2011; 23(5):203 - 219.
• Article: A parametric investigation of the friction performance of electroless Ni‐B coatings

  Suman Kalyan Das, Prasanta Sahoo
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  ABSTRACT: Friction performance of electroless Ni-B coatings sliding against steel is experimentally investigated in this paper. Friction performance is measured in terms of coefficient of friction (COF) for varying tribological testing parameters such as load, speed and time. Taguchi-based optimisation of the testing parameters is attempted to find the optimal combination of testing parameters for minimum COF. An analysis of variance reveals that all the testing parameters have significant influence on the friction performance of the coating. Also, the interaction between load and speed is found to affect the friction more compared with the rest of the interactions. The coating characterisation is done with the help of scanning electron microscopy (SEM), energy dispersive X-ray and X-ray diffraction analysis. It is found that the Ni-B coating is amorphous in the as-deposited condition but gradually turns crystalline with heat treatment. The sliding tracks observed with SEM showed that abrasive failure is the predominant wear mechanism. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 12/2010; 23(2):81 - 97.
• Article: Non‐Newtonian transient thermoelastohydrodynamic lubrication analysis of an involute spur gear

  You-Qiang Wang, Xue‐Juan Yi
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  ABSTRACT: The lubrication design of gear is based on the assumption that the lubricant is an ideal Newtonian fluid. In fact, The Ree–Eyring fluid model is more in agreement with the lubricant rheological behaviour under medium or mild duty load. It is necessary for engineering lubrication design to study the non-Newtonian transient thermal elastohydrodynamic lubrication (EHL) of gear. In the paper, a full numerical solution to the non-Newtonian transient thermal EHL of gear is obtained by utilising the multi-grid method, which has strong numerical stability, a quick convergence rate and a high degree of accuracy. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 09/2010; 22(10):465 - 478.
• Article: Recent studies on the application of microfabrication technologies for improving tribological properties

  Miki Nakano, Yasuhisa Ando
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  ABSTRACT: The relationships between nanometer-scale surface textures of periodic asperity arrays and friction force in unlubricated conditions and the relationships between micrometer-scale surface textures of two-tier structures and friction force in mixed lubrication conditions were investigated. The friction force and pull-off force were measured on the asperity array in an unlubricated condition. Each force was proportional to the radius of the curvature of the asperity peak. The pull-off force was determined by the Laplace pressure of the capillary condensed water. The friction force was measured on the micrometer-scale surface textures of a two-tier structure in lubricated conditions. The friction coefficient increased with higher bearing characteristic numbers at the higher B, though the friction coefficient was constant at the lower B. The roughness of the pin surface and the geometry of the two-tier structure affected the friction coefficient at the lower B and higher B, respectively. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 08/2010; 23(3):99 - 117.
• Article: Influence of fatty acid additives on the tribological performance of sunflower oil

  Patrick Baumgart, Gabriele Canzi, Tory Hanashiro, Lambert A. Doezema, Matthew T. Siniawski
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  ABSTRACT: Vegetable oils are potential substitutes for petroleum-based lubricants because they are environmentally friendly, renewable, less toxic and readily biodegradable. The addition of free fatty acids has been shown to increase the lubrication performance of vegetable oils at elevated temperatures. The purpose of this study was to evaluate the relationship between the length of the carbon chain in the fatty acid and its effectiveness as an additive for a range of elevated temperatures. Stearic, arachidic and behenic fatty acid additives were added to commercial sunflower oil. All fatty acid additives were shown to be effective in lowering the wear rate and coefficient of friction in ball-on-disc tribological tests. The overall carbon chain length was not observed to have a consistent influence on the effectiveness of the additive. All additives were less effective at temperatures above 100°C. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 08/2010; 22(9):393 - 403.
• Article: Friction evaluation of lubricated laser‐textured surfaces

  Adrian Predescu, Mircea D. Pascovici, Traian Cicone, Cristian S. Popescu, Constantin Grigoriu, Dumitru Dragulinescu
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  ABSTRACT: Despite a large amount of work dedicated to the study of the effects of textured surfaces in tribological pairs, there is still a need for accurate and convincing experimental results to prove the benefic effects predicted theoretically. This paper presents an original experimental set-up with a partially textured flat pin sliding on a rotating disc in the presence of a thin lubricating film of constant thickness. The texture was composed of a series of parallel grooves cut on the half of the pin front face. The main objective of the reported work was the experimental assessment of hydrodynamic performances (load capacity and friction force) for parallel, partially textured sliders and the comparison with a similar step slider. Preliminary results have clearly put in evidence the collective hydrodynamic effect of partially textured surfaces. The stepped configuration has shown greater load capacity with respect to textured configuration. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 06/2010; 22(10):431 - 442.
• Article: Effect of surface roughness of mechanical seals under blood sealing

  Jun Tomioka, Norifumi Miyanaga
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  ABSTRACT: A miniature mechanical seal with cooling water circulating system has been developed as a shaft seal for rotary blood pumps. The present paper describes the establishment of the experimental methods under blood sealing and the estimation of the effect of the surface roughness on the shaft seal problems, especially in the increase of the friction and the leakage. Micro-leakage rates of the blood and the cooling water were measured by an ion chromatography. In this method, the ion concentration was converted into the leakage rate. The frictional loss torque was measured by a torque meter. Results are provided with three types of surface roughness, Ra = 0.009 µm, Ra = 0.088 µm and Ra = 0.170 µm. It is shown that as the surface roughness increases the leakage decreases while the frictional loss torque increases under blood sealing. The best surface roughness in the torque and the leakage characteristics were different. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 06/2010; 22(10):443 - 452.
• Article: Molecular dynamics simulations of elastohydrodynamic lubrication oil film

  Hitoshi Washizu, Toshihide Ohmori
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  ABSTRACT: This paper reviews recent research in molecular dynamics studies of the traction properties of hydrocarbon fluids under elastohydrodynamic lubrication, focusing on the technical problems that arise on making predictions of the traction properties of an oil film with a submicron thickness at the actual sliding contacts of the machine elements by at a nanoscale molecular simulation. The effect of the oil film thickness and shear rate are examined including the result of a submicron thickness simulation of the oil film using a tera-flops computer. The mechanism of the phase transition of the fluids under high pressure, the boundary slip, and the momentum transfer related to the molecular structure of the fluids are also presented. Copyright © 2010 John Wiley & Sons, Ltd.
  Lubrication Science 06/2010; 22(8):323 - 340.