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Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,Kujawy Pomorze University | Kaldonski T.J.,Military University of Technology | Macko M.,Kazimierz Wielki University in Bydgoszcz | Urbaniak W.,Kazimierz Wielki University in Bydgoszcz
Archives of Civil and Mechanical Engineering | Year: 2017

We investigate the frictional performance of the hexagonal boron (h-BN) nitride, sintered into the porous iron bearing, with the lubricating hydrocarbon and formulated oils. It was established that the h-BN particles largely improved the tribological performance of the surfaces under contact between the porous bearing and a grey cast iron disc. The h-BN particles (platelets) released during wear reduces friction in a surfactant-free (no additive) lubrication. The hexagonal h-BN solid particles are able to form efficient friction-reducing lamellar sheets on the contacting surfaces. It was found that solubilization of h-BN particles by reverse micelles were not beneficial in reducing friction in lubrication with surfactant. The role played by the surfactant and its effect on h-BN particles lubrication were discussed with respect to reverse micelle and solubilization concepts. © 2017 Politechnika Wrocławska


Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of Economics | Figaszewski Z.A.,University of Bialystok | Figaszewski Z.A.,University of Warsaw | And 3 more authors.
Tribology International | Year: 2010

In this study, the influence of pH on interfacial energy distributed over the phospholipids-bilayer surface model and the effect of hydrophobicity on coefficient of friction (f) were investigated by using microelectrophoresis. An important clinical implication of deficiency in hydrophobicity is the loss of phospholipids that is readily observed in osteoarthritis joints. This paper establishes the influence of pH on interfacial energy upon an increase f, which might be associated with a decrease of hydrophobicity of the articular surface. © 2010 Elsevier Ltd. All rights reserved.


Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of economics | Petelska A.D.,University of Bialystok | Urbaniak W.,Kazimierz Wielki University in Bydgoszcz | And 2 more authors.
Cell Biochemistry and Biophysics | Year: 2013

The wettability of the articular surface of cartilage depends on the condition of its surface active phospholipid overlay, which is structured as multi-bilayer. Based on a hypothesis that the surface of cartilage facilitates the almost frictionless lubrication of the joint, we examined the characteristics of this membrane surface entity in both its normal and degenerated conditions using a combination of atomic force microscopy, contact angle measurement, and friction test methods. The observations have led to the conclusions that (1) the acid-base equilibrium condition influences the lubrication effectiveness of the surface of cartilage and (2) the friction coefficient is significantly dependent on the hydrophobicity of the surface of the tissue, thereby confirming the hypothesis tested in this paper. Both wettability angle and interfacial energy were obtained for varying conditions of the cartilage surface both in its wet, dry and lipid-depleted conditions. The interfacial energy also increased with mole fraction of the lipid species reaching an asymptotic value after 0. 6. Also, the friction coefficient was found to decrease to an asymptotic level as the wettability angle increased. The result reveal that the interfacial energy increased with pH till pH = 4. 0, and then decreased from pH = 4. 0 to reach equilibrium at pH = 7. 0. © 2012 The Author(s).


Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of economics | Urbaniak W.,University of economics | Kaldonski T.,Military University of Technology | Styp-Rekowski M.,University of Natural science
Ecological Engineering | Year: 2010

This study concentrates on the investigation of energy and environmental benefits for used oil pertaining to its reuse through: (i) recovering the heating value of used oils in a combustion process and (ii) re-refining of used oil to produce fresh lube oil products. Tests were made with the used oil samples by ICP technique and the results were compared with standard requirements. We have found that the problems could successfully be solved through used oil management practices including collection centers, transporters, and processors by providing encouragement and financial support towards the re-refining industry. The novelty and value of our work lies in the conclusion that reformulation of motor oil results in lower levels of hazardous elements in used oils. © 2010 Elsevier B.V.


Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of economics | Kaldonski T.,Military University of Technology | Urbaniak W.,University of economics
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology | Year: 2010

An attempt has been made to learn howa two-phase fluid used as a lubricant of porous bearings could improve their load-carrying capacity.Two sets of bearingswere chosen for friction and loading experiments. The first one comprised a self-lubricating porous bearing impregnated with oil and the two-phase fluid, and in the other the two-phase fluid was externally delivered to the bearings. The results showed that the two-phase fluid had a better friction-reducing capacity and a higher load-carrying performance than ordinary porous bearings impregnated with the oil. It is demonstrated that the novel model of the bearings (the so-called second-generation bearings) with the two-phase fluid ensures a fairly efficient lubrication under low friction and high load-carrying capacity. A novel lubrication mechanism, involving a lamellar particulate phase in blocking and unblocking the pores during contact load, has been suggested. © Author 2010.


Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of economics | Urbaniak W.,University of economics | Urbaniak W.,Kazimierz Wielki University in Bydgoszcz | Oloyede A.,Queensland University of Technology
Wear | Year: 2011

In this study, the influence of surface wettability (θ) and interfacial energy (γ) on the coefficient of friction (f) of tribopair surfaces in aqueous environment was investigated using a tribotester. The wettability behaviour of various tribopair surfaces [hydrophilic (HL) and hydrophobic (HB)]: (HL-HL), (HB-HB) and (HB-HL) was characterized by friction properties in water and aqueous two-phase lubricants (water+additive). The results show that the level of wettability of the tribopairs [the so-called delta wettability, Δθ=(θDisc-θPin)] is related to friction coefficient (f) in aqueous environment. In view of recent results, we conclude that both the interfacial energy and wettability of tribopair surfaces adequately characterize the lubrication processes. © 2011 Elsevier B.V.


Yusuf K.Q.,Queensland University of Technology | Motta N.,Queensland University of Technology | Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of economics | Oloyede A.,Queensland University of Technology
Connective Tissue Research | Year: 2012

The surface amorphous layer of articular cartilage is of primary importance to its load-bearing and lubrication function. This lipid-filled layer is degraded/disrupted or eliminated when cartilage degenerates due to diseases. This article examines further the characteristic of this surface overlay using a combination of microscopy and imaging methods to evaluate the hypothesis that the surface of articular cartilage can be repaired by exposing degraded cartilage to aqueous synthetic lipid mixtures. The preliminary results demonstrate that it is possible to create a new surface layer of phospholipids on the surface of cartilage following artificial lipid removal, but such a layer does not possess enough mechanical strength for physiological function when created with either unsaturated palmitoyl-oleoyl-phosphatidylcholine or saturated dipalmitoyl-phosphatidylcholine component of joint lipid composition alone. We conclude that this may be due to low structural cohesivity, inadequate time of exposure, and the mix/content of lipid in the incubation environment. Copyright © Informa Healthcare USA, Inc.


Rauckyte T.,University of Technology and Life Sciences in Bydgoszcz | Zak S.,University of Technology and Life Sciences in Bydgoszcz | Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of Economics | Oloyede A.,Queensland University of Technology
Journal of Environmental Engineering and Landscape Management | Year: 2010

This paper describes a case study of petroleum-contaminated soil/sediment samples which were analyzed using gas chromatography-flame ionization detector (GC-FID) for total petroleum hydrocarbons (TPH), volatile aromatic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX) and naphthalene by GC-MS, and oil and grease (O/G) content by sonication in hexane. The ratio of (TPH) / (O/G) shows that the hydrocarbon fraction is between 7% and 87%. The content of volatile organic fraction BTEX accounts for only a small proportion of total TPH, and the ratio of (BTEX) / (TPH) ranges from 0.1% to 0.6%. It should be stressed that the use of TPH methods as against gas chromatography must be done with care because the potential risk posed by BTEX compounds may not be adequately addressed.


Pawlak Z.,Tribochemistry Consulting | Pawlak Z.,University of Bydgoszcz | Urbaniak W.,Kazimierz Wielki University in Bydgoszcz | Urbaniak W.,Technical University | And 2 more authors.
Cell Biochemistry and Biophysics | Year: 2015

The surface of an articular cartilage, coated with phospholipid (PL) bilayers, plays an important role in its lubrication and movement. Intact (normal) and depleted surfaces of the joint were modelled and the pH influence on the surface interfacial energy, wettability and friction were investigated. In the experiments, the deterioration of the PL bilayer was controlled by its wettability and the applied friction. The surrounding fluid of an undamaged articular cartilage, the synovial fluid, has a pH value of approximately 7.4. Buffer solutions were formulated to represent the synovial fluid with various pH values. It was found that the surface interfacial energy was stabilised at its lowest values when the pH varied between 6.5 and 9.5. These results suggested that as the PL bilayers deteriorated, the hydration repulsion mechanism became less effective as friction increased. The decreased number of bilayers changed the wettability and lowered PL lubricant properties. © 2014, Springer Science+Business Media New York.


PubMed | Tribochemistry Consulting, Kazimierz Wielki University in Bydgoszcz, Nicolaus Copernicus University and University of Bydgoszcz
Type: Journal Article | Journal: Cell biochemistry and biophysics | Year: 2016

The surface of an articular cartilage, coated with phospholipid (PL) bilayers, plays an important role in its lubrication and movement. Intact (normal) and depleted surfaces of the joint were modelled and the pH influence on the surface interfacial energy, wettability and friction were investigated. In the experiments, the deterioration of the PL bilayer was controlled by its wettability and the applied friction. The surrounding fluid of an undamaged articular cartilage, the synovial fluid, has a pH value of approximately 7.4. Buffer solutions were formulated to represent the synovial fluid with various pH values. It was found that the surface interfacial energy was stabilised at its lowest values when the pH varied between 6.5 and 9.5. These results suggested that as the PL bilayers deteriorated, the hydration repulsion mechanism became less effective as friction increased. The decreased number of bilayers changed the wettability and lowered PL lubricant properties.

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