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In this work, the Copper composites Cu-x wt. % B4C (x = 0, 5, 10, 15, 20) were fabricated for the metallurgical and mechanical property evaluation as per ASTM standards. The metallurgical characterization tests on the samples include x-ray diffraction, optical microscopy, and scanning electron microscopy with EDX. Further, pin-on-disc apparatus was used to investigate the tribological behavior of composite specimens. An SEM micrograph of the worn surface and wear debris, along with the Gwyddion software, has been used to discuss the wear mechanisms in detail. The Artificial Neural Networks (ANN) classifier model is also constructed to describe the wear behavior in more detail. The experimental results inferred that the addition of Boron carbide particles has enhanced the Copper's corrosion resistance in a 1 M HCl electrolyte solution from 30.34% to 74.2%, 75.08%, and 83.29% with B and C ions. Also, it significantly enhance the mechanical and tribological characteristics considerably. KEY WORDS: Powder metallurgy, Cu-B4C, Gwyddion, Wear, Artificial Neural Network Bull. Chem. Soc. Ethiop. 2023, 37(4), 959-972. DOI: https://dx.doi.org/10.4314/bcse.v37i4.12 &nbsp

Solenoid operated valves (SOVs) are critical components in many industrial applications. There has been a continuing interest in the industry to have robust condition monitoring, prognostics and health management tools to support the condition based maintenance and predictive maintenance program for such valves. For critical assets like SOVs, it is of paramount interest to understand why a component might be declared as defective. In such a situation, a first principle-model based approach will always be preferred to a purely data-driven approach, because of its inherent interpretability. Furthermore, first principle-models typically have less free parameters than their data driven counterparts and will require less data to identify their parameters. In this paper, we present the improvement of a first-principle model of alternating current (AC) powered SOVs taking into account two important degradation effects. Using this model, we show that the state of degradation can be estimated from current and input voltage measurement signals on the solenoids. Our method is validated using data from an accelerated life test campaign on 48 identical AC-powered SOVs.

The modification of ceramic PEO coatings developed for friction units is in trend of modern research aimed at the improvement of friction and wear. This study presents ceramic coatings formed on AlZn5.5MgCu aluminum alloy by microarc oxidation (PEO) in a one-stage technological process with inclusions of Al-Cu-Fe quasi-crystals. The technology of rubbing quasi-crystals into the surface of the coating during final polishing was also used. Friction and wear tests, followed by analysis of the surface and cross-sections by SEM microscopy, showed that quasicrystals affect the coating structure and frictional characteristics. The addition of a small amount of modifier to the electrolyte (0.5 percent), as well as rubbing-in technology, can reduce the coefficient of friction (up to 16 percent) and wear rate (up to 43 times) compared to pure ceramic coatings. More modifier provides a negative result.

To improve the reliability and service life of thrust cylindrical roller bearings (TCRBs), the effects of single/compound pit texture on tribological properties and on friction-induced vibration and noise were studied. Laser marking equipment was used to create compound pit texture on a shaft washer. A universal friction and wear test rig was used to measure the friction force, vibration acceleration, and noise signals of TCRBs. The differences between the single/composite pit-textured and non-textured surfaces were studied in terms of the friction, wear, and vibration noise properties. The results revealed that the friction force and wear loss of the single/composite pit-textured surface were markedly lower than those of the non-textured surface. Compared to non-textured surface bearings, the friction force and wear loss for textured surface bearings were reduced by 39.6 % and 59.6 %, respectively, when the diameter, depth, and area density of the pit were 300 μm, 10 μm, and 10 %, respectively. The single/composite pit-textured surface exhibited good potential for vibration absorption and noise suppression. It could effectively interfere with the self-excited vibration of the TCRBs friction pair system, thereby reducing the degree of vibration noise of the TCRBs.

Today's surface modification methods include friction stir processing (FSP). using a combination of heat generated by the friction between the tool and the workpiece, intense plastic deformation, and stirring to mix the matrix material. To create a consistent and dense microstructure, the FSP continuously improves the material's surface characteristics. In addition, this unique method enables the creation of surface material matrix composites by incorporating various reinforcement particles (MMC). The importance of various types of reinforcing particles during FSP and their effects on surface properties like hardness, tensile strength, and wear behaviors have recently been the subject of a lot of research. Under various applied weights, sliding distances, and sliding velocities, the manufactured copper-cerium oxide surface composite was put through a sliding wear test. The FSP-ed surface composites had the lowest wear rate of 0.0039 mm3/N-m, and SEM analysis shows that the delamination layer and peeled-off behavior were seen on the worn-out surfaces.

When lubrication of rolling bearings with oil or grease is not possible, for example because the lubricant evaporates in vacuum, solid lubrication by multiwall carbon nanotubes (MWCNT) is a viable alternative. To understand the mechanisms underlying MWCNT lubrication of highly loaded contacts, we combine an experimental approach with large-scale molecular dynamics (MD) simulations. Tribometry is performed on ground iron plates coated with two different types of MWCNTs by electrophoretic deposition. Although structural differences in the MWCNT materials result in slightly different running-in behavior, most of the tests converge to a steady-state coefficient of friction of 0.18. The resulting wear tracks and tribolayers are subjected to structural and chemical characterization and suggest a tribo-induced phase transformation resulting in tribolayers that consist of MWCNT fragments, iron oxide, and iron carbide nanoparticles embedded in an amorphous carbon matrix. Covalent bonding of the tribolayer to the iron surface and low carbon transfer to the alumina counter body indicate sliding at the tribolayer/ball interface as the dominant mechanism underlying MWCNT solid lubrication. MD simulations of nascent a-C tribofilms lubricated by MWCNT bundles and stacks of crossed MWCNTs reveal two different sliding regimes: a low-load regime that leaves the MWCNTs intact and a high-load regime with partial collapse of the tube structure and formation of a-C regions. The critical load for this transition increases with the filling ratio of the MWCNT and the packing density of the stacks. The former determines the stability of the MWCNT, while the latter controls the local stresses at the MWCNT crossings. For both MWCNT materials, the high-load regime is predicted for the experimental loads. This is confirmed by a remarkable agreement between transmission electron microscopy (TEM) and atomistic simulation images. Based on the findings of this work, a multistep lubrication mechanism is formulated for MWCNT coatings rubbing against alumina on an iron substrate.

In this study, two high chromium cast irons (HCCI) with different chromium content (15%Cr and 25%Cr), in as-cast and annealed conditions (heat-treated, HT), were tested to determine the erosion wear behavior of these alloys. Erosion tests were done using a gas blast sand facility with high erodent particle velocity (90 m/s) and high erodent feed rate, at an impact angle of 45°, which represents conditions similar to service conditions of some components of thermal power plants using pulverized high mineral content coals. To identify erosion mechanisms, microstructural characterization was done by a scanning electron microscope on samples before and after erosion tests. Identification of microstructural phases was done by X-ray diffraction analysis. The main results of the tests shown in this paper indicate that matrix plastic deformation and distribution of carbide phase have a significant contribution to erosion resistance of HCCI alloys in severe erosion service conditions.

In this experimental research, an attempt is made to develop Al2214-B4Cp composite materials with reinforcement of micro boron carbide (B4Cp) (viz. 0, 1.5, 3, 4.5, and 6 wt.%) by using a novel liquid metallurgical stir casting technique with modified bottom pouring facilities and studying the microstructure, physical, mechanical, and dry sliding wear resistance responses. The microstructure of Al2214-B4Cp composite samples with varied boron carbide weight percentages was examined under an electronic scanning microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) device. The physical characteristics like density and porosity, mechanical strength, such as micro and macro hardness, yield and ultimate tensile strength, and sliding wear response were examined under variable experimental conditions. The experimental results of the Al2214-B4Cp composite revealed a decreased specific density with an increased weight percentage of boron carbide (B4Cp) particulate in the matrix and a homogeneous distribution of reinforced micro boron carbide (B4Cp) particles in the Al2214 matrix. There was an appreciable improvement in mechanical properties and wear strength in composite materials as compared to an unreinforced aluminium alloy.

A wear test in a used motor oil sliding environment was performed on Al-based automotive alloys with Silicon doped in various levels. Where a pin-on-disc wear testing equipment was used at a normal pressure of 1.53 MPa and a sliding speed of 0.51 m/s, kept constant. For comparison of the wear performance, dry and fresh motor oil sliding environments were also considered. The results showed that as silicon content was increased in the alloys, the wear rate decreased up to the eutectic composition, followed by an increase for all the environments. It was mainly for higher levels of Si-rich intermetallic Mg2Si precipitates in the α-aluminum matrix and made the alloys’ strength superior, in addition to increased wear resistance. In the post eutectic composition, primary silicon particles which are coarse and polyhedral appeared weakening the matrix. The coefficient of friction also decreased because of the higher hardness and the Si particles' employment as solid lubricants. In a dry environment, the wear rate and friction coefficient were much greater for their direct contact but lower under motor oil due to the reduced roughness caused by the sealing effects of the contact surfaces. Conversely, in oil environment, the opposite phenomenon was observed where a higher coefficient of friction was added to the alloy because the oil formed a thin film working as a lubricant between the contact surfaces which controlled the wear properties. Used oil demonstrates some degree of higher wear rate along with friction coefficient due to heavy and harmful chemical compounds in it. Examined by optical microscopy and SEM analysis, worn surfaces have shown that Si added alloy improved wear resistance through mild and smooth abrasive grooves filled with oxides in dry sliding conditions. In case of oil sliding environment smooth surfaces are created by the resistance of the oil film to the direct contact between the surfaces.

In this study, the long-term endurance tests were carried out in a diesel engine that used diesel and 90% diesel + 10% bioethanol fuels. The spray and temperature distributions of two different fuels in the AVL FIRE program also were examined. Tribological and morphological analysis of piston rings were investigated in a single-cylinder direct injection diesel engine using two different fuel types. The test engine used two different fuel types and was operated for approximately 110 hours under part engine load. Renewed rings in each fuelled engine operation were analyzed at Energy Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscope (SEM). Results were also compared with the non-worked piston ring. Analysis results saw that abrasive wear was more intense on the first rings at both fuel types. Examining the effect of biofuels on engine wears, short wear lines were found at engine rings using diesel/bioethanol blend fuel compared to diesel fuel. It was being determined that this situation was a result of combustion parameters (such as pressure, and temperature) created with the different fuels used in diesel engines. As a result, that bioethanol has a content of low carbon (C) compared to diesel fuel, making a positive contribution to the reduction of ring wear.

In this article, oil obtained from vegetable was used to lubricate a single-cylinder 2-stroke gasoline engine as lubricating oil, and tribological function of the obtained oil was investigated. To investigate the tribological functions of the lubricating oils, a 2-stroke single-cylinder gasoline engine was used. For mineral oil and hazelnut oil, the test engine was run for 100 hours for each one and were used to lubricate in the test engine as lubricating oils. Samples were prepared for the aim of the determining the wear on the cylinder surface, and also EDS (Energy Dispersive Spectrograph) analysis were obtained. The results of the analyses showed that, the wear on the cylinder surface were increased in the studies using hazelnut oil and the C content of the cylinder sample increased compared to the study with mineral oil. Al element was detected in the cylinder sample in the hazelnut study, that the reason for this, is the transport of the Al element during the friction event in the piston material to the cylinder surface.

In recent years, the tribological investigations have been focused on dispersing additives into the oil lubricants to improve their friction and wear properties. Microhardness measurements of the samples made from heat treated hot work tool steel were carried out in this study. The wear and friction behaviour of the samples were investigated under dry condition, base oil and 5%, 10%, 15%, 20% and 25% wt. graphite as oil additive. Wear tests were carried out by means of a ball-on-disc test configuration. Average friction coefficients and wear scar related wear rates were calculated. The morphology of the worn surfaces were analyzed by optical microscopy and scanning electron microscopy (SEM). The study leads to the conclusion that addition of graphite particles improved the wear and friction properties of the lubricant. 5% graphite dispersed oil additive exhibited the best tribological performance in the tests., Son yıllarda tribolojik araştırmalar yağlara katkılar ekleyerek onların sürtünme ve aşınma özelliklerini iyileştirmek üzerine yoğunlaşmıştır. Bu çalışmada, ısıl işlem uygulanmış sıcak iş takım çeliği malzemeden numunelerin kuru koşul, katkısız yağ ve ağırlıkça %5, %10, %15, %20 ve %25 grafit katkılı yağlarda aşınma ve sürtünme özellikleri incelenmiştir. Aşınma deneyleri ball-on-disc deney düzeneği ile gerçekleştirilmiştir. Ortalama sürtünme katsayıları ve aşınma izlerine bağlı olarak aşınma oranları hesaplanmıştır. Mikrosertlik ölçümleri yapılan numunelerin optik mikroskop ve taramalı elektron mikroskobu (SEM) ile aşınan yüzeylerinin mikroyapı analizleri yapılmıştır. Çalışmada sonuç olarak, grafit partiküllerinin yağın aşınma ve sürtünme özelliklerini iyileştirdiği görülmüştür. Deneylerde en iyi tribolojik performansı %5 grafit katkılı yağ sergilemiştir.

Roughness, defined as unevenness of material surfaces, plays an important role in determining how engineering components or natural objects interact with other bodies and their environment. The emergence of fractal roughness on natural and engineered surfaces across a range of length scales suggests the existence of common processes and mechanisms for nucleation and evolution of roughness. In this article, we review recent advances in understanding the origins of roughness and topography evolution on natural and engineered surfaces and their connection with subsurface deformation mechanisms. Directions for future research toward understanding the origins of roughness on solid surfaces are discussed.

Additive manufacturing (AM) being an integral component of the production offers a wide variety of applications in the production of different components. The medical industry after the introduction of Additive Manufacturing has resulted in several advancements. The production of intricate patient-specific implants is one of such advancements which greatly assist a surgeon during a surgery. Orthopedic implants apart from possessing good mechanical strength are also expected to exhibit good tribological and corrosion behavior. As a result, the development of various orthopaedic implants and tools has become simple with the use of additive manufacturing.In the current paper an effort has been made to discuss actual scientific knowledge on the tribo-corrosive behavior of additive manufactured parts for orthopedic applications. Different studies dealing with the mechanisms of lubrication and friction in synovial joints have also been considered. A special focus has also been laid down to study the corrosive effect of implants on the human body. A section dedicated to texturing of orthopedic implants has also been provided. The paper further elaborates the different research challenges and issues related to the use of additive manufacturing for the production of optimized orthopedic implants.The study revealed that additive manufacturing has greatly aided in the manufacture of different orthopaedic implants with enhanced properties. However, a detailed study of the effect of processes like friction, wear, lubrication and corrosion in these implants needs to be done. The performance of these implants in the presence of various synovial fluids also needs to be addressed. However, the lack of more biocompatible materials, scalability and cost issues hinder the widespread use of AM in the different orthopaedic applications.

Protective coatings can prolong the lifespan of engineering components. Electroless Ni-P coating is a very hard coating with high corrosion resistance, but low toughness. The addition of NiTi nanoparticles into the coating has shown the potential to increase the toughness of electroless Ni-P and could expand its usability as a protective coating for more applications. However, the study of the tribological behaviour and wear mechanisms of Ni-P-NiTi composite coating has been minimal. Furthermore, there is no studies on the effect of coating thickness on monolithic and composite electroless Ni-P coating wear behaviour. The wear rates of each coating were found by measuring the volume loss form multi-pass wear tests. The wear tracks were examine using a confocal microscope to observe the wear mechanisms. Each sample was tested using a spherical indenter and sharp indenter. It was found that the NiTi nanoparticle addition displayed toughening mechanisms and did improve the coating’s wear resistance. The 9 μm thick Ni-P-NiTi coating had less cracking and more uniform wear than the 9 μm thick Ni-P coating. For both the monolithic and composite coatings, their thicker version had higher wear resistance than their thinner counterpart. This was explained by the often observed trend in coatings where it has higher tensile stress near the substrate interface, which decreases and becomes compressive as thickness increases. Overall, the 9 μm thick Ni-P-NiTi coating had the highest wear resistance out of all the coatings tested.

The paper presents tribological tests of selected materials used as liners in a composite hydraulic cylinder. Three coating materials were used for the analysis: Sika F180 polyurethane, Huntsman Araldite LY1564 with Aradur 3487 amine hardener and Bezlona 1111 Super Metal. In addition, uncoated carbon epoxy laminate (CFRP) samples were used as reference material. The instantaneous course of the friction force, its maximum and average value, were the analysed parameters. Ball-on-disk tests were performed on a specialised tester that allows, among other things, to control the operating conditions (clamping force, operating temperature, speed, friction path) and measurement of the instantaneous value of the friction force. After these tests, the friction paths were observed using a Leica DCM8 contactless profilometer with an EPI 20x lens. The amount of energy dissipated due to friction was also determined. The conducted tests and comparative analyses allowed to conclude that the F180 material is the most desirable in terms of tribological properties.

In this study, a new design has been developed for towing hook dies used in hot forging processes. For this objective, analysis studies were carried out with different process parameters and methods for new designs in dies for both hot forging process and product. After the analysis, the die designs were determined that produced the prototype products at the optimum speed, efficiency and quality. While designing a special die for hot forging operation, a new die design has been developed in which both processes can be performed using a single die with two stages, pre-shape and final shape. Compared to the dies studied for hook groups in the literature and our old dies currently being worked, it is aimed to eliminate the errors caused by the inability to calibrate the final shape such as early wear, short die life, burr residue formation. Such a technics specific to the part as specific to the towing hook was performed for the first time, and with the die design developed by comparing the results of analysis studies, field trials and prototype studies in the Q-Form simulation program, the production of towing hook at optimum efficiency was achieved., Bu çalışmada sıcak dövme işlemlerinde kullanılan çeki demiri kalıplarına yeni bir tasarım geliştirilmiştir. Bu amaçla hem sıcak dövme prosesine hem de ürüne dair kalıplardaki yeni tasarımlar için, farklı proses parametreleri ve yöntemlerle analiz çalışmaları yapılmıştır. Analizler sonrasında prototip imalatları yapılmış en optimum hızda, verimlilikte ve kalitede ürün sonucu veren kalıp dizaynları belirlenmiştir. Sıcak dövme operasyonuna özel kalıp tasarımı yapılırken ön şekil-son şekil olmak üzere iki aşamalı tek bir kalıp kullanılarak iki işlemin de gerçekleştirilebildiği yeni bir kalıp dizaynı geliştirilmiştir. Literatürde kanca grupları için çalışılan kalıplara ve mevcutta çalışılan eski kalıplarımıza kıyasla erken aşınma, kısa kalıp ömrü, sakal oluşumu gibi son şeklin kalibre edilememesinden doğan hataların giderilmesi amaçlanmıştır. Çeki demiri özelinde parçaya özel böyle bir uygulama ilk defa yapılmış, Q-Form simülasyon programında analiz çalışmaları, saha denemeleri ve prototip çalışmaları sonuçları kıyaslanarak geliştirilen kalıp dizaynıyla optimum verimde çeki demiri üretimi sağlanmıştır.

AISI 304L steel is widely preferred in many fields such as pipe sector, biomedical and nu-clear industry due to its wear behavior and good ma-chinability. In this experimental study, temperature-dependent wear properties and worn surface struc-tures of AISI 304L steel were investigated. All tests were conducted by using pin-on-disc test equipment under unlubricated conditions. As ambient tempera-tures, 25°C, 50°C, 100°C, 150°C, and 200°C were se-lected. The results indicated that the main friction properties, wear mechanisms, and wear rate of the worn steel samples were significantly affected by al-tering the test temperatures. It was observed that the friction coefficient oscillated at lower temperatures, but this case was quite different at higher tempera-tures. Micro observations showed that mixed defor-mation characteristic dominated by adhesive wear was observed between 25°C and 150°C while abrasive wear became more effective between 150°C and 200°C. Moreover, wear rate and specific wear rate values increased until 150°C, then dropped as a result of changing the wear mechanism and contact surface structure. © 2022,Latin American Applied Research. All Rights Reserved.

One of the utmost important liquid lubrication regime is mixed lubrication regime as it occurs in almost all of the industrial machines & equipments. The most of the major impairments such as wear, micro pitting etc. happen in this lubrication regime. These days, mixed lubrication regime is the least tacit and so a lot of scope for the research is available in the same. Therefore, authors have focused themselves to investigate the effect on various tribological parameters i.e., friction & wear for sliding pair of EN31 & Brass with VG-46 & VG-32 hydraulic oils in mixed lubrication regime. This tribological pair is the most important and standard pair used in various industrial applications. VG-46 & VG-32 are also the most effective lubricants used in various industrial setups. This study will be helpful for various practical applications further because of its widely industrial applicability.

One of the most important variables that determine the braking performance of heavy-duty trucks is the high temperature increases in the brake components. In this study, the effects of high temperatures in brake lining compositions were investigated using thermogravimetric analysis (TGA). Furthermore, dynamometer tests and SEM analysis were performed. Three different compositions, which are called standard, fly ash and sisal fiber mixture, were compared with existing commercial heavy-duty truck brake lining. The thermal behavior of samples analyzed in TGA machine compared to the weight losses with increasing temperatures until 900 °C. Dynamometer tests which simulated the real part production and vehicle tests were realized in brake lining supplier. Finally, with the SEM analysis, both normal and worn surfaces were analyzed and reasons for wear surfaces were investigated. The findings suggest that there is a high potential in fly ash mixture to apply in commercial trucks applications which occurs at very high temperatures and is very suitable for environment and cost reduction points.

Two types of coatings, i.e., monolayer Ta and multilayer Ta/Ti/Zr/Ta coatings, were deposited on biomedical Ti6Al4V (TC4) alloy by magnetron sputtering to improve its performance. To evaluate the effect of the two coatings on the alloy properties, the microstructure, composition, mechanical and tribological properties, in vitro biocompatibility, and corrosion resistance were investigated. The results showed that α-Ta exists in the monolayer Ta coating, while α-Ta and β-Ta phases coexist in the multilayer Ta/Ti/Zr/Ta coating. The multilayer Ta/Ti/Zr/Ta coating possessed the highest hardness and the monolayer Ta coating had the lowest friction coefficient compared to the Ti6Al4V alloy. The friction and wear tests revealed that the anti-wear performance of the Ta coating is the best, followed by that of the Ta/Ti/Zr/Ta coating, while the anti-wear performance of TC4 alloy is relatively poor in comparison with the Ta and Ta/Ti/Zr/Ta coatings. The wear resistance of the multilayer Ta/Ti/Zr/Ta coating under low normal load is better than that under high load normal load. Finally, the in vitro and electrochemical corrosion tests showed that the Ta coating modification provides better biocompatibility and corrosion resistance than those of the uncoated Ti6Al4V alloy.

Fuel lubricity is an essential property that ensures the longevity end efficiency of diesel CI engines. Nanomaterials have been shown to have the potential to improve lubricity in many different lubricating substances, including fuels. Moreover, the combustion process has also been shown to improve with the introduction of nanomaterials. This study investigated a series of nanoparticles, including carbon nanoplates, carbon nanotubes, aluminum oxide, zinc oxide, and cerium oxide, as lubricity-enhancing additives for selected fuels. Conventional diesel fuel and rapeseed oil methyl ester, referred to as biodiesel, were chosen as base fuels for modification. The lubricity was evaluated according to the standard test method ASTM 6079 using the HFRR tribometer. The leading lubricity indicators were the wear scar diameter, wear volume, and coefficient of friction. In addition, the worn surface analysis was performed to elucidate the lubrication mechanism. The results show that the addition of nanoparticles can improve the lubricity of both investigated fuels. However, the effect differed among nanoparticles and fuels. In summary, carbon nanotubes could be a rational choice for both fuels. In addition, zinc oxide improved the lubricity of diesel fuel, while carbon nanoplatelets and aluminum oxide nanoparticles showed improvements in the lubricity of biodiesel.

Contamination in hydraulic systems is the cause of 70% of failures. This study highlights the performance degradation caused by solid particle contamination of hydraulic components: hydraulic gear pump, 4/3 valve, and orbital motor. Experimental durability tests of components with wear particles and test dust are used to investigate the effects of accelerated wear caused by these two types of contaminants. Results show that oil contaminated with wear particles reduces the volumetric efficiency of the gear pump by 18% and the hydraulic valve by only 0.8%, while oil contaminated with test dust reduces the efficiency of the pump by 76% and the hydraulic valve by 0.9%. This research provides insights for accelerating hydraulic component testing to improve system reliability and longevity.

Aluminum is a very commonly used material at present, and roughly half of the produced aluminum products undergo forming during manufacturing. Galling is a severe form of wear that occurs during sheet metal forming operations and is a common failure mode of materials in sliding contact; however, the causes and mechanisms of galling are poorly understood. In this work, sliding wear experiments were conducted to produce galling wear between a tool steel ball bearing and aluminum alloy Al5083, to study the relationship between the coefficient of friction, the lump growth on the tool and the scratch morphology. Whilst the characteristic friction regimes were observed, the characteristic damage (grooves running parallel to the scratch direction) was not observed. Instead, when galling was developed on the indenter, the scratch surface morphology displayed a series of peaks and grooves perpendicular to the scratch direction. It is likely that the difference in scratch morphology observed once galling was initiated is due to the lower hardness and reduced work hardening behavior of the Al5083 alloy, compared to the high strength steels previously examined in sheet metal forming applications. The evolution of the scratch morphology has been characterized in a novel way by investigating the distribution of the longitudinal cross-section profile height along the scratch length in relation to the three-stage friction regime observed. This showed that, as the galling wear progressed, the longitudinal cross-section profile height distribution shifts towards negative values, with a corresponding shift in the distribution of material transferred to the tool shifting to the positive. This indicates that, as the amount of material adhered to the indenter increased, the depth of the grooves on the scratch surface perpendicular to the sliding direction also increased.

This paper proposes a simplistic approach toward estimating incremental wear in a multi-contact scenario using a vibrational analysis approach and in turn goes a step forward to model its associated sound. Predicted wear depth and frictional sound are compared to the experimental values obtained using a standardized pin-on-disc tribometer setup affixed with a free-field microphone to capture air-borne noise. The results show good conformity between the proposed analytical model values and the standardized experiments, hence ensuing that within certain limitations, the proposed model and the intended approach can effectively be used as a good estimator of wear and its sound in a multi-contact scenario.

The paper investigates PcBN cutting tools of the BL group developed at the Institute of Superhard Materials, made with the addition of ceramic components TaN, TiC, TiN. Such materials are classified as ceramic-matrix composites (CMC). Thehardness of the new modifications of composites for cutting tool purposes ranged from 31,2 to 40,2 GPa. Experimental studies were carried out under the conditions of high-speed cutting of hardened steels ShKh15 and KhVG. The performance of superhard composites was studied based on the criterion of the absence of brittle destruction of the cutting edge of the tool, and the effectiveness of new composites based on the criterion of the minimum intensity of wear of the clearance face of the indexable inserts when machining with cutting modes corresponding to the conditions of finishing. High performance parameters – quality of the finish and minimum intensity of wear have been demonstrated by tools equipped with CMC, which contain a matrix formed by titanium carbide., У роботі досліджувалися розроблені в Інституті надтвердих матеріалів ім. В.М. Бакуля інструменти з надтвердих матеріалів на основі КНБ групи BL, виготовлені з додаванням керамічних компонентів TaN, TiC, TiN. Такі матеріали класифікуються як керамоматричні композити (КМК). Твердість нових модифікацій композитів інструментального призначення становила від 31,2 до 40,2 ГПа. Експериментальні дослідження проводилися в умовах високошвидкісного різання загартованих сталей ШХ15 та ХВГ. Вивчалася працездатність надтвердих композитів за критерієм відсутності крихкого руйнування різальної кромки інструменту та ефективність нових композитів за критерієм мінімальної інтенсивності зношування задньої поверхні різців під час різання з режимами, що відповідають умовам фінішної обробки. Високі експлуатаційні параметри – якість оброки та мінімальна інтенсивність зношування – були продемонстровані інструментами, що оснащені КМК, які містять матрицю, утворену карбідом титану.

This work is the result of a problem of premature development of rail corrugation found on a new metro line. As urgent solutions, a rail grinding was carried out and friction modifier started to be applied. Experimental corrugation measurements have been taken periodically in this line at 60 control points since 2018, and an extensive database has been collected since then. As a second stage, a computationally efficient new model has been developed to predict corrugation growth under different running conditions. The aim of this work has been to obtain feasible solutions to delay corrugation growth in metro type lines. The authors gratefully acknowledge financial support from the European Horizon 2020 Joint Technology Initiative Shift2Rail (IN2TRACK3) [101012456], from the Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO and MCI/AEI [PID2019-109483RB-I00], including funding by the FEDER-ERDF European Regional Development Fund, and from the Basque Government [IT1764-22, PRE_2021_2_0047, KK-2023/00029].

Contamination in hydraulic systems is the cause of 70% of failures. This study highlights the performance degradation caused by solid particle contamination of hydraulic components: hydraulic gear pump, 4/3 valve, and orbital motor. Experimental durability tests of components with wear particles and test dust are used to investigate the effects of accelerated wear caused by these two types of contaminants. Results show that oil contaminated with wear particles reduces the volumetric efficiency of the gear pump by 18% and the hydraulic valve by only 0.8%, while oil contaminated with test dust reduces the efficiency of the pump by 76% and the hydraulic valve by 0.9%. This research provides insights for accelerating hydraulic component testing to improve system reliability and longevity.

Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (γ′-Fe4N and/or ε-Fe2-3N) in improving the tribological and corrosion-resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behavior of a 5 μm thick γ′-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl-containing solution under various electrochemical conditions. The results show that at a cathodic potential of −700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the γ′-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of −200 (SCE), the γ′-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the γ′-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability to resist both mechanical wear and corrosion and to reduce wear–corrosion synergism.

The challenge of dysfunctional engineering components produced via additive manufacturing is a current global concern. This appears to stem from the relatively poor mechanical performances often exhibited by 3D-printers nozzles produced from brass. The current study investigated the feasibility of enhancing the wear and mechanical properties of 3D-printers nozzles using iron-millscale modified copper-zinc alloy as a viable alternative. The methodology entailed addition of varying weight percent of iron-millscale (IMS) into copper-zinc alloy aimed at significantly modifying its microstructure for desirable impact on the mechanical properties. The charges were melted in an induction furnace, cast in metal moulds and characterised for wear and mechanical properties. Results show that the formulation containing 6 wt. % IMS addition exhibited superior mechanical characteristics in terms of hardness (201.4 VHN), wear rate (0.69 cm2 x 10-6), wear resistance (934.9 cm-2 x 103) and modest impact energy (30.3 J). These results compare well with desirable wear and mechanical properties of high quality 3D printer nozzles. Contributions to this level of performances may have emanated from the refined microstructure showing homogeneously dispersed fine CuFe3Zn2 crystals. It is concluded that the developed alloy is a viable candidate material for 3D printer nozzle production.

This paper analyzes the phenomenon that conditions the durability and reliability of a type of dental bur based on the wear of the active part and with effect on its quality. For the experimental study, a conical-cylindrical dental bur and a sample dental material in cobalt–chromium alloy, cylindrical shape, tested on a specially made experimental installation were used. In this paper, the most significant parameter was considered (loss of mass, mw, through the wear of the active part of a tested dental bur), which highlights the studied wear phenomenon. This is useful for the establishment of the durability and reliability of the dental bur by the extension of the lifetime or even optimization of its operation. The wear phenomenon of the active part of dental bur is studied based on the results and experimental data obtained in the work process that was validated by interpolation and led to polynomial functions which approximate very well the dependent parameter, mw, considered in the experimental program. The results of the interpolation showed that in the first 11 h of work, the dental bur works with high efficiency (allow optimizing operation or offering new ideas for constructive solutions), after which it can be easily decommissioned; i.e., it should be replaced with a new one (establishing some possible criteria for replacing the used dental bur).

open access article Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (’-Fe4N and/or -Fe2-3N) in improving the tribological and corrosion resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behaviour of a 5 m thick ’-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl containing so-lution under various electrochemical conditions. The results show that at a cathodic potential of -700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the ’-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of -200 (SCE), the ’-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the ’-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability resist both mechanical wear and corrosion and to reduce wear-corrosion synergism.

False brinelling damage in rolling bearings can lead to reduced component lifetimes and increased noise emissions, adversely affecting machine performance. Therefore, minimizing or avoiding such damage is very important. Environmental or operating conditions that can lead to false brinelling damage often cannot be avoided. Alternatively, such damage can be significantly reduced with suitable lubricants. This study utilized a test method from the research project FVA 540 to examine the impact of the base oil viscosity and NLGI class of greases on false brinelling damage at different temperatures. The results showed a clear dependency between the base oil viscosity of greases and the extent of false brinelling damage. Two different thickeners (lithium hydroxystearate/diurea) and different base oil types (PAO/esters) were investigated for this purpose. The results indicate that temperature had a significant effect on the physical and rheological properties of greases and show the potential for reducing false brinelling damage through the selection of appropriate lubricants. These results provide valuable information to improve the performance and lifetime of rolling bearings in industrial settings.

Hybrid composite materials can successfully solve the problems of reliability, durability, and extended functionality of products, components, and details, which operate under conditions of multifactorial influences (temperature, force, and deformation). The authors have developed a hybrid composite high-entropy AlCoCrCuFeNi material and ceramic cBNCoMo(B4CCoMo) layer. The formation of hybrid composites was carried out using new technology. This technology includes high-energy machining, high-velocity oxygen-fuel spraying in a protective environment, high-temperature thermomechanical treatment, and heat treatment. The use of the developed technology made it possible to increase the adhesive strength of the composite layers from 68 to 192 MPa. The authors performed an assessment of the structural parameters of the composite layers. The assessment showed that the composite layers had a nanocrystalline structure. The research included mechanical tests of the hybrid composites Hastelloy X (NiCrFeMo)—AlCoCrCuFeNi—cBNCoMo and Hastelloy X (NiCrFeMo)—AlCoCrCuFeNi—B4CCoMo for cyclic durability (fatigue mechanical tests) and friction wear. The use of surface-layered materials AlCoCrCuFeNi—cBNCoMo and AlCoCrCuFeNi—B4CCoMo in the composition of hybrid composites significantly increased cyclic durability. The use of surface-layered materials in the composition of hybrid composites made it possible to reduce wear intensity. The test results show that the developed composites are promising for use in various industries (including oil and gas), where high strength and wear resistance of materials are required.

Electric vehicles can lead to accelerated tire wear, an inevitable phenomenon during tire usage that can affect the cornering characteristics determining handling stability. In order to simulate tire wear, a finite element model for tire wear was established using the UMESHMOTION subroutine and Arbitrary Lagrangian–Eulerian (ALE) adaptive meshing in ABAQUS, which is based on the Archard theory. The tire’s cornering characteristics were analyzed based on the obtained worn tire. The research results demonstrate that as the wear amount increases, the cornering stiffness and aligning stiffness of the tire also increase. When there are differences in wear on both tire shoulders with the same global wear, the change in cornering stiffness is not significant, while the aligning stiffness exhibits noticeable differences. To explain the above phenomenon, grounding characteristics were incorporated as mediator variables. The analysis results indicate that wear has an impact on the grounding characteristics. Additionally, statistically significant correlations exist between grounding parameters and cornering characteristics. In conclusion, wear affects the tire’s cornering characteristics by changing the grounding characteristics.

This study aimed to enhance the friction performance and controllable range of magnetorheological devices by investigating the impact of different materials on the tribological properties within a magnetorheological fluid (MRF) under the influence of a magnetic field. A novel friction-combined structure was proposed, consisting of a ferromagnetic metal base and a metal surface shell fabricated using 3D printing technology. The design offered several advantages: the ferromagnetic base significantly improved the magnetic field control range, the 3D-printed surface shell allowed easy replacement with different materials and textures, and it reduced both development and application costs. In this experimental study, composite samples consisting of metal 3D-printed surfaces and substrates made of different materials were used to evaluate the friction and wear characteristics of the MRF under different magnetic field conditions. Computer numerical control (CNC)-machined surfaces were also included for comparison. The results showed that the ferromagnetic matrix affected the magnetic field size and distribution of the energized coil, resulting in an increase in the friction coefficient, but also an increase in wear. Furthermore, the combination of 3D-printed surfaces with ferromagnetic substrates had a more pronounced effect on the friction coefficient compared to CNC-machined surfaces. Based on these findings, this research concluded that 3D-printed surfaces outperform CNC-machined surfaces in this specific environment. In addition, the proposed design, which combined ferromagnetic bases with 3D-printed surfaces, shows potential for improving the friction performance of friction components. The increase rate of friction coefficient from 0.1459 at no current to 0.2089 at 2.5A was 43.18%. This offers a novel application of 3D printing technology in magnetorheological devices.

This study aims to analyze tire wear particulate matter (TWP) from tread rubber with different formulations and to compare the concentration of TWP with different wear devices. The TWP generated during the abrasion of truck and bus radial (TBR) tires were examined, and the effect of using different types of rubber and carbon black (CB) were investigated. When natural rubber (NR) was solely used as the tire tread rubber material, there was a higher concentration of 5–10 µm TWP. However, when the tread formulation consisted of NR mixed with butadiene rubber, the TWP concentration decreased. Changing the type of CB also reduced the amount of TWP in the 2.5 µm size range. The TWP concentration in the specimens increased with increasing speed and vertical load. The TWP generated during the abrasion tests using wear testers and tire simulators exhibited similar trends. These findings suggest that modifying tire tread formulations can effectively control the distribution and amount of TWP generation.

This study focused on investigating the adhesion and tribological properties of niobium-doped titanium nitride (TiNbN) coatings deposited on D2 steel substrates at various substrate temperatures (Ts) under simulated cutting conditions. X-ray diffraction confirmed the presence of coatings with an FCC crystalline structure, where Nb substitutes Ti atoms in the TiN lattice. With increasing Ts, the lattice parameter decreased, and the crystallite material transitioned from flat-like to spherical shapes. Nanoindentation tests revealed an increase in hardness (H) with Ts, while a decrease in the elastic modulus (E) resulted in an improved elastic strain limit for failure (H/E) and plastic deformation resistance (H3/E2), thereby enhancing stiffness and contact elasticity. Adhesion analysis showed critical loads of ~50 N at Ts of 200 and 400 °C, and ~38 N at Ts of 600 °C. Cohesive failures were associated with lateral cracking, while adhesive failures were attributed to chipping spallation. The tribological behavior was evaluated using a pin-on-disk test, which indicated an increase in friction coefficients with Ts, although they remained lower than those of the substrate. Friction and wear were influenced by the surface morphology, facilitating the formation of abrasive particles. However, the absence of coating detachment in the wear tracks suggested that the films were capable of withstanding the load and wear.

Both erosive and abrasive wear are common in mechanical systems and moving components in industrial production. Once they occur in machine parts, the task of breakdown maintenance should be carried out, leading to high production costs. Previous research has shown that high-chromium cast iron (HCCI), a commonly used wear-resistant material, experiences repeated particle impacts that break up the chromium carbides (M7C3) on its surface, resulting in the formation of fine fracture carbides. It has been reported that erosion wear occurs progressively due to the shedding of protrusions caused by the plastic deformation of the material’s matrix. Thus, the erosion wear characteristics of a material are strongly affected by carbides, which come in various shapes and can affect resistance. This research examined the orientation of carbides on the microstructure and their effects on erosion and abrasion properties. The wear tests showed that 27 wt.% chromium content high-alloy cast irons showed the best wear resistance properties due to the coarse strips of M7C3 carbides that effectively suppressed wear propagation. Additionally, the M2C carbides crystallized around the M7C3 carbides which support the M7C3 carbide to reduce plastic deformation and carbide peel-out. Consequently, the wear resistance properties of this material are significantly improved.

The demanding material quality criteria in the automotive and aerospace industries have recently had an impact on the development of lightweight aluminium alloys. The choice and application of metal-matrix composites as structural materials in this context are known to offer a variety of benefits. These benefits include the ability to combine high elastic modulus, toughness, and impact resistance; minimum sensitivity to change in temperature or thermal shock; durability of the surface is good; moisture absorption leads to the potential issue while minimum exposure which leads to environmental degradation; and improved fabricability with conventional metalworking equipment. Aluminium metal matrix composites (AMMCs) are a potential material for advanced structural, aviation, aerospace, marine, and defence applications, as well as for the automotive sector and other related fields, due to their outstanding combination of qualities. The stir casting procedure is used to create an aluminium metal matrix composite (AMMC), which is the most efficient way to do so. In this study, the aluminium alloy 7075 is strengthened using neem leaf powder and SiC. The Vickers hardness examination method is used to govern the hardness of hybrid composites. Eventually, the mechanical and tribological properties of the composites were assessed, and their relationship to the composites' matching microstructure and wear was addressed. &nbsp

The construction and practical use of complexes of mechanical reliability models creates real prerequisites for the transition to resource design of assembly units and aggregates of mobile machines. Therefore, the article solves the tasks of building complexes of inverted stochastic models, which provide the possibility of joint statistical analysis of heterogeneous information about reliability in cases of types of destruction typical for machine elements: during wear and fatigue. A fairly complete and convenient method for solving many problems of mechanical reliability is given for describing a non-stationary monotonic degradation process, which consists in the task of the type of its function or the density of distribution in time segments with parameters that are deterministic monotonic functions of time or working time in load cycles. Such functions should be perceived as parametric. Schemes of models of two main types of degradation processes in machine elements are also given: monotonically increasing, associated with wear and monotonically decreasing, due to fatigue failure. At the same time, the process corresponding to wear is formed by random realizations of a change in the failure parameter over time, and the process characterizing fatigue failure is formed by a set of random individual fatigue curves that depend on cyclic durability. The considered theoretical analysis of the main degradation processes that determine the mechanical reliability of machine elements made it possible to develop a universal approach to building complexes of stochastic reliability models, which provides the possibility of joint statistical evaluation of model parameters for processes caused by wear and tear and fatigue destruction. The practical use of the proposed complexes of mechanical reliability models is expedient both for accelerated assessment and for predicting reliability at the stage of resource design of elements of mobile machines., У статті наводиться досить зручний при вирішенні багатьох завдань механічної надійності спосіб опису нестаціонарного монотонного деградаційного процесу, що полягає в задаванні виду його функції або щільності розподілу в перерізах часу з параметрами – детермінованими монотонними функціями часу або напрацювання в циклах навантаження. Розглянутий теоретичний аналіз основних деградаційних процесів, що визначають механічну надійність елементів машин, дав змогу розробити універсальний підхід до побудови комплексу стохастичних моделей надійності, що забезпечує можливість спільного статистичного оцінювання параметрів моделей для процесів, зумовлених зношуванням і втомним руйнуванням. Практичне використання пропонованого комплексу моделей механічної надійності є доцільним як при прискореному оцінюванні, так і прогнозуванні надійності на стадії ресурсного проєктування елементів мобільних машин.

Cereal straw is a biomaterial with great potential: about 144 million tons of biomass are grown annually in Europe. For any use of straw (fertilizer, biofuel, etc.), efficient chopping technology, i.e., the reliable and efficient operation of mobile or stationary choppers, is the key factor for further success. Since most of the straw is chopped at harvest time, the subject of the study is the wear of the combine’s chopping knives. Six blades of different materials and designs were tested under realistic conditions during wheat and rapeseed harvesting on 180 ha. The influence of hardness, composition, cutting edge angle, and position in the chopper on knife wear was analyzed. The study showed that the blades with the highest cutting edge hardness (568 ± 11 HV) and the lowest cutting edge angle (20.9°) had the lowest wear. The highest hardness of the induction hardened knives was due to the 0.42% carbon content of the steel. The study confirmed that wear was inversely proportional to the hardness of the cutting edge (the harder the cutting edge, the lower the wear) and directly proportional to the angle of the cutting edge (the higher the angle, the greater the wear). The SEM study showed that part of the tooth surface of the blades was covered by permanent deposits of the material to be shredded. This wear was not caused by the interaction between straw and blade but by microabrasive particles that contaminated the straw.

Wear is a tremendously important phenomenon, which takes place on the surfaces of two solids in contact under cyclic loads and constitutes one of the most-significant ways of failure for mechanical elements. However, it is not the only source of failure in contacting solids. The subsurface stresses should also be considered, due to the fatigue and crack initiation problems. Nevertheless, these stresses (i.e., their maximum values and distributions) evolve with the solids’ surface wear (i.e., with the load cycles) and also depend on the friction intensity. Therefore, their evolution should be properly computed to predict failures in mechanical elements under wear conditions. This work focused on the study of the evolution of the surface wear and the subsurface stress distributions generated—in an elastic half-space—by a cylindrical flat-ended punch, under cyclic indentation loading (i.e., radial fretting wear conditions). Based on a numerical scheme recently presented by the authors, this is the first time that, for this contact problem, the surface wear and subsurface stress distribution (i.e., maximum value and its location)—and its evolution—were simultaneously analyzed when orthotropic friction and fretting wear conditions were considered. The studies presented in this work were developed for purely elastic contact assumptions.

A progressive type of tungsten-doped DLC coating was applied to a quenched and tempered 100Cr6 steel with the aim to improve the wear and corrosion properties in simulated seawater conditions and to compare the performance to conventional DLC coating. Tungsten doping caused a shift of the corrosion potential (Ecorr) to a lower negative value of −172 mV, while the conventional DLC exhibited an Ecorr of −477 mV. In dry conditions, the W-DLC coefficient of friction is slightly higher than that of the conventional DLC (0.187 for the W-DLC vs. 0.137 for the DLC), but in cases of a saltwater environment, this difference becomes almost negligible (0.105 for the W-DLC vs. 0.076 for the DLC). The conventional DLC coating also started to show marks of deterioration when exposed to a combination of wear in a corrosive environment, while the W-DLC layer still maintained its integrity.

This research was carried out with the aim of obtaining appropriate principles for describing the influence of working parameters and the aggressive action of an acidic medium on the wear and corrosion resistance of martensitic stainless steels. Tribological tests were performed on induction-hardened surfaces of stainless steels X20Cr13 and X17CrNi16-2 under combined wear conditions at a load of 100 to 300 N and a rotation speed of 382 to 754 min−1. The wear test was carried out on a tribometer with the use of an aggressive medium in the chamber. After each wear cycle on the tribometer, the samples were exposed to corrosion action in a corrosion test bath. Analysis of variance revealed a significant influence of rotation speed and load due to wear on the tribometer. Testing the difference in the mass loss values of the samples due to corrosion using the Mann–Whitney U test did not show a significant effect of corrosion. Steel X20Cr13 showed greater resistance to combined wear, which had a 27% lower wear intensity compared to steel X17CrNi16-2. The increase in wear resistance of X20Cr13 steel can be attributed to the higher surface hardness achieved and the effective depth of hardening. The mentioned resistance is the result of the creation of a martensitic surface layer with dispersed carbides, which increases the resistance to abrasion, dynamic durability, and fatigue of the surface of the protective layer.

Gear wear is unavoidable and results in vibrations and decreased performance in a planetary gear system. In this work, the wear phenomenon of the gear teeth surface and the dynamic responses of the planetary gear mechanism are investigated through a computational methodology. Dynamic responses are presented by considering the dynamic wear effects. First, the model of the planetary gear mechanism dynamics is established by considering the nonlinear stiffness and friction of gear surfaces. The dynamic wear model of the gear is then established based on Archard’s wear model. Further, the coupling between the dynamics and wear characteristics of the planetary gear mechanism is presented by considering the dynamic wear effects. Finally, a numerical investigation is conducted. The simulation results reveal severe wear between the sun and planet gears. The wear depth and meshing vibration responses exhibit prominent nonlinear characteristics. The low-order resonance of the meshing frequency becomes more marked as the mesh times and wear increase.

Cu matrix composites benefit from the high electrical and thermal conductivities of Cu and the mechanical wear/erosion resistance of hard reinforcement. In this study, an attempt has been made to determine the effect of the addition of reinforcement B4C in Cu-Ni-Sn. The B4C is reinforced to form a hybrid Cu matrix composite with powder metallurgy technique. The hybrid composites are obtained by milling, blending, and compacting the powders to obtain a fine grain-sized particle without aggregation. The grain size and particle nature were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques, respectively. The microstructure, density, hardness, and wear rate of the composites were studied. The pin-on-disc method is equipped to study the wear behaviour and coefficient of friction. The sintered density of the prepared Cu-15%Ni is 98.25 %, Cu-8%Sn is 98.20 %, Cu-15%Ni-8%Sn is 98.10 % and Cu-15%Ni-8%Sn-2%B4C is 95.26 % and lower specific wear rate has been recorded for Cu-15Ni-8Sn-2B4C 121×10-6 mm3/(Nm) and the addition of reinforcement B4C in Cu-Ni-Sn displays remarkable changes in wear rate and friction coefficient.

Sodobne tehnologije obdelave materialov se vse bolj premikajo v smeri zahtevnih pogojev odrezovanja: Ti pogoji zahtevajo, da so rezalna orodja prekrita z učinkovitimi zaščitnimi prevlekami. Taka prevleka mora prenesti visoke termomehanske obremenitve in biti obstojna proti degradaciji v zahtevnih okoljih. V ta namen se že vrsto let uporabljajo trde zaščitne prevleke na osnovi nitridov prehodnih kovin, saj nudijo visoko zaščito orodja pred velikimi obremenitvami, kot sta povišana temperatura ter tlak. Pred uporabo v proizvodnji mora vsak proces razvoja novih prevlek vključiti tudi tribološke teste pri temperaturah, ki so relevantne za dano aplikacijo. Obraba predstavlja progresivno poškodbo kontaktnih površin, ki vključuje izgubo materiala. Pojavi se na površinah, ki so izpostavljene obremenitvam in hkrati medsebojnemu relativnemu gibanju. V magistrskem delu sem za merjenje koeficienta trenja uporabil visokotemperaturni tribometer, s pomočjo katerega sem lahko preračunal obrabo prevleke TiAlN pri povišani temperaturi. Tribološka karakterizacija prevlek je sestavljena iz množice triboloških testov različnih dolžin pri različnih temperaturah. Tako sem lahko določil, kdaj v tribološkem testu pride do največje obrabe in kako se trenje ter obraba spreminjata od začetnega kontakta pa do popolne izrabe prevleke. Po vsakem opravljenem tribološkem testu sem z uporabo profilometra izmeril obrabno kaloto ter določil obrabo. Posamezne vzorce sem analiziral tudi z uporabo vrstičnega elektronskega mikroskopa ter EDS-analizo. Zanimalo me je, kakšen je vpliv temperature na tribološke lastnosti prevleke TiAlN. V prvem delu naloge so predstavljene teoretične osnove, ki jim sledi eksperimentalni del in opis ter razlaga rezultatov. Modern material processing technologies are moving towards increasingly challenging cutting conditions. These conditions require cutting tools to be covered with effective protective coatings. Such coatings must withstand high thermomechanical loads and be persistent against degradation in demanding environments. For this purpose, protective coatings based on transitional metal nitrides have been used for many years, as they offer high protection of the tool against high loads such as elevated temperature and pressure. Before being used in production, each process of developing new coatings must also include tribological tests at temperatures that are relevant for daily application of the coating. Wear represents progressive damage to the contact surface, which also involves loss of coat material. It occurs on surfaces that are exposed to stresses (forces) and, at the same time, the relative movement between them. In my master's thesis, I measured the coefficient of friction on a high temperature tribometer which was used to calculate the wear for the AlTiN coating at higher temperatures. The tribological characterization of coatings consists of a set of tribological tests of different lengths at different temperatures. This was how I was able to determine when during the tribological test maximum wear occurred and how friction and wear changed from initial contact to the failure of the coating. After each tribological test, I measured the wear route using a profilometer and determined the wear. I also analyzed individual samples using a line electron microscope and EDS-analysis. I was interested in the effect of temperature on the tribological properties of the AlTiN coating. In the first part of the assignment, the theoretical foundations are presented, followed by the experimental part, and the description and interpretation of the results.

The analysis of antifriction and antiwear additives to lubricants has been carried out and the mechanisms of formation of protective films on tribocombination elements have been considered. An increase in the antifriction and antiwear characteristics of lubricants due to their additional modification with graphite, molybdenum disulfide, fullerenes, nanotubes or a repair composition has been established. The mechanism for increasing the efficiency of lubricants with friction modifiers is to create a protective surface layer in the process of tribosystem self-organization during friction. It has been established that by empirical analysis it is possible to choose the optimal concentration of the repair and restoration compound RVS, the addition of which to the gear oil provides an increase wear resistance of steel under rolling conditions with slippage. Reducing the wear of contact surfaces is facilitated by mechanical chemical processes that manifest themselves during structural adaptability of finely dispersed components of the geomodifier friction RVS, boundary lubricating films and metal surface layers at friction under dynamic loading conditions. For the main indicators providing an increase in the wear resistance of friction pairs are microhardness of metal surface layers and its gradient depth distribution, microgeometry of the surface layer, formed during friction, and the formation of boundary lubricating layers on friction-activated contact surfaces. These processes are a manifestation of structural adaptability structural materials under study, the consequence of which is qualitative and quantitative change in the microgeometry of surfaces friction. Fullerenes and nanotubes are elementary objects of nanotechnologies, on the basis of any possible macro-objects, which may be of practical importance, - materials and outbuildings. The potential of using these structures (especially nanotubes) exceeds potential of other nanostructures. Проведено аналіз антифрикційних та протизношувальних добавок до мастильних матеріалів та розглянуто механізми утворення захисних плівок на елементах трибосполучення.

The article considers the efficiency of applying electric spark coatings with the aim of studying the effective influence on the tribological properties of eutectic alloys. Friction and wear tests of electrospark coatings made of the developed eutectic alloy on a steel substrate were performed. In order to compare the effectiveness of the influence on the tribotechnical properties of eutectic alloys, both the coatings in the initial state and the coatings annealed under two different modes were tested. Based on the results of the study of the chemical composition of the films formed in the process of friction, regularities were established by qualitative assessment. The dependences of tribotechnical properties for the initial and heat-treated coatings were determined. These studies indicate the feasibility of using electrospark coatings for different friction conditions. Розглянуто питання доцільності нанесення електроіскрових покриттів з метою дослідження ефективного впливу на трибологічні властивості евтектичних сплавів. Проведено випробування на тертя і зношування електроіскрових покриттів з розробленого евтектичного сплаву на підкладці зі сталі. З метою порівняння ефективності впливу на триботехнічні властивості евтектичних сплавів випробувалися як покриття у початковому стані, так і покриття, що були відпалені за двома різними режимами. За результатами дослідження хімічного складу утворених в процесі тертя плівок було встановлені закономірності за якісною оцінкою. Встановлено залежності триботехнічних властивостей для вихідних і термооброблених покриттів. Проведені дослідження свідчать про доцільність використання електроіскрових покриттів для різних умов тертя.