BALTTRIB, Proceedings of International Conference

INVESTIGATION OF TRIBOLOGICAL PROPERTIES OF POLYMER GREASE MANUFACTURED FROM POLY ALPHA OLEFIN WITH BORON NITRIDE

Atakan Bayar, Dr. Gökçe Mehmet Ay — Fri, 13 Oct 2023 00:00:00 +0300

Greases are a type of lubricant that has higher viscosity. Manufacturing greases are conducted by mixing base oils with calcium, sodium, or lithium mineral salts. Manufacturing process is complex and changes in parameters results significant change in Grease properties. The increase in mineral salts costs and their effect on nature caused researchers to look for alternative materials that can replace mineral salts. A novel method for manufacturing grease is to use polymers as thickener agents. In this study, 12% polypropylene was used to produce grease from poly alpha olefin. In order to increase grease’s high-pressure properties, 2% hexagonal boron nitride was added. Manufactured grease was compared to lithium grease with hexagonal boron nitride addition. Both samples were tested on ball-on-disc tribometer on mirror polished 4140 and results were discussed.

VISCOMETRY, VOLATILITY AND STABILITY OF DEEP EUTECTIC SOLVENTS FROM BETAINE

Dr. Dalia Bražinskienė, Dr. Tadas Matijošius, Dr. Svajus Asadauskas — Fri, 13 Oct 2023 00:00:00 +0300

Deep eutectic solvents can be formed from solids without any reaction or ionic exchange. Recently, natural deep eutectic solvents (NADES) are gaining popularity in extraction, lubrication or cooling, in particular betaine-based ones. A series of betaine formulations with xylitol and glycerol as H-bond donors were prepared and tested. A blend of betaine and glycerol at 1:2 wt. ratio recorded 456 mm²/s and 25.2 mm²/s at 40 ℃ and 100 ℃, while that of betaine and xylitol was much more viscous with 234 mm²/s at 100 ℃. Their volatility was studied by exposing thin films of NADES on steel and aluminum surfaces at 90 ℃. Vaporization rates depended on the molecular weight of H-bond donors and their thermal/oxidative resistance. Initially, both combinations showed similar lack of volatility, but in long term testing xylitol-based NADES turned out significantly less volatile than those of glycerol. Although viscosities were higher than those of conventional organic solvents, broad viscometric range and satisfactory stability imply many promising applications for NADES.

INVESTIGATION OF TRIBOLOGICAL PROPERTIES OF POLYMER GREASE MANUFACTURED FROM PALM ESTER WITH BORON NITRIDE AND POLY ALPHA OLEFIN WITH BORON NITRIDE

Mr. Yavuz Hıdır Bulutcu, Mr. Atakan Bayar, Dr. Gökçe Mehmet Ay — Fri, 13 Oct 2023 00:00:00 +0300

Greases are lubricants that are used to reduce friction, heating, distortion, torsion in gears and machines. General method of manufacturing grease is using mineral salts. As mineral salts become more expensive, research for alternative materials that can replace grease increased. A novel method for manufacturing grease is to use polymers as thickener agents. In this study, 12% polypropylene was used to produce grease from palm ester and poly alpha olefin, which are different greases from each other. In order to increase greases’ high-pressure properties, 2% hexagonal boron nitride was added. Manufactured palm ester greases were compared to poly alpha olefin greases which have been produced. Both samples were tested on ball-on-disc tribometer on mirror polished 4140 and results were discussed

VISCOSITY MODELS OF C60 FULLERENE MINERAL OILS AND COMPUTATIONAL FLUID DYNAMICS ON PISTON RING

PhD Cand. Elias Tsakiridis; Prof. Pantelis George Nikolakopoulos — Fri, 13 Oct 2023 00:00:00 +0300

To improve even more the efficiency in automotive engines, it is crucial to fully understand the generation of friction in its components. In recent years the usage of mineral and synthetic or semi-synthetic oils has increased. Nowadays worldwide massive research over nanoparticles and as a result nanolubricants has taken place. Results of research under laboratory conditions on the aging of engine commercial oils with different performance levels (such as mineral SAE 30, synthetic SAE 10W40) are presented in this paper. It is described that the action of pressure and temperature play a key role of the engine oils behaviour. The aging of lubricant causes changes to its dynamic viscosity. In this work an investigation was carried out using CFD simulations and piston ring-cylinder problem. The friction as well as the absolute pressure has been measured for all the crankshaft angles. The thermal problem has also been solved due to the fact that temperature variations affects on the oil viscosity. The temperature and the piston ring velocity varied according to the angle of the crankshaft.

BIODIESEL FUELS BASED ON VEGETABLE OILS: ENVIRONMENTAL SOLUTION IN THE OPERATION OF VEHICLES

Fri, 13 Oct 2023 00:00:00 +0300

The worldwide increasing demand for energy prompts scientists to focusing their research fields at developing sustainable processes for using renewable source of energy. Recently, the depletion of fossil reservoirs become really dramatic for European Countries due to geo-political crises and the high concern for global warming, caused by greenhouse gas emissions from the combustion of

fossil fuels, render the use of waste biomass as energy feedstock very interesting from an economic and environmental point of view. Although the EU banned the production of petrol and diesel automotives by 2035, the employing of biodiesel from waste biomass seems a very interesting alternative, solving problems connected to both fossil depletion and waste disposal.

The purpose of this article is to study the operational and lubricating properties of methyl esters of rapeseed oil, methyl esters of hemp oil, isopropyl esters of rapeseed oil.

MODELLING OF TEMPERATURE FLASHES IN THE CONDITIONS OF SLIDING OF DISCRETE ROUGH FRICTION SURFACES

Prof. Dr. Yuriy Kovalchyk, Prof. Dr. Volodymyr Shyrokov, Dr. Oleksii Shyrokov — Fri, 13 Oct 2023 00:00:00 +0300

A summarized mathematical model for the calculation of temperature flashes under sliding interaction of a microlug on the “discrete and periodic” friction surface is proposed. It takes into consideration the periodic discreetness of friction surface and also its connection with metallophysical structure

AN EXPERIMENTAL APPROACH OF ELECTRORHEOLOGICAL FLUID DAMPERS DESIGN

Prof. Pantelis George Nikolakopoulos — Fri, 13 Oct 2023 00:00:00 +0300

As far as nowadays the technology continues to advance, the need for vibration isolation becomes increasingly necessary. Electro-Rheological Fluid (ERF) dampers have been proposed for vibration control. This work presents an experimental study of Electro-Rheological (ER) dampers that could be used mainly in vehicle suspension systems. So far, an experimental setup of a double cylinder stroked by a single cross head is established, in order to investigate the vibration performance of an electrorheological fluid damper, under different electric fields. The electrorheological fluid used for the experiments is a mixture of SAE 10 oil and zeolite particles. The major findings are the hysteresis loops and the damping force that measured and presented for the various electric fields. It is clearly obtained that, as the electric field increases the capacity of the damping increases. Machine learning in terms of regression have been then applied for damping forces versus electric field yield further predictions

NUMERICAL MODELING OF SINGLE-ASPERITY FRICTIONAL CONTACT WITH ADHESION

PhD C. Alexandros Palaiologos, Prof. Pantelis George Nikolakopoulos — Fri, 13 Oct 2023 00:00:00 +0300

In our research, the elastic contact between a sphere and a flat surface is investigated, under the combination of normal and tangential loads, with the simultaneous presence of friction and adhesion. Based on the Boussinesq-Cerruti integral equations, a numerical model was created to calculate the surface tractions and displacements. Maximum shear tractions on the contact interface, and therefore friction, are governed by a bond/material failure mechanism instead of the typical Coulomb friction law. Adding to the generality of our model, a local traction-separation law was enforced for the simulation of normal and shear tractions attributed to the adhesion of the contacting bodies, therefore enabling the interaction between friction and adhesion. Our research aims to extract all the necessary mathematical formulas to describe the response of a spherical tip asperity in contact with a flat surface under normal and tangential loads in the presence of friction and adhesion

TRIBOLOGICAL ASPECTS OF POLYMERS AND THEIR COMPOSITES USED IN ADDITIVE MANUFACTURING - A REVIEW

Dr. Assoc. Prof. Abhijit Mukhopadhyay , MR. Sounak Banerjee — Fri, 13 Oct 2023 00:00:00 +0300

In the recent time different polymers as well as polymer composites are becoming the major in contender over the conventional engineering materials owing to the enhanced utility and cost advantages. Further, with the advent of different additive manufacturing techniques the uses of such polymers are also gaining priority. It is also needless to mention that tribo pairs are dominant part in all the major fields of applications. The tribology of polymer at large is very complex and there is hardly any governing mechanism. Hence, case based individual studies on tribology are an essential minimum requirement for each and every type of polymeric materials. A tribological study, that is, understanding friction and wear characteristics under relative movements have also been made for various virgin polymers. However, more studies and related data are steel needed particularly for newly developed composites. This paper intends to review, in brief, the research trends on tribological characterization including mainly the coefficient of friction and wear in tribo pairs made up of polymers and polymer composites. Sample preparation through additive manufacturing technologies, more generally by 3D printing process, have been considered. Effect of micro and nano fillers on the composites have also been discussed and compared with the tribology over their virgin counterparts. Some laboratory based results on tribological characterizations of 3D printed parts using conventional polymers have also been discussed

IMPROVED CALCULATION OF VISCOUS FRICTION IN THE MODEL OF A PIPE ROBOT

Fri, 13 Oct 2023 00:00:00 +0300

Pipe robots are used in agricultural engineering for transportation of materials. Also, they are used for cleaning of internal surfaces of the pipes. In the process of numerical investigation of dynamics of a pipe robot, a specific model for viscous friction is used. This influences the results of numerical calculations of dynamics of a pipe robot. A numerical procedure for more precise calculation of viscous friction is proposed in the paper. Results of investigations for two values of time steps are obtained: without the proposed procedure and with it. Advantages of the improved calculation of viscous friction are indicated.

CHARACTERIZATION OF AN ANTI-WEAR COATING FOR THE APPLICATION OF HIGHLY LOADED SMART THIN-FILM SENSORS

Fri, 13 Oct 2023 00:00:00 +0300

The global change in terms of economic and ecological requirements necessitates the application of innovative technologies. In addition, resources must be used more efficiently. Rolling bearings are still a part of almost all machines in industry to transmit rotational movements and mechanical loads. These systems, in addition to using high-strength and expensive materials, have higher requirements within manufacturing tolerances. Conventional machine elements in particular have optimization potential in terms of service life and reliability. To advance this potential, sensor integration for intelligent system monitoring combined with a compact electronic solution has to be realized. Technological progress in terms of digitization also makes it possible to handle large volumes of data and evaluate them in a targeted manner. Commercial applications for large rolling bearings are already available. The operating states are monitored via Condition Monitoring Systems (CMS). For this process, vibration sensors are used to identify bearing damage. Friction behavior can also be determined via additional temperature sensors. In this work, the tribological contact will be examined in more detail and sensor arrays will be applied inside the bearing system. This article presents the first stages of applying a thin-film sensor to the rolling bearing surface and analyzing it in terms of tribological loading. The thin-film sensor and the bearing surface were stressed in a defined manner by a microtribological tribometer. To protect the sensor from wear mechanisms, an aluminium oxide (Al₂O₃) thin film is deposited on the surface of the rolling bearing. After the tests, the wear track will be characterized. The focus of the investigation is the friction mechanisms and the adhesion strength. It was shown that the protective coating of the thin film sensor had an influence within the tribological system, but could be used under the given conditions.

INFLUENCE OF THE CONTACT PRESSURE ON THE WEAR BEHAVIOUR OF ASBESTOS – FREE FRICTION MATERIAL THROUGH PIN-ON-DISK TRIBOMETER

Fri, 13 Oct 2023 00:00:00 +0300

In this paper a tribological experimental analysis on a commercial asbestos – free friction material has been carried out. The aim of the investigation is to evaluate the influence of the contact pressure on the wear performances of the friction material, by the use of a pin–on–disk tribometer. Wear volume and wear rate parameters have been evaluated considering the contact load as main influence factor. A thin layer of sample material has been added to the rotating disk of the tribometer and matched to a counterface pin, in order to establish the coefficient of friction and the wear rate, under several sliding condition and different running in time test. As post processing evaluation, the surface analysis of the sample material has been carried out; the profiles of the sliding path have been used to measure the wear volume and formulate a wear rate parameter. It has been observed that the pressure contact is the main parameter to affect the tribological performances, such as temperature interface, friction and wear: higher contact pressure has led to higher values of these parameters. The most relevant result has been achieved by the evaluation of the wear rate in time; the experimental campaign has been carried through 1 h wear test. Under different test operating conditions, different trends of the wear rate in time have been observed.

ABRASIVE WEAR BEHAVIOR–MECHANICAL PROPERTIES–MICROSTRUCTURE RELATION OF Fe–C B–13 wt. % Cr Ti AND Fe C B 4 wt. % Cr 7 wt. % Cu–Ti BASED HARDFACING ALLOYS

Fri, 13 Oct 2023 00:00:00 +0300

In this research, the mechanical and tribological properties of two deposited metal of Fe–C–Cr–B–Ti alloying systems, high chromium 140Cr13Si1MnBTi alloy, and low chromium and high copper 110Cr4Cu7TiVBAl alloy applied by flux-cored arc welding process (FCAW) was studied. Samples of deposited alloy with a high content of chromium (13 % by weight of Cr) received with self‒shielded flux‒cored wire electrode without exothermic additions were investigated. For comparison, we also analyzed the deposited metal received from the self-shielded flux-cored wire electrode with exothermal addition (CuO‒Al) introduced to the core filler. It provided a low content of chromium (4 wt. %) and a high content of copper (7 wt. % Cu). The microstructure was analyzed by scanning electron microscopy X-ray and diffraction transmission electron microscopy. The introduction of the exothermic additive (CuO-Al) had a positive effect on the mechanical properties of the deposited metal, increasing the average values of microhardness, modulus of elasticity and ductility. Results of the studies had showed that the introduction of exothermic addition (CuO‒Al) to the core filler of the flux‒cored wire electrode provides the highest resistance of the deposited metal to abrasion wear due to additional alloying by copper and reduction in grain size.

TRIBOLOGICAL CHARACTERISTICS OF FRICTION PAIRS OF VEHICLES BRAKING MECHANISMS

Fri, 13 Oct 2023 00:00:00 +0300

In this paper by using the example of combined braking control of passenger vehicle of the segment C the estimation of influence of tribological characteristics of friction pairs of braking mechanisms to the braking process is performed. The obtained results enable to make a conclusion that at “cold” and “after cooling” braking mechanisms of the vehicle values of mathematical expectation of friction coefficient and dispersion of its values are approximately equal. The performed calculation indicates that when the friction coefficient changes by 8–20% the change of braking moment by 20–30% takes place. Thus, the difference between the largest and the smallest braking moments may be 50%, that may change the output characteristics and behavior of the investigated vehicle

STUDY OF THE INFLUENCE OF TRIBOLOGICAL AND ELECTRICAL PROPERTIES OF WINTER RAPE SEEDS ON THEIR EQUILIBRIUM ANGLE ON THE SEPARATING PLANE

Fri, 13 Oct 2023 00:00:00 +0300

In many cases, it is possible to obtain the high-quality seed material of difficult-to-separate seed mixtures of agricultural crops in the process of its post-harvest processing on electric separators, in which the working body is an inclined plane moving in an electric field. On such a plane, separation is carried out according to the set of tribological, physical-mechanical and electrical properties of the constituent components. The efficiency of electroseparation can be increased by thorough investigation of these properties both for crop seeds and for weed seeds or various types of injured grains.

It is found out that the universal criterion, on the basis of which it is possible to analyse the influence of tribological, physical-mechanical and electrical properties on the behaviour of the components of a difficult-to-separate seed mixture on the separating plane, is the angle of equilibrium of the seed on it.

The mathematical expression of the equilibrium angle is formulated, in which the shape, dimensions, roughness, material of the separating plane are represented by the friction angle j, and the electrical properties of the seeds (electrical conductivity, dielectric permittivity, etc.) – by the multiplicity of the electric force k_о.

Due to the experimental studies of the equilibrium angles of winter rape seeds, as well as various types of injured seeds, it has been found out that shrunken, injured seeds, compared to high-quality ones, have larger values of the equilibrium angles, and this confirms the possibility of their separation on the inclined separating plane moving in the electric field.

Under the condition of choosing the optimal value of the speed V_n and the intensity of the electric field E, it is possible to achieve the maximum difference in the values of the Δα_р equilibrium angles for individual seeds, and at the same time to achieve an effective mode of operation of the separator. The equilibrium angle α_р of the components of the seed mixture has a decisive influence on the design parameters (dimensions) of the working body (plane) of the electric separator.

THE USE OF TWO-PHASE OIL-VAPOR-GAS MIXTURES TO IMPROVE THE PERFORMANCE OF TRIBOSYSTEMS

Fri, 13 Oct 2023 00:00:00 +0300

The article investigates the viscosity-temperature and anti-wear properties of mineral and synthetic oils of the motor-transmission group under normal conditions and when giving these lubricants the properties of two-phase. Such properties are acquired by circulating selected lubricants through a tribomolecular generator, resulting in their physical-phase state becoming similar to such unstable media as oil-vapor-gas mixtures.

IMPROVING THE OPERATIONAL PROPERTIES OF CENTRIFUGAL CAST ROLLS WITH A WORKING LAYER OF CHROMIUM CAST IRON WITH MICROSTRUCTURE ASSESSMENT BY COMPUTER VISION

Fri, 13 Oct 2023 00:00:00 +0300

Based on the performed studies, it was found that the main criteria describing the quality and wear resistance of a roll with working layer of chromium cast iron are: proportion of residual austenite; degree of structure dispersion; chemical composition (ratios Cr/C, Ni/(Cr/C) and Cr/Ni); carbide phase; mechanical properties; voltage level regulated by heat treatment according to Hc. To predict operational resistance, it is advisable to use models establishing the relationship between chemical composition, ratio of structural components, conditions of working layer formation, heat treatment parameters, mechanical and operational properties.

CORROSION AND MECHANICAL WEAR OF NITROGEN STEELS IN ACID ENVIRONMENTS

Tue, 10 Oct 2023 00:00:00 +0300

The work is devoted to the study of the tribological properties of steels and cast iron strengthened by anhydrous nitriding in a glow discharge operating in acidic environments. Electrochemical behavior, wear resistance and corrosion resistance of nitrided surfaces in technological acidic environments have not been sufficiently investigated. Without considering the influence of operational factors on wear conditions leads to premature failure of processing and food industry equipment. The results of the study of corrosion-mechanical wear of nitrided and non-nitrided steels (С20; С45; 37Cr4; 41CrAlMo7) in an acidic model environment are given. The dependences of the intensity of wear and the coefficient of friction on the pressure in the frictional contact and on the sliding, speed was obtained. Results were also obtained on the change in the ratio of corrosive and mechanical wear factors depending on the pressure and sliding speed. The analysis of the effect of the temperature of the surface layers on the tribological properties of nitrided samples operating in an acidic environment was carried out. The influence of temperature and sucrose on the intensity of destruction of surfaces was clarified. The obtained results make it possible to make the optimal selection of hardening modes and operating conditions of nitrided surfaces working in acidic production environments.

WEAR RESISTANCE OF NITRIDED STEEL IN DRY FRICTION

Fri, 13 Oct 2023 00:00:00 +0300

the wear resistance of nitrided steels in the dry mode of friction was studied. In contrast to experiments at the limit of friction, dry friction can be used for different steels at the same pressure value, which eliminates the problem of comparability of results and contributes to the objectivity of conclusions regarding the effectiveness of various modification processes.

EFFECT OF HYDROGEN SULFIDE ON CORROSION AND TRIBOCORROSION OF STEEL 07Cr16Ni6

Thu, 07 Dec 2023 00:00:00 +0200

the influence of hydrogen sulfide concentration (0…1500 mg/dm³) in chloride-acetate solution on corrosion processes, hydrogenation and corrosion-mechanical wear of 07Cr16Ni6 steel has been studied. Hydrogen sulfide in solution, regardless of concentration, significantly reduces the corrosion resistance of steel. The wear resistance of steel in solution at hydrogen sulfide concentrations 100…500 mg/dm³ do not change significantly, and it decreases by ~30% at the concentrations 1000…1500 mg/dm³. It is associated with hydrogenation of friction surface.

EFFECT OF MOLYBDENUM CONTENT ON THE STRUCTURE AND TRIBOLOGICAL PROPERTIES OF DIAMOND-LIKE CARBON FILMS

Mon, 11 Dec 2023 00:00:00 +0200

: Molybdenum doped amorphous diamond-like carbon thin films (Mo-DLC) were deposited on Si (100) substrates by magnetron sputtering. The graphite and the molybdenum cathode current were fixed at 1 A and 0.25 A, respectively. The deposition duration was 600 s, and the distance was 6 cm. During the deposition the Mo content was changed by increasing the opening of a shield mounted above the Mo target from 4 mm to 32 mm and at the end without shield. The elemental composition, surface morphology, structure, and friction forces of the films were investigated by energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (multimode 8 Bruker) and Raman spectroscopy. The EDS results indicated that the Mo content increased with the opening of the shield above the Mo target. Additionally, the Raman spectra of the films indicated that the sp² carbon sites fraction increased, and graphitization was induced. The average surface roughness R_a slightly increased from 1.3 to 2.7 nm with the rise of Mo content. The friction coefficient of the Mo doped DLC films depended on the structure and composition of the films.