Frictional Wear Characteristics Research Articles

Comparative Study on the Wear Characteristic and Control Method of Rail Corrugation in Typical Fastener Sections

This paper conducts a comparative study on the severity, development trends of rail corrugation, and the suppression effects of rail vibration absorbers on small-radius curved track sections supported by two types of typical fasteners. Firstly, a finite element model (FEM) of the wheel-rail system for small-radius curved track sections is established based on field investigation data. Then, a comparative analysis is conducted on the frictional coupling vibration characteristics and wear characteristics of the rail surface for wheel-rail systems in the two typical fastener sections. Additionally, the suppression effect of installing rail vibration absorbers on rail corrugation is analyzed. The results indicate that the frictional coupling vibration in the wheel-rail system is the primary cause of rail corrugation on small-radius curved track sections, and the vibration response of the wheel-rail system in the Cologne egg fastener section is significantly greater than that in the DTVI2 fastener section. Furthermore, rail corrugation in the Cologne egg fastener section is more severe and develops faster compared to the DTVI2 fastener section. Finally, the installation of vibration absorbers suppresses rail corrugation in both fastener sections, with a more pronounced suppression effect observed in the Cologne egg fastener section.

Increasing Wear Resistance of Ploughshare by Electrofriction Treatment

Surface layers of agricultural machinery working bodies are subjected to intensive abrasive wear during operation, which leads to rapid wear of equipment and reduction of its service life. To increase the wear resistance of the working surfaces of tools, the method of induction cladding using ‘Sormait-1’ materials is widely used. However, after coating, additional heat treatment is required, which improves physical and mechanical properties of the material and increases its durability. When using electrofriction technology (EFT) hardening, the surface of the parts is subjected to melting under the influence of electric arcs, which affects the surface characteristics of the coatings. In this work, two types of surface treatment of L53 steel were investigated: induction cladding using ‘Sormait-1’ material, as well as a combination of induction cladding and subsequent electrofriction treatment. The coatings were characterized and compared with the substrate in terms of the following parameters: microstructure, phase composition, hardness distribution, and friction-wear characteristics. After induction cladding of the Sormait-1 material, a dendritic structure was formed; however, subsequent electrofriction treatment resulted in a reduction of this dendritic structure, which contributed to an increase in the hardness of the material. The average hardness of the coatings after electrofriction treatment was 786 HV0.1, which is more than three times the hardness of the substrate. Furthermore, the influence of structural characteristics and hardness on abrasive wear resistance was examined in accordance with ASTM G65 international standards. Field tests were conducted on plough shares before and after electrofriction hardening to evaluate their performance. Each ploughshare was scanned with a structured 3D scanner before and after use in the field. From the scan data, the cutting-edge profile was calculated and three key parameters were determined: linear wear, volumetric wear, and mass reduction. According to the results of field tests, it was found that the service life of the blades hardened by electrofriction technology was 12%–14% higher compared to serial blades processed by induction cladding with the use of ‘Sormait-1’ material. Operational tests of hardened plough shares confirmed the results of laboratory tests and proved the advantages of electrofriction technology for increasing the wear resistance of soil tillage machine working bodies.

Influence of Binding Agent on the Cutting Performance and Friction Wear Characteristics of Catalytic Composite Abrasive Cluster

To improve the polishing efficiency and process stability of catalytic composite abrasive clusters (CCAC), CCAC containing different binding agent ratios was investigated. Five groups of CCAC with different binding agent ratios were prepared for friction chemical polishing of silicon carbide (SiC), respectively. Based on material removal rate (MRR) and surface roughness (Ra) as evaluation metrics, the polishing performance of five groups of CCAC were compared. Subsequently, wear experiments were carried by block shaped CCAC with diameter of 1.6 mm, as well as single crystal diamond (SCD) abrasives with the same particle size. The friction coefficient and the cross-sectional area at the worn area of wear were measured to evaluate the effect of binding agent content on the continuous cutting performance of the abrasive as well as on the tribological properties. The experimental results showed that #3 abrasive exhibited the highest machining efficiency (MRR reaches 330.535 nm min−1) and better surface roughness (Ra reaches 22.741 nm). Excessive or insufficient bonding agent in CCAC will affect the processing performance of the abrasive. When the proportion of binding agent in the abrasive is 25%, CCAC has better processing ability and can realize efficient polishing of SiC wafers.

Experimental study on tribological behavior of a binderless cemented carbide at high contact stress

Knowledge of frictional evolution and associated damage mechanism during sliding wear conditions using binderless WC-based cemented carbide is lacking. In this study, the frictional evolution and corresponding transformation of microstructure, and wear mechanisms of Al2O3/WC-based cemented carbide due to the effect of different contact pressure, especially high pressure have been explored using a reciprocating ball-on-flat sliding wear tester, which was experimentally simulated following the ASTM G133–02 standard. The dynamic curves in friction coefficient with the sliding time were described. The microscopic 3D topography of contact surface was obtained by the MFP-3D atomic force microscope. The material removal and the wear rate were discussed. Worn surface morphologies at different moments, cross-sectional images of wear tracks at different loads, and wear debris were taken by field emission scanning electron microscope. The results suggested that the pressure plays a decisive role in frictional evolution and wear characteristics. Two models of frictional evolution were declared. A novel “surge” phenomena in friction coefficient was found and explained at high contact pressure. Wear transition from mild wear to severe wear was confirmed. More than one wear mechanism was observed, including micro-cutting (polishing), generation and propagation of cracks, cracking-induced spalling, plastic deformation, and the formation of tribolayer.

Sticky feet: a tribological study of climbing shoe rubber

This study examines the tribological properties of climbing shoe rubbers, challenging the common belief in the climbing community that softer rubbers are inherently grippier. This study investigates the mechanical and wear characteristics of climbing shoe rubbers by employing a high-precision modular mechanical testing environment (Bruker UMT TriboLab) and representative granite counter-surfaces. Key parameters, including surface roughness, Shore A hardness, interfacial adhesion, static and dynamic friction coefficients, and material wear patterns, were analyzed. The mechanical properties of each rubber compound were characterized through Shore A hardness testing and ball indentation–retraction tests, measuring indentation force, energy, and adhesive properties. Sliding friction tests, simulating real climbing conditions, were conducted to understand the tribological behavior of each rubber compound under different loads, further analyzing static and dynamic friction coefficients and wear characteristics. The findings of this study indicate that rubber performance is a convolution of several factors, including material hardness, surface roughness, and interfacial adhesion. Contrary to popular belief, softer rubbers did not consistently exhibit superior tribological characteristics. The findings of this study suggest that climbing shoe selection and design should consider a broader range of material characteristics beyond hardness, emphasizing the role of surface roughness and adhesion in determining overall frictional performance. This research offers valuable insights for the climbing community, providing methodologies to benchmark climbing rubber material characteristics.

Impact of laser energy density on the structure and properties of laser-deposited Fe‒Ni‒Ti composite coatings

To utilise laser deposition for the preparation of high-strength, wear-resistant components, the service life of components in rail transportation equipment should be improved. Laser deposition technology is used to fabricate Fe‒Ni‒Ti coatings on the surface of AISI 1045 steel substrates. By varying the laser power to adjust the laser energy density, Fe‒Ni‒Ti composite coatings are prepared at various energy densities. The morphology, microstructure, phase composition, tensile strength, microhardness, and friction-wear characteristics of the composite coatings are observed and tested. The influence patterns and mechanisms of laser energy density on the organisational variation and friction-wear performance of composite coatings is investigated. When the laser energy density is 97.2 J/mm2 (1400 W), the residual stresses in the deposition layer are minimised, resulting in fewer cracks and gas pore defects, with a porosity rate reaching its lowest value of 1.2% and a density of 99.1%. With the increase in energy density, both the tensile strength and elongation of the deposited layer exhibited an initial increase followed by a decrease. The hardness and wear resistance of Fe‒Ni‒Ti deposition layers is effectively controlled by regulating the laser energy density.

Effect of PVD deposition method on indentation and friction wear characteristics with hydrogen embrittlement of CrN coated stainless steel for electric vehicle hydrogen valves

In this investigation, a chromium nitride layer was deposited on general austenite stainless steel (UNS S31603) by means of the physical vapor deposition coating method to improve the hardness, wear resistance, and hydrogen embrittlement resistance. Accordingly, the purpose of this investigation is to study the effect of different physical deposition methods on mechanical characteristics due to hydrogen embrittlement. Both the indentation and friction characteristics of the chromium nitride layer with in response to hydrogen embrittlement were examined. The ion beam-assisted deposition (IBAD) and arc ion plating (AIP) methods were used to densely deposit the coating layer with a thickness of approximately 2.0∼2.5 μm, and the hardness increased by around 1180.9 HV and 1638.6 HV, respectively, when compared with the base material (292.6 HV). In terms of the coating layer deposited using the IBAD method, all the base material was exposed after hydrogen embrittlement for 3 h, whereas in the case of the coating deposited using the AIP method, the base material began to be exposed locally following hydrogen embrittlement for 12 h. For the IBAD- and AIP-deposited coatings, the average friction coefficient was calculated as 0.52 and 0.34, respectively. In the case of the coating layer deposited using the IBAD method, the average friction coefficient increased by 0.29 after hydrogen embrittlement for 3 h, whereas the average friction coefficient of the coating layer deposited using the AIP method increased by 0.04 after hydrogen embrittlement for 48 h. Therefore, it can be seen that the AIP method is significantly better than IBAD in terms of mechanical characteristics with hydrogen embrittlement.

Synergistic effects of fabrication techniques and the interface structure on the tribological properties of reduced graphene oxide/CuCr composites

While the copper/graphite composite offers commendable anti-friction and wear resistance, it falls short in fulfilling the demands of specific applications such as special brushes, high-speed rail overhead conductors, and sliding contact materials. Due to its exceptional mechanical, electrical, frictional, and wear-resistant properties, reduced graphene oxide (RGO) is considered a promising reinforcement material for copper-based wear-resistant materials. In this study, we synthesized RGO/CuCr composites using flake powder metallurgy and spark plasma sintering (SPS) techniques. The formation and evolution of lubricative films on the RGO/CuCr composite's worn surface were scrutinized, alongside the effects of reinforcement concentration and frictional load on friction-wear characteristics. Notably, increasing the RGO content from 0 to 4.0 vol% led to a reduction in the average friction coefficient from 0.81 to a minimum of 0.314, concurrent with a 62.4% drop in the wear rate. The overall enhancement in properties can largely be credited to the optimized interfacial adhesion between RGO and the CuCr matrix facilitated by in-situ interfacial carbides and the inherent self-lubrication capability of RGO. A developed physical model showcased a direct relationship between the friction coefficient of RGO/CuCr composites and the experimental load, offering a quantitative interpretation of the load's influence on the composite's friction coefficient. Therefore, this research paves a theoretical and practical pathway to engineer high-performing RGO-reinforced copper matrix composites for wear-resistant applications.

Multi-response optimization of M2 steel coatings deposited by co-axial laser cladding on A2 steel tool surfaces

Laser cladding is a highly effective technique used in additive manufacturing to enhance the surface properties of workpieces. It is employed to improve wear resistance, corrosion resistance, and high-temperature resilience of materials. This study explores the utilization of laser cladding technology to repair the surface of AISI A2 tool steel by applying a coating of M2 steel. Sixteen experiments were designed using an orthogonal methodology to investigate the intricate relationship between various processing parameters, including laser power, scan speed, powder feed rate, and overlapping ratio. These parameters were examined in conjunction with key mechanical properties of the coating, such as micro-hardness, friction-wear characteristics, and shear bond strength.Additionally, analytical techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD) were employed to gain insights into the microstructure of the coatings and elucidate the underlying failure modes. Shear testing of the coatings indicated a tendency towards a brittle fracture mode within the coating, with the dominant wear mechanism involving a combination of abrasive and oxidative wear.Finally, a TOPSIS-Grey Relational Analysis (GRA) method was utilized to identify the optimal process parameters. These optimal parameters were determined to be a laser power of 1200 W, a scan speed of 5 mm/s, a powder feed rate of 14 g/min, and an overlapping ratio of 30 %. Subsequent validation experiments carried out with these parameters demonstrated superior performance compared to the optimal group identified in the orthogonal experiment.

The size effect of molybdenum disulphide additives on friction and wear performance of lithium-thickened palm olein grease

Concern over commercial mineral-based grease’s impact on the environment and its unrenewable resources requires a more sustainable alternative in lubrication. In this research, a palm olein-based grease was developed, and the effect of particle size of molybdenum disulphide (MoS2) additives on the grease performance was experimentally evaluated. Molybdenum disulphide additive of 0.5 wt.% concentration that varied in size was added to the palm olein grease. The friction reduction and wear characteristics of the developed lubricants were evaluated using a four-ball tribometer. The wear surfaces were analyzed by scanning electron microscope, energy dispersive spectroscopy and infinite focus microscope. It was discovered that MoS2 improved the grease performance, and a nano size of 90 nm exhibited the best performance in reducing friction coefficient, wear parameters and surface roughness. This study suggests the potential of palm olein-based grease with MoS2 additive to be used as a lubricant.

Advancements in Polymer Friction and Wear: A Scratch-Modeling Approach

Due to its many applications, including assessing strength, fracture toughness, and so on, the scratch method has attracted much attention in the research community. Finding the tribological characteristics of polymers, such as friction and wear, proved difficult for scratch approaches. This study tested a constant loading scratch method with a Rockwell indenter on the polymeric surface to develop an accessible wear and friction calculation model. Scratch load, speed, and passes, three primary factors, are considered to observe the polymers' response, particularly in terms of width, penetration depth, residual depth, and percentage of recovery. Considering all these scratch parameters, the experiments were conducted on five polymers: polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), polypropylene (PP), high-density polyethylene (HDPE), and polymethylmethacrylate (PMMA). The scratch characteristics are considered to calculate the friction coefficient and wear throughout the scratching process. Increased groove width, penetration depth, and residual depth and a decrease in recovery percentage are the effects of the number of scratch passes. The strain hardening caused by the multiple movements of the indenter on the same grooves causes a behavior change. With an increase in the scratch pass, the coefficient of friction decreases and stabilizes, and the volumetric wear increases, suggesting that more scratch passes will cause more material loss. This study derived two distinct models by applying the least-square curve fitting technique to evaluate friction and material wear characteristics. This model demonstrates a high degree of compatibility with the specific characteristics of polymeric materials and exhibits a significantly low margin of error.

Tribological Behaviour of Furcraea Foetida Fiber-Reinforced Epoxy Composites under Varying Applied Loads

This study investigates the tribological behaviour of Furcraea Foetida fibre-reinforced epoxy composites under varying applied loads. The aim is to understand the influence of applied load on the frictional behaviour and wear characteristics of the composites. The study employs a pin-on-disk test to examine the frictional force, coefficient of friction (COF), and specific wear rate (SWR) of identical samples subjected to four different loads (80 N, 100 N, 120 N, 140 N). Scanning electron microscopy (SEM) is used to analyse the surface morphology under different loads. The frictional force versus sliding distance graph demonstrates an increasing trend from 80 N to 120 N, followed by minimal change at 140 N. Similarly, the COF versus applied load graph shows a progressive increase from 80 N to 120 N, with the least increase observed at 140 N. The SWR versus applied load graph indicates an increasing trend from 80 N to 120 N, with marginal variation at 140 N. SEM analysis reveals that only the sample subjected to 140 N shows evidence of plastic deformation. In conclusion, the results indicate that the applied load significantly influences the frictional behaviour and wear characteristics of the Furcraea Foetida fibre-reinforced epoxy composites. At higher loads, the increase in frictional force, COF, and SWR becomes less pronounced, suggesting potential saturation in the composites' response. The presence of plastic deformation at 140 N further highlights the unique behaviour observed at this load. These findings contribute to a better understanding of the tribological performance of the composites and have implications for their practical applications.

Influence of surface structure on friction and wear characteristics of silicone rubber for hydraulic rod seals.

This research investigates the impact of surface structure on the friction and wear characteristics of silicone rubber used as a material for hydraulic rod seals. Various silicone rubber specimens with different surface structures were prepared, and their surface morphology, water contact angle, and surface roughness were compared. Friction tests were conducted using a reciprocating sliding method to evaluate the friction coefficient and wear characteristics. The results revealed that the silicone rubber specimens coated with silicone powder exhibited a significant increase in surface roughness. However, this increase was accompanied by a decrease in surface energy, leading to the absorption and dispersion of contact pressure and frictional stress, resulting in a friction-reducing effect. Consequently, the silicone rubber specimens coated with silicone powder demonstrated a friction coefficient more than 70% lower on average compared to bare silicone rubber, and exhibited minimal wear characteristics. The irregular microstructures formed on the surface of the silicone rubber are believed to contribute to these friction and wear improvements. Alterations in stress and contact behavior of bare silicone rubber and silicone powder-coated silicone rubber with pre-curing time during indentation and sliding movements were validated through finite element analysis. These findings provide valuable insights for enhancing the performance and durability of hydraulic rod seals made from silicone rubber. This research is expected to contribute to further studies aimed at improving hydraulic seal materials.

Экспериментальное исследование трибологических характеристик перспективных самосмазывающихся материалов для быстроходных узлов трения

The paper considers a technique and a stand for experimental study of the tribological characteristics of materials for high-speed «dry» friction units that implement the «finger-disk» friction scheme. As a result of experimental studies, the tribological characteristics of traditional and promising domestic and foreign self-lubricating materials were determined. A significant dependence of the friction-wear characteristics of self-lubricating materials of high-speed «dry» friction units on the sliding speed has been established. At the same time, the best tribological characteristics in the entire range of sliding speeds from 10 m/s to 40 m/s correspond to the Kryolon-3 material.

Atomic Cross-Talk at the Interface: Enhanced Lubricity and Wear and Corrosion Resistance in Sub 2 nm Hybrid Overcoats via Strengthened Interface Chemistry.

Friction, wear, and corrosion remain the major causes of premature failure of diverse systems including hard-disk drives (HDDs). To enhance the areal density of HDDs beyond 1 Tb/in2, the necessary low friction and high wear and corrosion resistance characteristics with sub 2 nm overcoats remain unachievable. Here we demonstrate that atom cross-talk not only manipulates the interface chemistry but also strengthens the tribological and corrosion properties of sub 2 nm overcoats. High-affinity (HA) atomically thin (∼0.4 nm) interlayers (ATIs, XHA), namely Ti, Si, and SiNx, are sandwiched between the hard-disk media and 1.5 nm thick carbon (C) overlayer to develop interface-enhanced sub 2 nm hybrid overcoats that consistently outperform a thicker conventional commercial overcoat (≥2.7 nm), with the C/SiNx bilayer overcoat bettering all other <2 nm thick overcoats. These hybrid overcoats can enable the development of futuristic 2-4 Tb/in2 areal density HDDs and can transform various moving-mechanical-system based technologies.

Friction-Wear Characteristics of Carbon Fiber Reinforced Paper-Based Friction Materials under Different Working Conditions

To study the friction and wear performance of carbon fiber reinforced friction materials under different working conditions, paper-based friction materials with different fibers were prepared. Experiments on the SAE#2 test bench were conducted to study the infectors including friction torques, surface temperature, coefficient of friction (COF), and surface morphologies. The results were analyzed, which indicated that the carbon fiber reinforced friction material could provide a higher friction torque and a lower temperature rising rate under the applied high pressure and high rotating speed conditions. As the pressure increased from 1 MPa to 2.5 MPa, the friction torque of plant fiber reinforced material increased by 150%, the friction torque of carbon fiber reinforced material increased by 400%, and the maximum temperature of plant fiber reinforced and carbon fiber reinforced material reached the highest value at 1.5 MPa. Thus, carbon fibers not only improved the COF and friction torque performance but also had advantages in avoiding thermal failure. Meanwhile, carbon fiber reinforced friction materials can provide a more stable COF as its variable coefficient (α) only rose from 38.18 to 264.62, from 1 MPa to 2.5 MPa, which was much lower than the natural fiber reinforced friction materials. Simultaneously, due to the good dispersion and excellent mechanical properties of PAN chopped carbon fibers, fewer pores formed on the initial surface, which improved the high wear resistance, especially in the intermedia disc.

Frictional wear characteristics of nickel-based alloy and reactor material in pressure vessel reactor

Abstract The reactor pressure vessel was contact sealed with a double-channel O-ring made of Inconel 718 alloy and nuclear power material SA508. The fretting wear characteristics of Inconel 718 O-tube and SA508 plate friction pair were tested by fretting wear testing machine to explore the failure mechanism of reactor pressure vessel seal system. The test conditions are as follows: normal temperature, normal loads of 10, 20, and 40 N, displacement amplitude of 600 μm, the number of cycles of 10,000, and frequency of 4 Hz. Results show that the coefficient of friction (COF) increased with increasing normal force. Significant material losses were detected during the relative sliding of the contact surface of SA508. A large number of abrasive dust accumulated at the edge of the contact zone, forming a large number of oxides. During the friction of Inconel 718 O-ring, plastic deformation occurred, and a plastic flow layer was formed. The plastic deformation flow at the contact point formed an adhesive connection point, producing adhesive wear and oxidative wear. The wear mechanism was characterized by the combination of oxidative wear and abrasive wear.

Investigation of Dry Sliding Friction, Wear and Mechanical Behavior of the Ti-6Al-7Nb Alloy after Thermal Oxidation.

The mechanical and tribological characteristics of the Ti-6Al-7Nb alloy were investigated within a wide range of temperature and time parameters of thermal oxidation. The hardness, HIT, and indentation modulus, EIT, of the alloy in question, with and without an anti-wear oxide layer, were determined. The tribological properties of sliding couples were studied under technically dry friction conditions, using a ball-on-disc tribometer. The test pieces were non-oxidized and oxidized Ti-6Al-7Nb alloy discs, and Al2O3, ZrO2, and 100Cr6 balls were used as counter specimens. After thermal oxidation, the surface of the titanium alloy was characterized by a significantly higher hardness, HIT (8–10 GPa), compared to the surface not covered with oxide layers (3.6 GPa). The study showed that the curvature of the loading segments increased with an increasing oxidation temperature, indicating a strong positive dependence of hardness on the thermal oxidation temperature. The value of the indentation modulus, EIT, was also found to increase with the increasing oxidation temperature. The intensity of the tribological processes was strictly dependent on the oxidation parameters and the couple’s material (Al2O3, ZrO2, 100Cr6). It has been shown that the thermal oxidation process makes it possible to control, within a wide range, the friction-wear characteristics of the Ti-6Al-7Nb alloy.

Friction wear characteristics of a femtosecond laser-patterned amorphous carbon thin film

In this study, an amorphous carbon thin film on a cemented carbide substrate was prepared with surface micropatterns using femtosecond laser machining. The micropatterns that were considered were made of lines, dotted lines, and zigzag dotted lines. We performed a tribology test using a ball-on-disk friction wear test and investigated the coefficient of friction (COF) and wear amount as a function of pattern size and shape. The micropattern made using femtosecond laser patterning exhibited better friction coefficient properties than the bare amorphous carbon samples. Moreover, the pattern size and shape influenced the friction coefficient value of the patterned samples. The dotted line pattern shape showed superior results in friction coefficient characteristics compared to those of other micropatterns.

Effect of Silicon Carbide Nanoparticles on the Friction-Wear Properties of Copper-Based Friction Discs.

To study the influence of nano-additives on the friction-wear characteristics of friction materials, the nano-sized silicon carbide particles which have excellent chemical and physical properties are considered to add in composite to form the modified friction material. The influence of the silicon carbide nanoparticles (SCN) on the friction-wear characteristics of copper-based friction materials (CBFM) is investigated via the SAE#2 (made in Hangzhou, China) clutch bench test with the applied pressure, rotating speed, and automatic transmission fluid (ATF) temperature taken into account. Moreover, the variations of friction torque and temperature are considered to evaluate the friction performance, and the variable coefficient is employed to describe the friction stability. The wear characteristics of friction materials are investigated by the disc changes in thickness and micro-morphology. The results show that the CBFM with SCN can provide a higher friction torque, which increased by 30% to 50% compared with CBFM. The variable coefficient of CBFM with SCN changes from 674 to 52 with the rotating speed raised from 600 rpm to 3000 rpm, which shows that the friction stability is relatively worse. Furthermore, the micromorphology shows that the CBFM with SCN has lower porosity and surface roughness, which increases the microscopic contact area and the coefficient of friction (COF). Simultaneously, the reduction in porosity also leads to a decrease in the cooling quality, bringing about a rapid temperature rise. Thus, the wear amount of CBFM with SCN increases significantly, especially for the friction disc in the axial middle position.