Wear Process Research Articles

Corrosion and wear resistance of SiC:Cu:a-C composite films prepared by magnetron sputtering

SiC:Cu:a-C composite films were prepared by the RF magnetron sputtering technique, and the effects of different SiC contents on the structure and properties of the films were investigated. Results show that when the SiC sputtering power is 250 W, the corrosion current density is as low as 3.81 × 10−8 A·cm−2, which is three orders of magnitude lower than that of the pure Cu substrate. The average friction coefficient of the film is as low as 0.08. Further analysis shows that the increase in hydrocarbon and graphite-like structure in the composite films leads to a lower surface energy and polarization intensity with the rise in SiC sputtering power. Moreover, the papillae-structured with gradually increasing surface roughness of the film makes it more stable in contact with water droplets, which results in the excellent hydrophobic properties of the film. Meanwhile, more nano-SiC particles are uniformly dispersed in the composite films, which inhibits the growth of Cu grains and reduces the porosity in the film. Ultimately, the corrosion resistance of the film is improved. The nanocomposite structure formed in the film tightens the bond and reduces the shedding of SiC particles and three-body abrasive wear during the frictional wear process. The increased degree of graphitization in the film is beneficial to reduce the coefficient of friction.

Experimental Investigation of Tip Wear of AFM Monocrystalline Silicon Probes.

AFM has a wide range of applications in nanostructure scanning imaging and fabrication. The wear of AFM probes has a significant impact on the accuracy of nanostructure measurement and fabrication, which is particularly significant in the process of nanomachining. Therefore, this paper focuses on the study of the wear state of monocrystalline silicon probes during nanomachination, in order to achieve rapid detection and accurate control of the probe wear state. In this paper, the wear tip radius, the wear volume, and the probe wear rate are used as the evaluation indexes of the probe wear state. The tip radius of the worn probe is detected by the nanoindentation Hertz model characterization method. The influence of single machining parameters, such as scratching distance, normal load, scratching speed, and initial tip radius, on probe wear is explored using the single factor experiment method, and the probe wear process is clearly divided according to the probe wear degree and the machining quality of the groove. Through response surface analysis, the comprehensive effect of various machining parameters on probe wear is determined, and the theoretical models of the probe wear state are established.

Driver Drowsiness Detection: A Machine Learning Approach on Skin Conductance.

The majority of car accidents worldwide are caused by drowsy drivers. Therefore, it is important to be able to detect when a driver is starting to feel drowsy in order to warn them before a serious accident occurs. Sometimes, drivers are not aware of their own drowsiness, but changes in their body signals can indicate that they are getting tired. Previous studies have used large and intrusive sensor systems that can be worn by the driver or placed in the vehicle to collect information about the driver's physical status from a variety of signals that are either physiological or vehicle-related. This study focuses on the use of a single wrist device that is comfortable for the driver to wear and appropriate signal processing to detect drowsiness by analyzing only the physiological skin conductance (SC) signal. To determine whether the driver is drowsy, the study tests three ensemble algorithms and finds that the Boosting algorithm is the most effective in detecting drowsiness with an accuracy of 89.4%. The results of this study show that it is possible to identify when a driver is drowsy using only signals from the skin on the wrist, and this encourages further research to develop a real-time warning system for early detection of drowsiness.

Aspects of the Nature of Wear

Purpose of reseach was a comprehensive study of the nature of wear of rubbing surfaces.Methods. The wear of parts is accompanied by complex physico-chemical phenomena. The wear rate depends on the material and quality of the rubbing surfaces, the nature of the contact and the speed of their mutual movement, the type and value of the load, the type of friction and lubrication, the quality of the lubricant, the presence of a third body between the contacting surfaces and many other factors. If we proceed from the definition of wear according to GOST, the key cause of wear is the destruction of the crystal lattice of a solid, due to the loss of its strength, into fragments (blocks or particles) of a certain dimension with their subsequent removal from the contact zone of tribosurfaces. However, the detailed mechanism of material separation from the friction surface is far from clear and has not been worked out from the standpoint of classical materials science. An approach to the representation of the nature of friction and wear is proposed. The crystal lattice of any metal, and even more so of an alloy, is an anisotropic medium and this anisotropy is significantly enhanced on the scale of the crystal structure of the alloy, since the orientation of the crystal structure inside each grain is multidirectional. Consequently, the stress-strain state of the structure in the surface layer of tribo-tension must be evaluated from the standpoint of the anisotropy of the medium.Results. To assess the impact on the wear processes, the following factors were investigated: load-speed; physical and mechanical; structural; thermophysical. An original technique for determining the intensity of wear has been developed, which makes it possible to evaluate and predict the durability of a particular friction unit. Comparison with the experiment showed satisfactory convergence in this range of changes in factors affecting the wear process.Conclusion. The nature of wear consists in the presence of stresses in the materials of the contacting surfaces, which tend to get rid of them by dispersing individual particles of different dimensions, approaching the minimum of entropy production.

Mixed thermo-elasto-hydrodynamic lubrication and wear coupling simulation analysis for dynamical load journal bearings

In the crankshaft-connecting rod system of the diesel engine, the complicated lubrication and wear mechanisms of journal bearings are comprehensively affected by the elastic deformation effect, the asperity contact effect, the thermal effect as well as the lubricating oil viscosity-temperature effect. This paper proposes an adaptive iterative method based on a mixed thermo-elasto-hydrodynamic (TEHD) lubrication and wear coupling model to investigate the lubrication and wear behaviors of journal bearings in the mixed lubrication. The evolution laws of the oil film thickness, the hydrodynamic pressure, the asperity contact pressure, the friction power loss, and the wear distribution are discussed and compared under different running times, oil temperatures, external loads, and shaft rotational speeds. The three-dimensional surface models based on the asperity contact power loss and the maximum wear depth with the variation of the running time and the oil temperature are fitted under specific external loads and shaft rotational speeds. The simulation results demonstrate that the bearing wear process includes the initial wear stage and the stable wear stage, which has a significant influence on the changing trend and distribution of lubricating parameters. The three-dimensional surface fitting models can provide theoretical guidance for the future performance prediction of journal bearings under time-varying working conditions.

The Particle Breakage Effect on Abrasive Wear Process of Rubber/Steel Seal Pairs under High/Low Pressure.

Pressure has a significant effect on rubber seal performance in the abrasive environments of drilling. The micro-clastic rocks intruding into the seal interface are prone to fracture, which will change the wear process and mechanism, but this process is not yet known at present. To explore this issue, abrasive wear tests were carried out to compare the failure characteristics of the particles and the variation wear process under high/low pressures. The results show that non-round particles are prone to fracture under different pressures, resulting in different damage patterns and wear loss on the rubber surface. A single particle force model was established at the soft rubber-hard metal interface. Three typical breakage types of particles were analyzed, including ground, partially fractured, and crushed. At high load, more particles were crushed, while at low load, shear failure was more likely to occur at the edges of particles. These different particle fracture characteristics not only change the particle size, but also the state of motion and thus the subsequent friction and wear processes. Therefore, the tribological behavior and wear mechanism of abrasive wear are different at high pressure and low pressure. Higher pressure reduces the invasion of the abrasive particles, but also intensifies the tearing and wear of the rubber. However, no significant differences in damage were found for steel counterpart throughout the wear process under high/low load tests. These results are critical to understanding the abrasive wear of rubber seals in drilling engineering.

Wear and Leakage Behaviors of Brush Seal Considering Eccentricity and Radial Deformation

Brush seals can improve engine performance by reducing leakage. Wear models of brush seals provide methods to predict wear and leakage. However, rotor eccentricity, radial deformation, and hysteresis effect of bristles are not considered systematically in the existing models, which may lead to large errors in some cases. To investigate the influence of rotor-stator eccentricity and radial deformation on the wear process and leakage performance of brush seal, a brush seal test was planned and executed, in which the air leakage rates were measured at different testing times and operating conditions, the eccentricity and radial deformation was measured using eddy current sensors. The test results showed that the eccentricity and radial deformation significantly affected the wear behavior and leakage performance. In the theoretical research, the abrasive wear equation is adopted to describe the material loss of bristles, and a simplified description is used to express the rotor-stator eccentric motions. To describe the effect of hysteresis on wear behavior, the deformation of the bristle pack is divided into rebounding deformation and locked deformation, and the two deformation modes are modeled separately. Then a brush seal wear model considering rotor-stator eccentricity and radial deformation is obtained, in which the hysteresis effect is especially represented. The wear model was verified quantitatively based on the brush seal test data, and the results show that there is an error of 20% with the calculated wear loss when rotor eccentricity, radial deformation, and hysteresis effect are comprehensively considered. In contrast, ignoring the hysteresis effect may increase the error by several times. This study provides a quantitative and practical method for predicting the wear and leakage of brush seals.

Hydrogen-Containing “Green” Fuels Influence on the Thermal Protection and Formation of Wear Processes Components in Compression-Ignition Engines Modern Injection System

The article describes the impact of hydrogen-containing vegetable fuels consumption with modern injection apparatus. The fuel in question is B100 rapeseed oil ethyl ester. The process of atomizing fuel in the engine at high temperature and in a high pressure chamber plays an important role in the combustion processes in the CI engine. The elements responsible for supplying fuel to the engine’s combustion chamber are the injectors and the injection pump. The paper presents the construction and operation of modern injection pumps and fuel injectors, the methods of their diagnosis are discussed, the important role of precision, and the course of their wear phenomenon are indicated. The paper discusses the impact of hydrogen-containing “green” vegetable fuels on the durability and reliability of injection pumps and fuel injectors used in Common Rail systems. In addition, the tests on the operating parameters of the fuel injector and pump operating on conventional fuel and hydrogen-containing “green” biofuel were carried out.

Effects of brake wear nanoparticles on the protection and repair functions of the airway epithelium

Long term exposure to particulate air pollution is known to increase respiratory morbidity and mortality. In urban areas with dense traffic most of these particles are generated by vehicles, via engine exhaust or wear processes. Non-exhaust particles come from wear processes such as those concerning brakes and their toxicity is little studied. To improve our understanding of the lung toxicity mechanisms of the nanometric fraction of brake wear nanoparticles (BWNPs), we studied whether these particles affect the barrier properties of the respiratory epithelium considering particle translocation, mucus production and repair efficiency. The Calu-3 cell line grown in two-compartment chambers was used to mimic the bronchial epithelial barrier. BWNPs detected by single-particle ICP-MS were shown to cross the epithelial tissue in small amounts without affecting the barrier integrity properties, because the permeability to Lucifer yellow was not increased and there was no cytotoxicity as assessed by the release of lactate-dehydrogenase. The interaction of BWNPs with the barrier did not induce a pro-inflammatory response, but increased the expression and production of MU5AC, a mucin, by a mechanism involving the epidermal growth factor receptor pathway. During a wound healing assay, BWNP-loaded cells exhibited the same ability to migrate, but those at the edge of the wound showed higher 5-ethynyl-2′-deoxyuridine incorporation, suggesting a higher proliferation rate. Altogether these results showed that BW.NPs do not exert overt cytotoxicity and inflammation but can translocate through the epithelial barrier in small amounts and increase mucus production, a key feature of acute inflammatory and chronic obstructive pulmonary diseases. Their loading in epithelial cells may impair the repair process through increased proliferation.

Tension Twinning Activity in As-Extruded ATZ632 Alloy During Friction and Wear Processes

Tension Twinning Activity in As-Extruded ATZ632 Alloy During Friction and Wear Processes

Study on Wear Properties of the Graphite-Sealing Surfaces in a Triple Eccentric Butterfly Valve Based on EDEM-Fluent Coupling

When using valves and pipes, erosion wear is a major issue. Erosion wear can result in equipment shutdown, material replacement, and other issues, as well as the failure of sealing surfaces. The depth of erosion wear is primarily determined by particle velocity, particle size, target material, and use conditions. A combination of the discrete element method (DEM) and computational fluid dynamics (CFD) was used in this study. The dynamic process of particle collision with the sealing surface is also considered. The wear depth was then calculated using Archard’s abrasive wear theory. The erosion wear process of the graphite-sealing surface by gas-solid two-phase flow medium is numerically simulated in a high-temperature triple eccentric butterfly valve using the above theory and method. The erosion wear patterns of graphite-sealing surfaces were investigated under various particle velocities, particle sizes, target materials, and service conditions. The findings indicate that particle velocity and particle size are positively related to wear rate. Soft target wear depth is greater than hard target wear depth. The wear depth decreases as the ambient temperature rises. As a result, graphite has excellent resistance to erosion and wear at high temperatures. When feeding, however, particle velocity and particle size must be considered. The erosion wears characteristics of a high temperature three eccentric butterfly valve investigated in this paper can be used to optimize erosion wear prevention.

Tribological performance of TiB2-graphene Al 7075 hybrid composite processed through squeeze casting: At room and high temperature

The increasing demand for wear-resistant materials can be addressed by using advanced hybrid aluminum composite materials. This research focuses on developing an improved tribological performance material made of Al7075 alloy reinforced with TiB2 and graphene. The tribological performance were assessed against different environments to find their best characteristics. The effect of incremental graphene addition (0.1%, 0.2%, and 0.3% weight) and the processing route (squeeze casting) of the hybrid composite on the wear characteristics have been evaluated. Microstructure and phase characterization of the novel composite material are analyzed by means of Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear resistance of the proposed material is assessed at room and high temperatures for different values of the applied load. It is found that the wear rate decreases as graphene content becomes higher. The wear mechanism at room temperature is driven by adhesion, while abrasion governs the wear process at high temperatures. Furthermore, wear turns from moderate to severe as temperature increases. Microscopic inspections of worn-out surfaces and debris confirm the change in wear behavior observed moving from room to high temperature.

Effect of Continuous Laser Treatment on the Wear Resistance of Hard Alloy WCo8

The hardening of hard alloy WCo8 was performed by continuous laser radiation with a laser beam of 1 mm/min diameter, laser radiation power of 200 W, and different speeds of laser beam movement. After laser treatment of hard alloy WCo8, diamond-abrasive wear tests were performed. Duration of the tests varied: 3–6–9 minutes; then the wear, intensity of wear, wear rate were calculated. The analytical dependences of determining the diamond-abrasive wear of hard alloy WCo8 depending on three parameters (power, laser beam propagation speed and duration of the diamond-abrasive wear process) were evaluated. There are no methodological difficulties in applying those dependencies, therefore we get high reliability of the results obtained in that case and the possibility to further calculate the effect of increasing the power and speed of laser radiation on the diamond-abrasive wear.

Effect of angular mismatch on tribocorrosion at taper-trunnion junction using a finite element model considering mechanical and chemical wear

Wear debris and metal ions arising from tribocorrosion at the taper-trunnion junction have been associated with early complications after total hip replacement. Wear and electrochemical phenomena occur simultaneously in this tribo-system, however, chemical wear has been usually neglected in previous computational studies on the interface damage. In this study, we developed a finite element model incorporating both the mechanical and chemical wear processes, and then investigated the effect of taper mismatch on the tribocorrosion at a CoCr/Ti6Al4V taper interface. This model was initially verified through a ball-on-disk wear testing and then applied to the study of degradation mechanism at the taper-trunnion junction. It was found that material loss at the taper-trunnion junction was linearly related to the number of gait cycles and chemical wear was evident, contributing up to 26 % to total material loss. A taper mismatch as small as possible was not necessarily beneficial to minimize the material loss. Instead, a larger positive taper mismatch helped reduce total wear volume but maximized the contribution of chemical wear. The model with a negative taper mismatch performed better than the ones with a positive taper mismatch in terms of corrosion resistance. These findings would benefit preoperative planning and the design of implant with reduced risk of tribocorrosion and failure.

Study on microstructure, mechanical and wear behavior of AA7075/hBN composites fabricated via liquid metallurgy

These research works investigate microstructure, mechanical strength and wear characteristics of AA7075/ hBN composites. AA7075/hBN composites are manufactured through two- step stir casting techniques with varying (0–7.5 wt%) hBN particles and subjected to T6 heat treatment. The optical microscopy of the composites shows that the reinforcement particles were distributed finely and with few cluster formations. The results stated that improved hardness on AA7075/5.0 wt% hBN composite as compared to as-cast alloy. The wear behaviour of alloy and composites are analysed on a pin-on-disc tribometer with varying applied loads of (20–60 N), a sliding velocity of 2.0 m/s, and a sliding distance of 3000 m, with EN31 steel as a counterpart. The wear rate and coefficient of friction of the composite reduced as the hBN particle concentration increased. A scanning electron microscope (SEM) is used to analyses the wear process on the worn surface, its reveals abrasion, oxide layer, and delamination as wear mechanisms under varying applied load conditions.

Experimental study on the influence of slip ratio on irregular wear behaviors of wheel/rail

This study aimed at investigating the effect of slip ratio on the wheel-rail polygonal wear using a twin-disc machine. The slip ratio used in the test included 0.91%, 3.83%, 4.55% and 9.43%. The profile of samples, vibration, wear and damages were analyzed. Through establishing the relationship between speed, frequency and slip ratio, the conditions for generating apparent polygons were analyzed. The results indicate that under the lower slip ratio, the wheel-rail system has no obvious main vibration during the wear process and is not easy to generate polygon wear. With the increase in the slip ratio, the wheel-rail system easily excites some polygonal characteristic frequency during the wear process. When the characteristic frequency is excited and the frequency amplitude increases continuously, the sample produces obvious polygon wear of corresponding order. When the characteristic frequency is excited but the amplitude of frequency is low, the sample will easily produce slight polygon wear. In addition, when obvious polygonal wear is generated, the damage form at the crest is rolling contact fatigue wear and a small amount of peeling pits, and the damage form at the trough is the severe peeling. Meanwhile, the hardness and plastic deformation layer thickness in the crest region is lower than in the trough region.

Improved High‐Temperature Softening Resistance and Wear Resistance of AISI M42 High‐Speed Steel by N‐Alloying

Herein, a novel high‐nitrogen (0.18 wt%) M42 high‐speed steel is fabricated by pressurized metallurgy. The high‐temperature softening resistance of N‐free and 0.18N steels is evaluated by hardness measurement at room temperature after additional heating at 600 °C for various times, and the high‐temperature wear resistance is evaluated by ball‐on‐disk dry sliding wear test at 600 °C. The microstructure is characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and high‐resolution transmission electron microscope (HRTEM). The results indicate that the hardness of 0.18N steel is 2–3 HRC higher than that of N‐free steel after additional heating at 600 °C for 4–120 h. The superior high‐temperature softening resistance of 0.18N steel is primarily ascribed to the smaller coarsening rate of M2C secondary carbides. Under the dry sliding condition at 600 °C, the wear rate of N‐free steel is approximately 1.5 times higher than that of 0.18N steel. The better high‐temperature wear resistance of 0.18N steel is primarily because the superior softening resistance makes it maintain higher hardness during the wear process to provide stronger support for the oxide layer and increase the protective ability of oxide layer to steel.

Effect of quenched-tempered heat treatment on the wear resistance mechanism of zirconia toughened alumina ceramic reinforced high chromium cast iron architecture composite

Zirconia toughened alumina (ZTA) ceramic particles can significantly enhance the wear resistance of high chromium cast iron (HCCI). In this study, the effect on the wear resistance of quenched and quenched-tempered heat treatment for ZTA/HCCI architecture composites has been investigated. After three-body abrasive wear, the quality loss ratio of quenched and quenched-tempered composites was 0.31 % and 0.29 %, respectively; while the quality loss ratio of quenched-tempered HCCI was 0.58 %, which means the wear resistance of ZTA/HCCI composites enhanced. The matrix microstructure of HCCI transferred to martensite or tempered martensite, which made the metal uniformly distribute and ensure the relatively high hardness of ZTA/HCCI architecture composites. Then, the worn surface structure of the ZTA/HCCI architecture composites revealed that ZTA ceramic particles have a shadow effect to enhance the wear resistance of HCCI. The wear process of the composite can be summarized into four stages: First, martensite or tempered martensite peels off and accompanies by a work-hardening process at the surface. Second, carbide starts to crack and break. Third, the size of the composite diffusion layer boundary starts to decrease. Finally, ZTA ceramic particle surface breaks and the composite enters a state of instability. The ZTA/HCCI composites heat treatment process can give an idea for machinability and excellent wear resistance.

Influences of abrasive particles on tribological behaviours of rotary vane steering gear seals under oil

The wear particles often cause the abnormal wear processes to the rotary vane seals, which lead to seals failure and dropping hydraulic oil pressure, and eventually result in losing of the function of rotary vane steering gear. Clarifying the friction and wear mechanisms between the vane seals and the cylinders and extracting their key wear characteristics are the keys to extend the service life and realize intelligent fault diagnosis of the rotary vane steering gears. Different kinds of hydraulic oils mixed up with different sizes of iron particles were chosen to investigate the abrasive particles on the wear behaviours between the polyurethane polymer and carbon steel specimens. The wear characteristics such as coefficients of friction (COF), wear morphologies, frictional-induced vibration signals were examined and analyzed synthetically. The results showed that the coefficients of friction, wear morphologies, surface roughnesses and vibration signals increased as a function of the iron particle sizes, which indicated that the wear state was gradually worsening. The three-body friction and wear mechanisms were disclosed clearly. There was a certain mapping relationship between the wear characteristics and wear states, and sensing the tribological information between the rubbing pairs, including coefficient of friction, abrasive particle size in hydraulic oil, wear morphology, vibration signal and other characteristics, was a potential and effective way for evaluating or predicting the wear states or failure modes of rotary vane steering gear seals. This study provides a theoretical basis for revealing the friction and wear mechanisms of ship rotary vane steering gear seals, and is useful for accomplishing their intelligent monitoring and fault diagnosis.

Calibration procedure for ultrasonic sensors for precise thickness measurement

The conveyor belt, the most expensive element of the conveyor, during many years of operation is subject to complex wear processes related to the processes of its friction against the debris and structural elements, fatigue processes related to its bending on drums and idler sets, and repeated changes in tension when starting the conveyor and passing through the driving drums. The rate of wear processes is proportional to the time and intensity of the belt operation (the number of cycles of the belt loop around the conveyor). Another character, sudden and random, is the belt damage that occurs during the fall of the spoil onto the belt. Smaller lumps accelerate the friction processes by damaging the surface of the covers (rubber cracks, small tears) and intense friction caused by the acceleration of the excavated material. Larger lumps with energy exceeding the limit values cause the belt to puncture through, tearing out parts of the cover or rim, and damage to the core. As the belt wears off, the energy limits decrease (due to the decreasing belt thickness), which significantly accelerates the rate of its degradation processes. Identifying the rate of change in belt thickness over the entire surface is therefore critical to estimating the remaining life of the belt. The implementation of non-invasive diagnostics of conveyor belts to assess the condition of its core and the degree of abrasion allows for a significant reduction in belt operating costs. It can contribute to the extension of its life by reducing uneven wear and damage to the core. The decision to replace the belt at the right moment allows it to be regenerated. Regular control of the condition of damage and abrasions of the belt can prevent the occurrence of major failures and plan the moments of preventive replacements, which are much cheaper than expensive emergency replacements that can additionally cause enormous production losses. Prediction of the replacement of belt sections and their length allows for proper management of the budget allocated to repair and replacement of belts. Thanks to the obtained detailed information on the degree of belt wear, it is possible to take ad hoc corrective actions to extend the life of the belts and to predict the remaining time of its failure-free operation in the adopted replacement strategy. In Poland, at the Wrocław University of Science and Technology, as a result of many years of research work financed by the National Center for Research and Development, diagnostic systems have been developed to assess the technical condition of conveyor belts. One of such devices is the ultrasonic system for continuous belt thickness measurement, which is being built under the LIDER X project, called BeltSonic. This article presents the method of calibrating this device and the obtained measurement accuracy. Accurately measuring the thickness of the strip over its entire surface is critical to forecasting its remaining life.