Tribology in Industry

415-430

Authors: M.B.A. Aidoudi, J. Bessrour

The present paper represents a study of the effect of surface roughness in elastic-plastic micro contact between two cylinders in contact along their external generatrix by finite element analysis. This is the first study in the micro-scale geometry to analyze this particular contact used in industrial problem of fluid heat tracing. Two types of frictionless contact are investigated numerically. One examines the contact between two random rough cylindrical surfaces with Gaussian statistics for different topographies. The other proposed the contact between sum cylindrical surface which include the roughness and the elasticity of the both rough surfaces into contact, with perfectly smooth rigid cylindrical surface. The construction of sum surface is used in order to simplify the problem of rough contact. A full description of the method and the technical of construction of sum surface is presented. As a result, it was fund a good agreement between the two models. A multiple contact configuration was analysed in the form of cylindrical surface. Numerical results obtained under elastic conditions were also validated by comparison with theoretical solution of Hertz. A sensitivity analysis is presented in order to estimate the random draw of parameters on the results. We present then results showing the effects of roughness on contact parameters. Overall, it is found that the contact parameters are quite sensitive to the roughness parameters in elastic and plastic deformation. Results show that the surface topography has a large influence on the real area of contact. As a result of that, the real contact area ratio increases with the increasing of the displacement until it reaches a maximum limit value on elastic-plastic deformation. This value, less than unity, decreases with increasing roughness.

444-451

Authors: Z. Karaguiozova, J. Kaleicheva, V. Mishev, G. Nikolcheva

A technology to improve the tribological and mechanical surface properties of iron alloys is developed based on the electroless nickel plating. The technology combines sol-gel and electroless deposition technique. Novel nanocomposite coatings are obtained consisting of Nickel-phosphorus-nanodiamond (Ni-P-ND). The ND sol is added directly to the electroless Ni-P solution. A suitable surfactant is added to achieve well-dispersed ND particles in the electroless solution to facilitate their embodiment and equal distribution in the coating. Substrates of steel 17CrNiMo6 and spheroidal graphite cast irons are used for the manufacture of the iron alloys specimens. The surface morphology and microstructure observation performed by scanning electron microscopy (SEM) and optical metallography confirms the influence of ND particles on the coating structure. The structural phase investigation by X Ray analysis indicates a transformation of the amorphous phase to a crystalline one such as Ni, Ni3P after coatings' heat treatment. The microhardness investigation by Knoop Method and wear resistance measurement in accordance with the Polish Standard PN-83/H-04302 of Ni-P and Ni-P-ND composite coatings are evaluated and compared with each other. The increase in the value of hardness and wear resistance of Ni-P composite coatings in the presence of ND particles and after heat treatment is obtained.

460-470

Authors: J. Wahlström, V. Matejka, Y. Lyu, A. Söderberg

Particulate matter with an aerodynamic diameter less than 10 µm (PM10) from car disc brakes contribute up to 50% of the total non-exhaust emissions from road transport in the EU. These emissions come from the wear of the pad and rotor contact surfaces. Yet few studies have reported contact pressures and offered sliding speed maps of the friction, wear, and particle emission performance of disc brake materials at a material level. Such maps are crucial to understanding material behaviour at different loads and can be used as input data to numerical simulations. A low-metallic pad and grey cast-iron rotor contact pair commonly used today in passenger car disc brakes was studied using a pin-on-disc tribometer at twelve contact pressure and sliding speed combinations. Maps of the coefficient of friction, specific wear rate, particle number, and mass rate are presented and discussed.

482-486

Authors: E. Feyzullahoğlu

Polymeric composites are used for different aims as substitute of traditional materials such as metals; due to their improved strength at small specific weight. The fiber reinforced polymer (FRP) composite material consists of polymeric matrix and reinforcing material. Polymeric materials are commonly reinforced with synthetic fibers such as glass and carbon. The glass fiber reinforced polyester (GFRP) composites are used with different filler materials. The aim of this study is to investigate the effects of different filler materials on adhesive wear behavior of GFRP. In this experimental study; polymetilmetacrilat (PMMA), Glass beads (GB) and Glass sand (GS) were used as filling material in GFRP composite samples. The adhesive wear behaviors of samples were carried out using ball on disc type tribometer. The friction force and coefficient of friction were measured during the test. The volume loss and wear rate values of samples were calculated according to test results. Barcol hardness values of samples were measured. The densities of samples were measured. Results show that the wear resistance of GB filled GFRP composite samples was much more than non-filled and PMMA filled GFRP composite samples.

495-505

Authors: O.P. Balogun, J.A. Omotoyinbo, K.K. Alaneme, P.A. Olubambi

This study investigates the use of Entada mannii fiber as potential reinforcement of thermoplastic composites suitable for light weight applications. Composites of 5 wt.%, 10 wt.% and 15 wt.% were produced by compression moulding with 5 wt.% Maleic anhydride polypropylene (MAAP) as compatibilizers. Tensile properties, impact strength and hardness properties of the composites were evaluated. Thermogravimetric analysis (TGA), X-ray diffractograms (XRD) and Fourier transformed infrared spectroscopy (FTIR) of treated and untreated fibers were evaluated while the fractographic analysis of surface morphology of the composites was performed using Scanning electron microscopy. The result revealed that reinforcing thermoplastic with 15 %.wt treated Entada mannii fiber revealed a greater improvement in tensile strength and Young's modulus by 58 % and 61 % respectively relative to pure PP and the hardness properties of the composite also increased by 56 % as compared with pure PP . This improvement is noticeable for the 15 wt.% treated fiber reinforced composites and could be attributed to good interfacial bonding between the fiber and the matrix. However impact strength of treated fiber composite revealed an improvement with 10 wt.% treated fiber composites by 48 % relative to Pure PP. Fracture surface images of treated fiber reinforced composites revealed less fiber pullout while the TGA showed the treated fiber degrades at higher temperature as compared with untreated fiber. Thus, the cellulose percentage crystallinity index of the treated fiber increases from 47.9 % to 57 % as a result of the influence of alkaline treatment.

519-526

Authors: S. Perepelkina, P. Kovalenko, R. Pechenko, K. Makhmudova

This paper deals with the research of friction coefficient in tribopairs made of the polymers that are the most commonly used in rapid prototyping technologies. Parts manufactured with the use of a 3D printer with different settings of printing were chosen as samples for the experimental research. Friction coefficient and the temperature in the contact area during the runtime were measured using a universal friction machine MTU-1. The machine allows us to carry out tribological experiments using different contact schemes with or without lubricants. For this research, the scheme "plate-on-plate" was chosen. No lubricants were used. Wear of the samples was estimated after the experiments. Analysis of the experimental data has shown that changing of 3D printing settings has significant influence not only on the strength and stiffness of the parts, but also on the quality of the surface that affects the tribological properties of the tribopairs. The results of this research allow us to choose optimal settings for 3D printing depending on the required tribological properties of the parts, such as friction coefficient and wear.

536-546

Authors: L. Capitanu, L.-L. Badita, V. Florescu

Aim of this project was to study the fretting behaviour of the cemented femoral stem fixation of a total hip prosthesis, trying to capture the loss of contact between the femoral stem and polymetylmethacrilate cement fixation. To have a landmark, studies were performed compared with cementless fixation, where no fretting phenomenon occurs, on real prostheses, under biological 3D loading conditions. A fatigue test device, installed on a servo-hydraulic triaxial dynamic testing machine was used. It allowed monitoring the flexion-extension, abduction-adduction, inner-outer rotation movements, and the variation of the torsional torque, depending on normal loading. The test ends when the sample does not fail after 2000000 cycles, or when it has reached a predetermined number of cycles. Test fluid medium used was NaCl mixed with distilled water, a favourable environment for appearance of fretting corrosion. After the failure of stem fixation at 2450000 cycles, the mantle of bone cement remaining adherent on femoral stem was removed. Microscopic inspection of the femoral stem and of the inner part of the polymetylmethacrilate mantle demonstrated the existence of corrosion of the femoral stem surface beneath the cement mantle, and Fe2O3 deposits on the femoral stem surface and on the inner part of the mantle.

559-565

Authors: B. Castaños, C. Bazurto, L. Peña-Parás, D. Maldonado-Cortés, J. Rodríguez-Salinas

Proper grease selection is essential for the electrical industry to minimize friction and wear between the components of circuit breakers under mechanical contact. In this investigation, the tribological properties of commercially available greases for industrial circuit breakers were evaluated. Three tribological tests were performed: the ITeE-PIB Polish Method for testing lubricants under scuffing conditions (extreme pressure, EP), a four-ball test under ASTM D 2266 (anti-wear, AW), and a ball-on-disk test based on ASTM G-99. The worn materials were characterized with an optical 3D profilometer measurement system and a scanning electron microscope (SEM). Additionally, selected greases with the best tribological performance were tested on a testing bench intended for circuit breakers, according to electrical safety standards, which validated the results obtained in the laboratory.

277-282

Authors: F. Mindivan

The effects of Graphene Nanoplatelet (GNP) on mechanical and tribological properties of Polyamide 6 (PA6) were studied. The composites were blended using twin-screw extruder and subsequently injection molded for test samples. Mechanical properties were investigated in terms of microhardness, scratch hardness and Young’s modulus measurements and tensile test. The tribological behavior of composites was studied by using ball-on-disc reciprocating tribometer. Recent studies showed that the addition of GNP in PA6 matrix resulted in enhancement of mechanical and tribological properties.

294-301

Authors: J. Kaleicheva, V. Mishev, Z. Karaguiozova, G. Nikolcheva, A. Miteva

The tribological characteristics of spheroidal graphite cast irons with and without nanosized additives are investigated. The tests are performed as in cast iron condition as well after austempering. The spheroidal graphite irons are undergone to austempering in the bainite field, including heating at 900 °? for an hour, after that isothermal retention at 280 °?, 2 h and at 380 °C, 2 h. The lower bainitic and upper bainitic structures are formed during the process. Nanosized additives of titanium carbonitride and titanium nitride TiCN+TiN influence on the graphite phase characteristics and on the microstructure of the cast and austempered spheroidal graphite irons. The changes in the micro structure the irons with nanoadditives lead to an abrasive wear resistance increase. The formation of the strain induced martensite from the retained austenite in the friction contact area during wear is determined in the austempered irons. This is the reason for the wear resistance increase of the irons. The experimental testing of the wear is carried out by cinematic scheme tapper-discunder friction on the fixed abrasive. The microstructure of the patterns is observed by optical and quantitative metallography, X-Ray analysis, SEM and EDX analysis. The hardness testing is performed by Brinnel and Vickers methods.

307-318

Authors: N. Panwar, R.P. Poonia, G. Singh, R. Dabral, A. Chauhan

In present study, Red mud, an industrial waste, has been utilized as a reinforcement material to fabricate Aluminium 6061 matrix based metal matrix composite. Taguchi L18 orthogonal array has been employed for fabrication of composite castings and for conducting the tribological experimentation. ANOVA analysis has been applied to examine the effect of individual parameters such as sliding condition: dry and wet, reinforcement weight fraction, load, speed, and sliding distance on specific wear rate obtained experimentally. It has been found that tensile strength and impact energy increases while elongation decreases, with increasing weight fraction and decrease in particle size of red mud. The percentage contribution of the effect of factors on SWR is Sliding condition (73.17), speed (7.84), percentage reinforcement (7.35), load (5.75), sliding distance (2.24), and particle size (1.25). It has also been observed that specific wear rate is very low in wet condition. However, it decreases with increase in weight fraction of reinforcement, decrease in load and sliding speed. Al6061/red mud metal matrix composites have shown reasonable strength and wear resistance. The use of red mud in Aluminium composite provides the solution for disposal of red mud and can possibly become an economic replacement of Aluminium and its alloys.

329-333

Authors: K. Gavrilov, Y. Goritskiy, I. Migal, M. Izzatulloev

This article describes, develops and applies approach of the interaction of rough surfaces for one of the tasks of simulation of tribological systems of the piston engine. In this paper we described the general approach to building a model of interaction between rough surfaces, leading to the analysis of the Markov process. Given the initial data and the method of calculating the trajectory of movable elements on the lubricating layer, we determined the tribological parameters defining the service life of tribological systems of the piston engine on the example of crankshaft bearings.

340-348

Authors: D. Stamenković, M. Banić, M. Nikolić, M. Mijajlović, M. Milošević

There are many standards relating to the anti-slip properties of footwear and flooring. These standards describe the different test methods and procedures for determining the footwear and floor slip resistance in different conditions. In this paper authors systematize the standards in this field applied in the EU and in Serbia and cite the Serbian institutes which are certified for this type of testing. In addition, the authors have carried out an analysis and comparison of the tests that are defined in these standards, indicating their advantages and disadvantages. Importance of the static and kinetic friction testing in determining the anti-slip properties of footwear and flooring is specifically indicated. Considering the current standards in area of slip resistance of the footwear and floor covering authors have determined the testing conditions for laboratory measuring the friction forces of different floor and footwear materials. The laboratory measurement has carried out at Faculty of Mechanical Engineering in Niš. The measuring results and their analysis are presented in the paper, as well.

357-363

Authors: M.A. Ramadan, R. Reda

The present work studied the effect of filling epoxy matrix by different types and concentrations of nanoparticles on the friction and wear behaviors. Various concentrations (0.2 %, 0.4 %, 0.6 %, 0.8 % and 1 wt.%) of multi walled carbon nano tubes (MWCNTs), aluminum oxide (Al2O3), and silica (SiO2) nanoparticles were used to reinforce epoxy matrix. These epoxy nanocomposites are widely used as indoor flooring tiles in schools, boutiques, hospitals, offices, conference rooms, homes, trade fair stands and homes for the aged. Experiments involved sliding of the epoxy nanocomposite specimens against rotating steel disc at dry sliding condition. Experiments were carried out using a test rig of pin-on-disc, designed and manufactured for the test. The friction force was measured using load cell which connected with a digital screen to detect the friction force. All experiments were done at room temperature and carried out at constant normal load (7 N), constant speed (0.93 m/sec) and constant running time (300 seconds). The worn surfaces were investigated with back scattered scanning electron microscopy (SEM). Based on the observations in the present work, it was found that addition of the tested filling nanoparticles have greatly affected the friction and highly improves wear resistance.

378-390

Authors: G. Chen, Y. Liu, G. Lodewijks, D.L. Schott

The handling of iron ore bulk solids maintains an increasing trend due to economic development. Because iron ore particles have hard composites and irregular shapes, the bulk solids handling equipment surface can suffer from severe sliding wear. Prediction of equipment surface wear volume is beneficial to the efficient maintenance of worn areas. Archard’s equation provides a theoretical solution to predict wear volume. To use Archard’s equation, the coefficient of sliding wear must be determined. To our best knowledge, the coefficient of sliding wear for iron ore handling conditions has not yet been determined. In this research, using a pin-on-disk tribometer, the coefficients of sliding wear for both Sishen particles and mild steel are determined with regard to iron ore handling conditions. Both naturally irregular and spherical shapes of particles are used to estimate average values of wear rate. Moreover, the hardness and inner structures of Sishen particles are examined, which adds the evidence of the interpretation of wear results. It is concluded that the coefficients of sliding wear can vary largely for both Sishen particle and mild steel. The wear rate decreases from transient- to steady-state. The average coefficient of sliding wear is capable of predicting wear with respect to long distances at the steady-state. Two types of sliding friction are distinguished. In addition, it is found that the temperature rise of the friction pairs has negligible influence on wear rate.

400-414

Authors: J.L. Olajide, I.O. Oladele, O.J. Odeyemi, S.O. Babarinsa

Of late, some biological wastes have proven to be reliable candidates in promoting the economic viability of developing polymeric composites. However, the field-proven reliability prediction of such materials during service life requires extensive characterization. In this research, the influence of 75 µm bovine femur ash subjected to two-step calcination process on spectroscopic, wear, mechanical, water absorbent and biocorrosive properties of epoxy/femur waste biocomposites was investigated. The test materials were developed via open mould casting and subjected to preferred characterizations apropos of the abovementioned properties. Elemental constituents of the biocomposites and the ash were determined by energy dispersive x-ray spectroscopy with scanning electron microscopy and x-ray fluorescence spectroscopy, respectively. The investigated properties were studied dependent on predetermined volume fractions of the ash in epoxy matrix. Observations from the experimental results revealed that properties’ enhancement was not specific to either low or high volume fraction of the ash in epoxy. Different properties were enhanced at different volume fractions of the ash. Nonetheless, one biocomposite approaching intermediate volume faction of the ash used, exhibited optimum combination of the investigated properties. This is a clear indication that bovine femur waste can be successfully exploited for engineering applications, especially in the areas of materials development.

145–151

Authors: A. Mohandas, N. Radhika

The aim of the work is to fabricate functionally graded aluminium (Al-Si6Cu)/ nickel coated SiC metal matrix composite using centrifugal casting route. SiC particles (53-80 µm) were coated with nickel using electroless coating technique to enhance the wettability with aluminium matrix. Several attempts were made to coat nickel on SiC by varying the process temperature (65 °C, 75 °C, and 85 °C) to obtain a uniform coating. Silicon particles coated with nickel were characterised using EDS enabled Field Emission Scanning Electron Microscope and it was found that the maximum nickel coating on SiC occurred at a process temperature of 75°C. This nickel coated SiC particles were used as the reinforcement for the manufacture of functionally graded metal matrix composite and a cast specimen of dimensions 150×90×15 mm was obtained. To ensure the graded properties in the fabricated composites, microstructure (at a distance of 1, 7 and 14 mm) and hardness (at a distance of 1, 3, 7, 10 and 14 mm) from outer periphery taken in the radial direction was analysed using Zeiss Axiovert metallurgical microscope and Vickers micro hardness tester respectively. The microstructure reveals presence of more SiC particles at the outer periphery compared to inner periphery and the hardness test shows that the hardness also decreased from outer periphery (90 HV) to inner periphery (78 HV).Tensile strength of specimen from outer zone (1-7mm) and inner zone (8-14 mm) of casting was also tested and found out a value of 153.3 Mpa and 123.3 Mpa for the outer zone and inner zone respectively. An important observation made was that the outer periphery of casting was particle rich and the inner periphery was particle deficient because of centrifugal force and variation in density between aluminium matrix and reinforcement. Functionally graded Al/SiC metal matrix composite could be extensively used in automotive industry especially in the manufacture of liners and brake drums.

168-182

Authors: W. Tillmann, L. Hagen, P. Schröder

Tungsten carbide reinforced coatings play an important role in the field of surface engineering to protect stressed surfaces against wear. For thermally sprayed coatings, it is already shown that the tribological properties get mainly determined by the carbide grain size fraction. Within the scope of this study, the tribological characteristics of iron based WC-W2C reinforced arc sprayed coatings deposited using cored wires consisting of different carbide grain size fractions were examined. Microstructural characteristics of the produced coatings were scrutinized using electron microscopy and x-ray diffraction analyses. Ball-on-disk test as well as Taber Abraser and dry sand rubber wheel test were employed to analyze both the dry sliding and the abrasive wear behavior. It was shown that a reduced carbide grain size fraction as filling leads to an enhanced wear resistance against sliding. In terms of the Taber Abraser test, it is also demonstrated that a fine carbide grain size fraction results in an improved wear resistant against abrasion. As opposed to that, a poorer wear resistance was found within the dry sand rubber wheel tests. The findings show that the operating mechanisms for both abrasion tests affect the stressed surface in a different way, leading either to microcutting or microploughing.

192-197

Authors: P. Kovalenko, S. Perepelkina, T. Korakhanov

This paper deals with the processes occurring on the surfaces of materials during the interaction between metal and non-metal parts of various biomechatronic devices, such as prostheses, orthoses and exoskeletons. These mechatronic systems require careful selection of materials for design and manufacturing of their parts taking into consideration not only mechanical properties of the materials, but also their tribological characteristics. Friction pairs duralumin – fluoropolymer and stainless steel 100CrMn6 – fluoropolymer were chosen for the research as the samples. Experimental research was carried out with the use of the universal friction machine MTU-1. For this research, the scheme “plate-on-plate” was used without lubricants. Friction torque, friction coefficient and the temperature in the contact area versus the runtime were obtained as a result of the experiments. Furthermore, estimation of wear of contacting samples was performed. Analysis of the results allowed us to choose suitable materials for design and manufacturing of orthoses, prostheses and exoskeletons.

207-210

Authors: N.K. Myshkin, A.Ya. Grigoriev, I.N. Kavaliova

Sunflower, corn, rapeseed, olive, and linseed oils were used for investiga-tion. Their fatty-acid compositions have been evaluated by gas chroma-tography. The tribological properties were determined with a four-ball machine. Flash and set points, static and dynamic viscosity of the oils were estimated by standard methods. The results of tests show that refined plant oils possess better tribotechnical properties than the base mineral oil without additives. It was found that their antiwear and bearing resistance properties correlate with the structure of fatty acids molecules. It is demonstrated that the activation of unsaturated bonds as a result of the triglycerides oxidation has a positive influence on friction due to tribopolymerization and film formation on the contact surfaces.

219-227

Authors: P. Amuthakkannan, V. Manikandan, M. Ayyanar Raja, S. Rajesh

Aluminum alloy based metal matrix composite participate have a wider applications in wear resistance applications. Attempt made in current study is that, basalt fiber reinforced aluminum metal matrix composite have been prepared using stir casting method. Different weight percentage of basalt fiber reinforced with Al (6061) metal matrix composites are used to study the wear resistance of the composites. For wear study, percentage of reinforcement, normal load and sliding velocity are the considered as important parameters. To study the effect of basalt fiber reinforcement on the dry sliding wear of Al6061 alloy composites the Pin On wear tester is used. Initially hardness of the composites was tested, it was found that increasing reinforcement in the composite hardness value of the composites also increased. Based on the Grey relation analysis (GRA) the effects of wear resistance of the composites were studied.

238-247

Authors: G. Globočki Lakić, B. Sredanović, D. Kramar, J. Kopač

High Pressure Jet Assisted Machining (HPJAM) in turning is a hybrid machining method in which a high pressure jet of cooling and lubrication fluid, under high pressure (50 MPa), leads to the zone between the cutting tool edge and workpiece. An experimental study was performed to investigate the capabilities of conventional and high pressure cooling (HPC) in the turning of hard-to-machine materials: hard-chromed and surface hardened steel Ck45 (58 HRc) and hardened bearing steel 100Cr6 (62 HRc). Machining experiments were performed using coated carbide tools and highly cutting speed. Experimental measurements were performed for different input process parameters. The cooling capabilities are compared by monitoring of tool wear, tool life, cooling efficiency, and surface roughness. Connection between the tool wear and surface roughness is established. Experimental research show that the hard turning with carbide cutting tools and HP supply CLF provides numerous advantages from the techno-economic aspect: greater productivity, reduce of temperature in the cutting zone, improved control chip formation, extended tool life, low intensity of tool wear, surface roughness in acceptable limits, significant reduce of production costs related to the CLF.

255-259

Authors: I. Bijelić, N. Mor, M. Živković, V. Tubin, T. Stožinić

Experimental research was carried out on the tribometer of high reliability of measurement. The paper discusses the impact of normal contact pressure on the value of the coefficient of friction. Elements that are in contact are filled steel rollers with different mass and diameters that slide on the hollow roller shaped like a ring. These contact elements are completely submerged in oil and have identical lubrication requirements. The results of this study indicate the significant influence of the level of normal load and contact pressure on the coefficient of friction.

270-276

Authors: F. Mindivan, H. Mindivan, C. Darcan

In the present study, the surface of commercial pure (Grade 2) titanium was coated with electroless Ni–B. The surface morphology, microstructure and phase identification were analysed by X-Ray Diffraction (XRD) and Field Emission Gun Scanning Electron Microscope (FEG-SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS). The tribocorrosion performance in a laboratory simulated artificial saliva was investigated using a reciprocating ball-on-plate tribometer coupled to an electrochemical cell. The antibacterial property of the electroless Ni–B film coated on pure titanium was basically investigated. From this study, it may be concluded that this electroless Ni–B coating process cannot only improve the hardness and tribocorrosion performance of the pure titanium, but can also provide antimicrobial activity.

1-8

Authors: N. Radhika

LM25 aluminium alloy reinforced with 15 wt% SiO2 metal matrix composite was fabricated by liquid metallurgy technique. Microstructure of the fabricated composite specimen was observed using inverted metallurgical microscope and result showed uniform distribution of reinforcement particles in the matrix. The dry sliding wear behaviour of LM25/SiO2 composite was analyzed by conducting experiments using pin-on-disc tribometer. Taguchi’s method was used for designing the number of experiments and L16 orthogonal array was developed for wear analysis. Optimization of parameters like applied load (10 N, 20 N, 30 N, 40 N), sliding velocity (0.5 m/s, 1 m/s, 1.5 m/s, 2 m/s) and sliding distance (500 m, 1000 m, 1500 m, 2000 m) was done using Signal-to-Noise ratio analysis and Analysis of Variance. ‘smaller-the-better’ characteristic was chosen to analyze the dry sliding wear behaviour. Results found that load (69.17 %) had the highest impact on wear rate followed by sliding velocity (18.04 %) and sliding distance (1.5 %). The regression equation was developed and it was validated with confirmatory experiment. Scanning Electron Microscope analysis was done to observe the mechanism of the worn out composite specimen and found more delamination at the load of 40 N.

20-30

Authors: K.A. Najar, N.A. Sheikh, M.A. Shah

An experimental investigation has been carried out to study the influence on the performance characteristics of a cutting tool material notably known as cemented tungsten carbide (WC-Co). A comparison has been documented between nanocrystalline diamond (NCD) and microcrystalline diamond (MCD) coatings deposited on two cemented tungsten carbide (WC-Co) substrates with the architectures of WC-Co/NCD and WC-Co/MCD, using hot filament chemical vapor deposition (HFCVD) technique. In the present work, the friction characteristics were studied using ball-on-disc type linear reciprocating micro-tribometer, under the application of 1–10 N normal loads, when sliding against smooth alumina (Al2O3) ceramic ball for the total duration of 20 min, under dry sliding condition. Nanoindentation tests were also conducted using Berkovich nanoindenter for the purpose of measurement of hardness and elastic modulus values. However, the average value of friction coefficient (COF) corresponding to MCD and NCD coatings decrease from ~0.37–0.32 and ~0.30–0.27, respectively when the load is increased from 1–10 N. However, for conventional WC-Co substrate the average COF increases from ~0.60–0.75, under the same input operating conditions. The wear tracks formed on the surfaces of NCD, MCD and WC-Co, after sliding were characterised using Raman spectroscopy and scanning electron microscopy (SEM) techniques. Therefore, the results will serve breakthrough information for the designer to design the cutting tool or mechanical component using this novel coating procedure.

45-49

Authors: G.R. Igtisamova, N.O. Kovalev

The paper considers improvement of screw dies of mobile coiled tubing unit injector through the change in screw die's design parameters with further mounting of metal-ceramic based friction material. Comparison of designs of unit injector screw dies was carried out and reliability evaluation of an improved coiled tubing transporter unit was executed.

63-72

Authors: F.O. Kolawole, S.K. Kolawole, J.O. Agunsoye, S.A. Bello, J.A. Adebisi, O.C. Okoye, S.B. Hassan

Characterization of synthesized cassava leaf nanoparticles (CLNPs) was carried out using SEM/EDX and Gwyddion software, XRD and TEM for cassava leaves (CL) ball milled at 36, 48, 60 and 72 hours. The morphological study was done using SEM and the Gwyddion software was used to determine the particle sizes from the SEM images. The particle size range for the un-milled cassava leaves (CL) was between 1.88 + 0.09 to 19.53 + 0.98 µm. After milling for 36, 48, 60 and 72 hours the average particle sizes were 4.96 + 0.25, 3.51 + 0.18 µm, 86.90 + 4.35, 74.50 + 3.73 nm respectively. Crystallite size of 23.94 + 1.20 nm was obtained by XRD using Scherrer equation after milling for 72 hours and the XRD results revealed the presence of compounds such as SiO2, CaCO3, Ca2(SO4)2H2O and CaC2O4(H2O). Furthermore, TEM was used to determine nanoparticles after milling for 72 hours and the particle size ranged from 9.16 + 0.46 to 58.20 + 2.91 nm for cassava leaf nanoparticles (CLNPs) and EDX results showed trace element of O, Si, Ca, K, Fe and S in the CL milled for 72 hours . FTIR was also carried out to determine the nature of bond that exist in the organic compounds in CLNPs and GCMS analysis was used to reveal the organic compounds that were present in CLNPs. Anti-Corrosion coatings reduces corrosion activities to the bearest minimum.

82-89

Authors: P. Novotny

A solution of radial slide bearing dynamics and tribology incorporating the influences of real surface roughness contacts or the influence of surface roughness on bearing lubrication is presented in this paper. Finite difference method for Reynolds equation discretization, finite element method for calculation of elastic deformations, Gauss-Seidel’s method for iterative solution of discretized equations or Newmark’s algorithm are the methods employed in the proposed solution approach. The coupled structural-fluid solver considering mixed lubrication conditions of the radial bearings is the result. The proposed algorithms are presented for highly loaded radial slide bearing of internal combustion engine.

100-109

Authors: H. Mohassel, F. Malekabadi, M. Jebreili, M. Zehsaz, F. Vakili-Tahami

We have investigated the influence of post-shot peening on Mo-coating as compared to substrate steel 16MnCr5 (according to ZFN-413 A). Shot peening of carburized steel discs with and without Mo-coating was performed by using Shot size S230, Almen intensity 0.42 mm ’A’ and exposure time 96 sec. Tribological properties were analyzed, using pin-on-disc tribometer apparatus, under dry sliding conditions at different specific applied loads, sliding velocities and distance. Typical standardized methods were used for studying of surface integrity parameters (micro-hardness, topography and surface roughness). Surface morphology of the Mo-coating specimens with and without Shot Peening before and after wear was evaluated by Scanning Electron Microscopy. The results showed that shot peening after Mo-coating has considerable effect on improving wear resistance and because of having low friction coefficient has showed better wear behavior and tribologi cal properties over that of the un-peened Mo-coating.

120-128

Authors: M.F. Abd Al-Samieh

The mechanism of oil film with a thickness in the nanoscale is discussed in this paper. A polar lubricant of propylene carbonate is used as the intervening liquid between contiguous bodies in concentrated contacts. A pressure caused by the hydrodynamic viscous action in addition to double layer electrostatic force, Van der Waals inter-molecular forces, and solvation pressure due to inter-surface forces is considered in calculating the ultrathin lubricating films. The numerical solution has been carried out, using the Newton-Raphson iteration technique, applied for the convergence of the hydrodynamic pressure. The results show that, at separations beyond about five molecular diameters of the intervening liquid, the formation of a lubricant film thickness is governed by combined effects of viscous action and surface force of an attractive Van der Waals force and a repulsive double layer force. At smaller separations below about five molecular diameters of the intervening liquid, the effect of solvation force is dominant in determining the oil film thickness.

136-143

Authors: S. Bhaumik, S.D. Pathak

The wear and surface morphology between steel (EN24, 22-24Rc)-steel (EN 31, 58-60Rc) contacts was investigated in presence of friction modifiers based (micro-graphite/nano particles- multi wall carbon nano tubes and zinc oxide) mineral oil. Though a decrease in wear was observed (upto a certain concentration of nano friction modifiers) but a weight-gain in pins after the tests was observed for all tests with ZnO nanoparticles while weight loss was observed in tests with multi wall carbon nano tubes and graphite particles based oil samples. Surface characterization of the worn surfaces showed more surface deteriorations in case of mineral oil (no friction modifiers) and mineral oil with graphite as compared with nano particles/tubes based lubricants. The occurrence of a tribo film due to the deposition of nano particle and the formation of a modified layer on the pin surfaces are likely to be responsible for the reduction of coefficient of friction and better surface roughness. Apart from investigating the wear behaviour between two steel surfaces under micro and nano particles based lubricant and analysing the surfaces of the samples a part of the work was also focussed on the weight gain after tribo tests with ZnO nano particle additions.