Proceedings of SerbiaTrib '13

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The tribometer operates in principle of inclinedplane. Contact pair together with system for heatingand probe for temperature measurement is rotatedfrom horizontal to the desired angle α. The rotatedangle of inclined plane is measured with readingprecision of one minute, which for a wide intervalof possible values of the coefficient of rollingfriction causes the measurement error less than 3%.Figure 1 – The balance of rolling body at inclined plateThe authors’ starting point was from theoreticalassumption that the contact between ball and flatsurface in laboratory conditions will be achieved onthe small number of unevenness in a regard anumber of unevenness at higher temperatures.Further, it is assumed that due to thermal expansionof material in the contact zone, will result asincreasing of value e (figure 1). This means that asa consequence we will have an increase of rollingmoment resistance and a parallel increase of thecoefficient of rolling friction. The authors believethat there is some correlation between staticcoefficient of rolling friction and the value ofthermal dilatation of contact pair. If we have inmind the stochastic nature of real contact area andnonlinear temperature field, it is hard totheoretically quantify the influence of temperatureon coefficient of friction. Hence, in order toquantify the influence of various parameters oncoefficient of friction, authors will provide relativeextensive experimental research.3. EXPERIMENTAL TESTSExperimental tests were performed on a specialdesigned and constructed tribometer. The completemeasuring instrument is showed on figure 2. Also,all positions are marked with numbers anddescribed in following text. The tribometer consistsof three bigger parts, as follows:1 – Thermoregulator. The main aim of this part is tovary a temperature (in our case is 200°C). There aretwo small screens; one is showing desiredtemperature and another current temperature.2 – Block with thermocouple. Inside of this block,beside thermocouple, there is a system for heatingand probe for temperature measurement. Also, inthis part of tribometer the contact between objectand block is made.3 – Counterweight. This part enables to makerotating of the block with thermocouple with verygood precision.Figure 2 – Measurement instrumentation(1-Thermoregulator, 2-Counterweight,3-Block with thermocouple)The tests were performed with rolling balls ofdifferent diameters over channels with differentradius bends. Balls weight and balls diameter werein a range from 0.04 to 0.08N and from 2.32 to13mm respectively. Bend radius of the blockcovered a range from 2.5 to 8 mm. Balls and blockwere heated on selected temperatures, 20, 100, 150and 200°C. Chosen material for balls and block wassteel DIN 17230 (100Cr6) with hardness 62-66HRC. Hardness is achieved by quenching andtempering process. Ball roughness is Ra=0.002µm.The roughness of the block channels surface was ina range between: Ra=0.8-1µm. The figure 3 is adiagrammatic representation coefficient of rollingfriction dependence regarding temperature andnormal load.Figure 3 – Coefficient of rolling friction dependenceregarding temperature and normal load398 13 th International Conference on Tribology – Serbiatrib’13
4. DISCUSSIONAccording to the theoretical consideration,physical principle and characteristics of inclinedplane for coefficient of static friction measurementcan be applicable in the conditions with highertemperatures. The measurement error is function ofthe angle α and value of friction coefficient, asfollows:tan(α Δα) tanα 100[%] (7)tan(αawhere are:ε - measurement error andΔα – measurement error of angle.Measured coefficient of friction is in the rangefrom 0.01 to 0.05 and reading precision is oneminute based on computation, the measurementerror is less than 3%. This result is totallyacceptable. The results of experimental tests enableglobal overview of how larger number ofparameters influence on coefficient of rollingfriction. Besides variations of temperature and levelof normal load, variations were made to blockchannel radius (the second contact element).From diagram (figure 3) we can conclude thattemperature, which is selected for contact pairheating and normal load (ball weight) has largeinfluence on changing trend of coefficient of rollingfriction. The bend radius has indirect influence onreal contact surface, meaning that larger radiuscorresponds to 10% of lower values of frictioncoefficient. If we have in mind that increasingradius of block bend increases contact pressure thenit can be concluded that results correspond withliterature. In conjunction with above stated, it canbe concluded that to lower coefficient of frictioncorresponds higher contact pressure.Based on analyses of experimental results,generally it can be stated that contact temperaturehas significant influence on coefficient of rollingfriction. However, level of temperature influenceon coefficient of rolling friction is highly dependentfrom normal load value, especially in an area oflower values of normal load.5. CONCLUSIONThe research in the field of static friction isspread in a number of directions. The topicexplored by authors aimed to draw attention thatresearch in a field of static coefficient of rollingfriction have not been carried out in order toquantify complex influence of normal load, contactsurface and temperature on coefficient of rollingfriction. Through theoretical considerationpresented in this paper, authors hypothesized thatthere is necessary thermal potential in a contactzone for redistribution of contact pressure andincrease of rolling moment resistance attemperatures around 200°C. The instrumentationused for static coefficient of rolling frictionmeasurement in a condition of high temperaturesfunctions as inclined plane and enables satisfactorydetermination results of static coefficient of rollingfriction. In this paper the measurement error is lessthan 3%, for performed program of experimentalresearch, and regarding problems of measurementof very small friction forces this is completelysatisfactory. The measurement results of staticcoefficient of rolling friction for selected materials,in a condition of high temperatures, normal loadand bend radius of contact elements variation,indicate a complex influence of temperature in thetesting conditions.Scientists’ future research in this field should bedirected to experimental tests of different materialsin contact and optimization in order to determineminimal values of static coefficient of friction athigh temperatures.ACKNOWLEDGMENTResearch presented in this paper was supportedby Ministry of Science and TechnologicalDevelopment of Republic of Serbia, GrantTR-35021, Title: Razvoj triboloških mikro/nanodvokomponentnih i hibridnih samopodmazajućihkompozita.REFERENCES[1] P. J. Blau, The significance and use of the frictioncoefficient, Tribology International, Vol. 34, No. 9,pp. 585–591, 2001.[2] B. Ivkovic, M. Djurdjanovic, D. Stamenkovic, TheInfluence of the Contact Surface Roughness on theStatic Friction Coefficient, Tribology in Industry,Vol. 22, No. 3&4, pp. 41-44, 2000.[3] U. Muller, R. Hauert, Investigations of thecoefficient of static friction diamond-like carbonfilms, Surface and Coatings Technology, Vol. 174-175, pp. 421–426, 2003.[4] B. Polyakov, S. Vlassov, L. M. Dorogin, P. Kulis,I. Kink, R. Lohmus, The effect of substrateroughness on the static friction of CuO nanowires,Surface Science, Vol. 606, No. 17-18. pp. 1393-1399, 2012.[5] N. Tayebi, A. A. Polycarpou, Modeling the effect ofskewness and kurtosis on the static frictioncoefficient of rough surfaces, TribologyInternational, Vol. 37, No. 6, pp. 491-505, 2004.[6] B. Bhushan, S. Sundararajan, W.W. Scott, S.Chilamakuri, Stiction analysis of magnetic tapes,IEEE Magnetics Transactions, Vol. 33, No. 5, pp.3211-3213, 1997.13 th International Conference on Tribology – Serbiatrib’13 399
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SerbianTribologySocietyFacultyofEng
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Serbian Tribology SocietyUniversity
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Supported byMinistry of Education,
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PrefaceThe International Conference
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ContentsPlenary Lectures1. THE GREE
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27. WEAR CHARACTERISTICS OF HYBRID
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Tribometry57. PRELIMINARY STUDY ON
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Plenary Lectures13 th International
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Serbian TribologySocietySERBIATRIB
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Figure 4. Diagram of the height and
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Realization of the approach is base
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edge without chamfer and smaller ra
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Figure 7. Accumulated tool life in
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Figure 13. Calculated and measured
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Friction deformation of the bronze
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engine cylinders of 2-cylinder-twot
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Table 1: Chemical composition of sa
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Table 4: Comparative wear-resistanc
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- measuring of coating thickness h
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Figure 5. Functional scheme of the
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Table 2. Test results for massive w
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knowledge transfer in the field ofm
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Table 1. Parameters of the electroc
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Figure 6. Wear resistance by linear
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coatings and observed their good we
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c)a)Figure 2: SEM images and micros
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Room temperature 300°CNi/µSiCNiNi
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COF [-] COF [-]Fig.9: COF graphs at
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about 260 nm is related to isolated
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contact’s conformity [18] they ob
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In order to calculate the metallic
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microscopic inspection of the Rp3 s
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otating plate. The shaft passes thr
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similar trends of variation are obs
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smooth, gear fiber-mild steel rough
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[2] Tabor, D.: “Friction and wear
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(10, 50 and 100 N) against surface
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[9] B.R. Gligorijevic, A. Vencl, B.
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dielectric properties, high resista
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parameter, Sv, was slightly influen
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dependence of roughness height and
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Polyethylenes with a molecular weig
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[9] K.S. Kanaga Karuppiah, A.L. Bru
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MgCO3•CaCO3 (13% Mg), and carnall
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fully compatible with MRI/MSCT imag
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5. CONCLUSIONThe magnesium alloys a
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Zinc dialkyldithiophosphate (ZDDP)
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C- Lower deposits with NPNA on comb
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films. Carraro et al. [10] examined
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PlateCount No.Critical Load ( N)120
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solid melt of ZA27 alloy using mech
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SiC particles are uniformly distrib
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in number of micro-cracks and clust
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PBT has the average values of the f
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mechanical pressure and thermal loa
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3. EXPERIMENTAL RESULTSTaking into
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[12] L. Blunt De, X. Jiang: Advance
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2. EXPERIMENTALTESTING2.1 MaterialT
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figure 3a it could be seen that the
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and lubrication is done so that the
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5. CONCLUSIONFigure 11. The accumul
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esistance was found for composite c
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onze, which is embedded within the
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The test contact pair meets the req
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complete. The SEM analysis maycontr
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tg( ) tg 100, [%] (2)tgwhere are:
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corresponding to the maximum value
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electrostatics [17]. Due to the fle
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250nm size have been observed, acco
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ETH Zurich, Switzerland, where all
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comparison with the synthetic reinf
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3. RESULTS AND DISCUSSION3.1 Micros
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(a)(b)Figure 4. Showing (a) variati
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composites. But the composite compo
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coated and uncoated region after ad
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has been measured between the top s
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Fig. 9 shows the wear track obtaine
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Mica samples preparationFor the ads
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According to the AFM results in fig
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[21] B. G. Sharma et al.: Character
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chemical vapor deposition method wi
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analysis (a) and an approximate che
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Table 3. Friction coefficients of s
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A.K.Oleynik, V.M.Matsevity, ea.]. /
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Most of the friction units of produ
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In order to provide both high parts
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Fig. 3. The comparison the criterio
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Table 3. Experimental and calculate
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For developing the numerical model
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,eccentricities and hydrodynamic pr
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hydrodynamic regime. However, for b
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to obtain the temperature distribut
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force (pressure) between two contac
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5E-06The total displacement [m]4.5E
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[11]. Figure 5 shows s the influenc
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efficiency of use, product quality,
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38GSA. The chemical composition, de
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niobium. It should be noted that fo
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Figure 1. Friction force on side su
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exploitation this changing is signi
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2. EFFICIENCY OF CYCLO DRIVEEfficie
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Figure 6. Dependence of cyclo drive
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common for their ability to be inst
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FNF (11)R sin cos11 21 22FNF
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Normal force [N]4000350030002500200
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analytical tests. The analytical te
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Table 4. Results of zero samples of
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noticeable, and by the end of explo
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4. PLASTIC BEARING APPLICATIONSRega
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For Elastohydrodynamic film thickne
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The results concluded for different
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For Thrust Force of 40KNKrytox 215
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Krytox 215 (µ = 0.03204 Pa.s)Figur
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- Reliable exploitation tools, prim
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In addition, as a result of cyclic
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AcknowledgementThe part of this res
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Thepressure angle can be calculated
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mechanism these parameters are fina
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causes big changes of their propert
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Table 2. Impact toughness of some t
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Figure 1. Appearance of fractured f
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implementation of these new manugac
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additional energy is dissipated due
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The adopted geometry parameters are
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4. CONCLUSIONTools of virtual produ
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Figure 2. Structure of the machinin
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3. ANALYSIS OF RESULTSThe results o
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Figure 15. Surface roughness regard
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From the analysis of the diagram it
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comparison from economic, energy co
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Advantages and disadvantages of tra
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The information provided by footwea
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Force (N)5,554,543,532,521,510,50Ex
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additives, that had been, until rec
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Figure 1. Test results for samples
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Table 7. Test results of oil sample
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Input parameters- Current intensity
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edge formed into a thin line. At th
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Lower values of current are not res
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Table 1. Chemical composition of si
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flowable at high temperatures and v
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holes (pits) emerge in the shape of
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[4] W. Schatt, K-P. Wieters, Pulver
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assumption allows us to use, instea
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where P is the load, a - radius of
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determination (total running in tim
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μm, compared with Figure 17, wich
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Serbian TribologySocietySERBIIATRIB
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Especially when the chain transfer
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is obvious that this isa so-calledw
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Page 367 and 368: each of which is measured by the le
Page 371 and 372: Fractal dimensions were determined
Page 375 and 376: Figure 3. Modified force acting sch
Page 377 and 378: 0.25Lubricant: L3DC 04Friction coef
Page 379 and 380: nanocomposites. The influence of fi
Page 381 and 382: 4. RESULTS AND DISCUSSION4.1 Morpho
Page 383 and 384: Figure 6. Loading and unloadin vers
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Page 389 and 390: The material after qualifying the r
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Page 393 and 394: Degradation & Stability, Vol. 69, N
Page 395 and 396: conformance to researchers’ requi
Page 397 and 398: This part is assembled of pneumatic
Page 399 and 400: matrixes describe the state of the
Page 401 and 402: values influence of themeasurement
Page 403 and 404: Figure 1. Friction stir weldinga -
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Page 407 and 408: M fr / T [-] [-]10.90.80.70.60.50.4
Page 409 and 410: M fr / T [-]10.90.80.70.60.50.40.30
Page 411: experimentally determined that for
Page 417 and 418: 2.1 The life cycle of the reportThe
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Page 425 and 426: uticaja na osnovu kompozita, a time
Page 427 and 428: 5. ZAKLJUČCIStruktura tiksolivene
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Page 431 and 432: vizuelno, na dnevnoj svetlosti, pod
Page 433 and 434: LITERATURA[1] Зинченко В.
Page 435 and 436: Slika 1. Rotorni bager - glodar VII
Page 437 and 438: stvaraju sliku stanja i svoja zapa
Page 439 and 440: njihovih kotrljanih elemenata. Mere
Page 441 and 442: postupka i uticaja parametara depoz
Page 443 and 444: posledica različite raspodele mikr
Page 445 and 446: ZrO 2 Y 2 O 3 je takođe zbog oksid
Page 449 and 450: 3.2 Pneumatska osetljivostOblast pr
Page 451 and 452: p mg (δ), koji je zbog malih struj
Page 453 and 454: PNEUMATIC PROBE HEAD SELECTION FOR
Page 455 and 456: 1. Podsistem kopanja2. Podsistem pr
Page 457 and 458: Slika 3. Kriva habanjaNa tom dijagr
Page 459 and 460: Mjereni su parametri habanja i pril
Page 461 and 462: preše prevladavaju kombinirani uvj
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a) b)Slika 5. Karakteristična mikr
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varijantnih materijala u dostavnom
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Jovanović D. 414, 446KKaleicheva J
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CIP - Каталогизација
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