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Composites made with a hybrid metal matrix have gained importance in recent times. In this study, the mechanical and tribological properties of Al7075/W/MoS2 hybrid composite materials were investigated using ultrasonic assisted stir casting method. The matrix material used was an aluminium alloy (Al7075), while the reinforcement comprised of tungsten (W) and molybdenum disulphide (MoS2) particles. MoS2 was added to the molten metal in a constant proportion of 1%, while tungsten particles were added in increments of 1%, 2%, and 3% to the matrix. The hybrid composite samples underwent mechanical characterisation to determine their tensile, impact, density, and hardness test, as well as tribological characterisation. The microstructure was also examined using a scanning electron microscope to understand the uniform distribution of reinforcement particles. The findings exhibited that addition of W and MoS2, characteristics improved steadily as compared to the base metal. The composites exhibited remarkable microstructure stability, high strength, and hardness. [ABSTRACT FROM AUTHOR]

Micro-electric Discharge-Milling (µ-ED-M) is a non-contact process that uses an electrical spark to remove the material from a submerged workpiece with an electrode in a dielectric. The present paper focuses on optimizing process energizing (Capacitor, Voltage) and process stabilizing (Tool Travel Speed, Nano-Powder) parameters for controlling the size and surface characteristics of micro-crater. The present work focuses on the effect of nano-powder concerning dimensional aspects and surface characteristics at high and low capacitance levels. A µ-slot has been generated on the copper material by a tungsten carbide electrode. The experimentation is performed with two capacitor levels and three voltage and tool travel speed levels using full factorial design technique using with and without mixing of nano-powder in dielectric. The desirability functional multi-objective optimization approach is used to analyze the MRR, TWR, Width, and Depth. Field emission scanning electron microscopy (FESEM), non-contact optical profilometer, and x-ray diffraction (XRD) techniques are used to analyze the surface morphology of machined surfaces. The ANOVA is used to optimize the results; at low discharge energy, tool travel speed contributes 41% and promotes a higher thickness of recast layer 12.7 µm, whereas high discharge energy and nano-powder concentration contribute approx.—36% with 8.56 µm of recast layer. [ABSTRACT FROM AUTHOR]

Higher chemical reactivity and lower thermal conductivity make titanium alloys "difficult to machine". The current experimental study emphases on the performance of various tools for turning biomedical titanium alloy under dry environment. The experimentation was carried out to study the effect of thicker CVD coating layers and uncoated tools by varying the process parameters (speed, feed). The reduction in forces and temperature was more significant as the speed was increased. Improved tool life with the use of CVD coated tool was achieved. Chip morphological study revealed formation of thinner chips with less serrations which proves occurrence of less plastic deformation with the use of CVD coated tool. From the experimental analysis, it was revealed that multilayer CVD coated tools showed enhanced results owing to extensive coating qualities. The CVD coated tool was found suitable for machining Titanium grade 23 under dry conditions at higher speed levels. [ABSTRACT FROM AUTHOR]

AbstractThe present research explores the mechanical and tribological behaviour of Ni-reinforced aluminium composite. The aluminium alloy-1050 series has generally poor wear resistance. To enhance the wear resistance, a bottom pour stir casting method has been used to reinforce the hard Ni particles in the aluminium alloy at different weight percentages (6, 12, 18 wt%). As per the microstructural analysis, the manufactured base and composite materials have a polycrystalline structure. The peritectic reaction creates a hard intermetallic Al3Ni phase in the composites in terms of chemical reactions between the aluminium and Ni. XRD analysis has demonstrated the presence of the Al3Ni phase in the composites. The Al3Ni phase’s strong atomic bonding has enhanced the work of adhesion, hardness, and wear resistance. The dry sliding wear behaviour of the cast-AA and composites has been examined by a pin-on-disc instrument at different loads (20 and 40 N) against a hardened EN31 steel disc. The worn surface SEM images resulted in the following wear mechanisms: ploughing, adhesion, delamination, and abrasion. The CoF and wear debris size have been increased by increasing the load from 20 N to 40 N. [ABSTRACT FROM AUTHOR]

This study aimed to demonstrate how incorporating titanium dioxide nanoparticles into concrete blocks made with recycled glass mitigates the effects of clogging and surface wear on pavement radiative properties. Using a reference concrete, four variants were formulated: with colourless, green, and amber glass, and a photocatalytic concrete with colourless glass. Three accelerated processes were applied to the concrete blocks in field: clogging, wear, and clogging on a worn surface. After each cycle of clogging and/or wear, solar reflectance and thermal emittance were measured to calculate the solar reflectance index (SRI). Surface clogging decreased the SRI for all concrete types, albeit less for photocatalytic concrete with colourless glass. SRI decreased with wear until a mean texture depth (MTD) near 0.80 mm, where a stabilisation trend was noted across all concretes. Photocatalytic concrete with colourless glass consistently showed the highest SRI values relative to the MTD. Clogging on worn surfaces indicated superior radiative properties for photocatalytic concrete with colourless glass at surface contamination degree (SCD) values less than 40%. In conclusion, conventional concretes with glass had inferior radiative properties compared to reference concrete. However, photocatalytic concrete with colourless glass showed superior radiative properties, indicating that nano-TiO2 addition reduced clogging and wear effects. [ABSTRACT FROM AUTHOR]

The few-layer hexagonal boron nitride (hBN) nanosheets with hydroxyl (−OH) functional group at edges are synthesized using heat treatment of micron size hBN powder followed by sonication. These nanosheets are modified with a silane coupling agent, 3-Aminopropyl,triethoxysilane (APTES). The synthesized hBN nanosheets are mixed with the PP matrix using twin-screw extrusion followed by injection moulding. In case of APTES-modified hBN nanosheets incorporation in the PP matrix with PP-grafted maleic anhydride (PP-g-MA) shows the formation of an imide bond between the MA functional group of PP-g-MA and the amine group of APTES modified hBN nanosheets revealing compatibilization. The flow behaviour index values are lower for hBN nanosheets filled PP nanocomposites showing the improved processability from Rheological characterization. The few-layered – OH and APTES modified hBN nanosheet incorporation in the PP matrix improves the tensile and thermal properties. The incorporation of APTES modified hBN nanosheet in the PP matrix shows an increase in tensile modulus (18.1%) and tensile strength (8.1%) respectively. Wear studies show the incorporation of – OH and APTES modified hBN nanosheets in the PP matrix decreases the coefficient of friction and wear rate significantly. The wear rate at 4 min of wear testing for modified hBN nanosheet in the PP nanocomposites is ~ 96% less in comparison with neat PP. The wear mechanism is established from wear measurements and scanning electron microscopy (SEM) of worn-out wear surfaces of PP nanocomposites. [ABSTRACT FROM AUTHOR]

This study shows that the progressive adhesion of weld material to the tool in friction stir welding AA 2024-T3, up to tool saturation, brings about a decrease in power consumption until a plateau is reached. The cause of this behavior is the hindering of the stirring action of the tool due to the material accumulated on it. The built-up material changes the nature of the tool/material interaction and then the friction condition at their interface. The direct consequence is a decrease in the shearing strain and therefore in the heat generated by friction. Bits of this adhering material break off from the tool at intervals. Macro and micro detachments are identified. Micro-detachments happen continuously at small periodic intervals and produce vibrations. The amplitude of these vibrations increases in all their characteristic spectral components up to tool saturation. Macro-detachments generate oscillations in power consumption and leave galling on the weld bead. [ABSTRACT FROM AUTHOR]

Despite the significant oxidation resistance of NiCrAlY alloy, one of the disadvantages of this alloy is its softness and poor mechanical properties, and low wear resistance. Therefore, in this study, silicon nitride nanoparticles have been used to improve the hardness and wear resistance of the NiCrAlY alloy. The present research has examined the effect of different amounts of Si3N4 nanoparticles (1, 3, and 5 wt.%) on the structure and mechanical properties of NiCrAlY alloy. The samples were characterised by scanning electron microscopy, X-ray diffraction, and Vickers microhardness device. Initially, Si3N4 powders with 1, 3, and 5 wt% were mixed with NiCrAlY powder in a mechanical mill. Next, the powdered mixtures underwent spark plasma sintering (SPS) operations at 1100 °C for 6 min. The results of microhardness measurements showed that adding 1% Si3N4 to NiCrAlY caused the elevation of the hardness from 418 to 614 HV. Further, the sample indicated a wear rate of 1.42 × 10−5 (m3/N.m) at room temperature, under a loading force of 9.8 N, and a sliding length of 500 m. However, with an increase in the weight percentage of Si3N4 in the sample from 1 to 5 wt%, the hardness diminished from 614 to 543 HV. [ABSTRACT FROM AUTHOR]

This research paper focuses on the development of additive-based erosion-resistant high-velocity oxy-fuel (HVOF) WC-10Co4Cr coating for pump steel. In this study, the WC-10Co4Cr cermet powder consists of yttria and zirconia, each with a concentration of 3 wt.%. The HVOF spraying method was utilised to develop the ceramics-added WC-10Co4Cr coatings. The study conducted erosion tests using a pot tester under mining conditions. The microstructure, crystalline phases and microhardness of the as-HVOF coatings were analysed and compared between the pure and ceramics-based WC-10Co4Cr coatings. The results revealed the effect of ceramics addition on surface erosion of WC-10Co4Cr coating. The results indicate that yttrium oxide enhances the performance of WC-10Co4Cr coating in terms of erosion resistance, while zirconium oxide is not suitable for use in WC-10Co4Cr coating in erosion wear environments. [ABSTRACT FROM AUTHOR]

Aluminum alloy being a significant material for many industries, and due to its favourable properties like low density and the high strength-to-weight ratio, is used for cladding. But because of low wear resistance, non-uniform grain structure, and other certain insufficiencies, Friction stir processing (FSP) was applied over the cladded part to overcome these deficits and drawbacks and improve the mechanical characteristics of the produced component further. In this work, mechanical and microstructural characteristics were investigated and analysed by varying rotational speed and number of passes at the time FSP. After FSP finer grains were found, and other solidification defects were eliminated from the final components. Processed part shows the increment in tensile strength, the hardness of the component increases while erosive wear decreases with the number of passes. Maximum hardness and minimum erosion wear rate for all three passes were attained at 598 RPM. Tensile strength and percentage elongation have been found to be highest at three passes at 938 RPM. Microstructure also reflects the finer grains at the highest RPM at the third pass. Also, modern quality management tools and process improvement technique like ANOVA was utilised to formulate the mathematical model and to study the relationship between the input and output of the process. [ABSTRACT FROM AUTHOR]

The Aluminium Metal Matrix Composites are preferred in automotive and aerospace industries for higher strength to weight ratio, good corrosion resistance, and also for better tribological properties. Aluminium improves its qualities by adding reinforcements like fly ash, silicon carbide, tungsten carbide, boron carbide, and ceramic fired bricks. Stir casting is the most common and cost-effective method for processing and creating metal matrix composites, and it is dependent on the processing parameters, reinforcement, and matrix choices. In this investigation stir casting method was used to prepare composites by using Al7475 alloy with preheated reinforced particles of CSA and Graphite. The successful distribution of reinforcements in the Al7475 matrix was confirmed by SEM images of AMMCs and the improved wear and corrosion resistance of AMMC was revealed by the corresponding test results. At 3% Gr and 30N load, the wear rate reduction is 38.4% at 600 rpm, 50.6% at 800 rpm, and 69.4% at 1000 rpm. The highest corrosion rate reduction is possible with 9 % of graphite in CSA composite is 58 %. [ABSTRACT FROM AUTHOR]

In the present work, the reduced graphene oxide (RGO) nanoparticles have been synthesised by modified Hummer's technique. The RGO powder thus obtained was characterised by X-Ray diffraction analysis (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electront microscopy (TEM). Raman spectra showed the D-band at Raman shift of 1354 cm−1 and G-band at 1606 cm−1 of RGO. TEM analysis exhibited the RGO structure in nanometres. The prepared nanoparticles were mixed with alcohol to form a paste and was coated on standard Copper electrode for experimentation on Electric Discharge Machine (EDM). The influence of process parameters like current, pulse on and pulse-off on the material removal rate were studied using L9 Orthogonal Array of Taguchi Technique using Minitab18.0. Substantial improvement in material removal rate at current of 20 amperes, pulse on time of 90 microseconds and pulse off time of 1 microsecond. It was also found that current and pulse off were significant factors that influenced the material removal rate. [ABSTRACT FROM AUTHOR]

Aluminum alloys have advanced to meet the growing demand for strong, lightweight materials. The 2219 aluminum alloy has gained popularity due to its superior mechanical properties and high copper content. However, despite these improvements, the wear characteristics of metal matrix composites with ceramic reinforcements have been suboptimal. This study aims to develop metal matrix composites that improve the mechanical and wear properties of AA2219 aluminum alloy. A homogeneous mixture was created using a 3D mechanical mixer/miller apparatus. ZrO2 and B4C reinforcements were added to the matrix in ratios of 5%, 10%, and 15%, including hybrid composites with both reinforcements. Mechanical and wear characteristics were analyzed, and a 3D profilometer was used to evaluate wear properties and determine tribological parameters. The results showed that the pulverized reinforcement particles were uniformly dispersed within the matrix. The sample with a hybrid reinforcement comprising 15% of the total composition exhibited the highest hardness, measuring 164.96 hV. This study demonstrates that incorporating ceramic reinforcements in specific ratios can significantly enhance the mechanical and wear properties of 2219 aluminum alloy composites. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSThis work implements a 3D finite element to analyze wear in borided AISI 316 L stainless steel. The 3D model was validated through sliding wear test under a ball-on-flat configuration, following the ASTM G133 standard procedures. ABAQUS software was used with an Arbitrary Lagrangian-Eulerian (ALE) remeshing technique alongside the UMESHMOTION subroutine to apply an elemental level Archard’s equation. The artificial roughening of the worn surfaces due to discretization in finite element sizes was controlled by relating the maximum increment time on each wear step to the element size and the stroke. The study also described the evolution of the stress field and the behavior of the contact area. The maximum stress was estimated after the first indentation, decreasing as the contact area increased, reaching a minimum at the last wear step. The results revealed a good correlation between the experimental and modeled data, with a maximum error of 8.34% in the contact stress and a maximum error of 22% in the wear depth.Implementation of a 3D finite element analysis to model wear under ball-on-flat configuration in borided AISI 316 stainless steel.The finite element analysis provides a better understanding about the stress distribution in the selected configuration.Correlation between numerical modeling and experimental data of wear in a borided material. [ABSTRACT FROM AUTHOR]

AbstractThe experimental study assessed the impact of choline chloride cation-based ionic liquid (IL), on the dispersion stability and wear characteristics of copper (II) oxide (CuO) nanoparticles (NPs) in synthetic base oil (PAO 10). CuO NPs, averaging 50 nm in size, underwent surface modification using varying concentrations of the IL (0.25%, 0.5%, 0.75%, and 1% by weight). The formulations were subjected to sliding wear tests to evaluate their wear behavior. Analysis of the worn surfaces utilized scanning electron microscopy, energy-dispersive x-ray spectroscopy, and atomic force microscopy. The results indicated that the combination of 0.75% IL and 1% CuO NPs provided optimal dispersion and exhibited effective surface mending, enhancing wear protection by 21.1% than that of PAO 10. The formulation containing 1% IL and 1% CuO NPs demonstrated the highest load carrying capacity among all tested compositions. In terms of wear behavior, the nanolubricant formulations with 0.75% and 1% IL outperformed the lubricant formulation containing 1 wt% of the commercial antiwear additive Zinc dialkyldithiophosphates (ZDDP). [ABSTRACT FROM AUTHOR]

AbstractThe present study concentrates on the development of carbide-free bainite steel and explores its tribological and mechanical characteristics using a newly devised disk-on-disk tribometer. The microstructure of the treated samples was examined through heat treatment at various holding temperatures (300, 350, and 400 °C) and durations (10, 20, and 30 min), along with isothermal transformation. The wear rate demonstrated significant sensitivity to holding duration, transformation temperature, phase fraction, and the stability of retained austenite. The microstructural analysis encompassed atomic force microscopy (AFM), FE-SEM, x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDS). The study extensively investigated the robust correlation among mechanical properties, microstructure, wear behavior, and the presence of retained austenite (RA) and bainite volume fraction. The findings indicate that carbide-free bainite steel holds promise for replacing conventional railway wheel track steel in the steel industry. The structural property correlations have developed of high silicon steel, hardness reduced with increasing temperature and isothermal preserving time; resulting in a gradual increase in the wear rate of CFB steel. The salt bath soaking temperature of 350 °C with a period of 30 min was found to be the preeminent wear properties condition for CBF steel. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of incorporating Yttria-Stabilized Zirconia (YSZ) and copper (Cu) in the development of Titanium-Based Metal Matrix Composites (TMCs) using the Friction Stir Processing (FSP) technique. The macrostructure of the TMCs, after adding 5% YSZ and 2% Cu, displayed a defect-free, crack-free, and porosity-free surface, indicating the precision of the FSP method. Microstructure analysis revealed a uniform distribution of reinforcement particles and proper dispersion of grains, key for enhancing mechanical properties. The interfacial bonding between titanium and YSZ was exceptionally strong, devoid of cracks and porosity, attributed to the copper additive's role. The increase in the number of grains per square inch for the Ti/5% YSZ/2% Cu composite (1176.26 grains per square inch at 500×) signified finer grain structure, contributing to a remarkable 48.04% improvement in tensile strength compared to pure titanium. The uniform distribution of reinforcement and strong bonding between titanium and YSZ are the driving forces behind the 46.34% increased in hardness. Additionally, the wear resistance of the composite improved by approximately 76.66%, a vital characteristic for applications facing abrasive conditions. The corrosion testing demonstrated an 8.33% enhancement in corrosion resistance with the Ti/5% YSZ/2% Cu composite. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Metallurgical Quarterly is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Metallurgical Quarterly is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Metallurgical Quarterly is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A longevity test was conducted to evaluate the impact of biofuels on engine degradation. Two varieties of blended fuel were generated by adding crude palm oil or crude jatropha oil to B5 diesel. The amounts of additional crude oil were 5, 10, and 15%. The testing period lasted 600 h, which is equivalent to 3–5 years of actual service. Before and after the test, the dimensions of engine elements were measured to determine the level of wear. Inspecting engine components revealed that combining crude bio-oils in proportions ranging from 0 to 15% increased engine wear. Components located in the combustion chamber exhibited greater wear when blended fuels were used, whereas fuel pump and injector components, which were not exposed to the heat, exhibited lower levels of wear. Even though engine wear was observed when mixed fuels were used, the vast majority of wear rates were incredibly low, ranging from 0.001 to 0.002 mm per 100 h. The only exception to this rule was the piston attrition rate, which was measured at 0.007 mm per 100 h. It can be concluded that engine wear is negligible when biofuel is blended with diesel in a ratio not exceeding 15% compared to B5 diesel. Highlights: 600-hour endurance experiments were conducted on diesel engines fueled with biofuel blends. Engine components and fuel supply system were examined for wear. The use of biofuel blended with B5 diesel with no more than 15%, in a diesel engine has no enduring effect. Biofuel blends have the same influence on engine wear as air dust and sulfur. Carbon neutralisation could become a more achievable goal if there is greater confidence in biofuel. [ABSTRACT FROM AUTHOR]

Currently, the majority of industries rely on turning processes to manufacture mechanical products. The selection of coolant is of paramount importance in the pursuit of sustainable manufacturing. Super duplex steel's machinability during the turning process is the subject of the present investigation. The machining characteristics, such as Flank wear (Fw) and Surface roughness (Ra), were analyzed by varying the control parameters, including cutting velocity (Vs), feed rate (f), and cutting conditions i.e. Dry, Nanofluid + MQL (NMQL), LN2 + MQL (LMQL), through a constant depth of cut (d) using a Taguchi L27 orthogonal array. The results demonstrated that the LMQL approach is more efficient as it reduces the Ra by 77%, 54%, and Fw by 83%, and 93%, respectively, in comparison to the dry and NMQL conditions. Additional research on microstructure revealed that the character of the grains is improved when the surface is machined with LMQL in comparison to other cutting conditions. [ABSTRACT FROM AUTHOR]

This work investigates the characterization of a cryo-processed AlTiN-coated tool and its turning characteristics for Inconel 600. The microhardness was enhanced by 3.68% under cryo-treatment when compared with the as-received condition of the inserts because of the wear-protective coating formed on the surfaces of the cutting tool. This was confirmed through EDS elemental analysis of carbon element growth and change in chemical composition, as well as XRD phase analysis. Next, this work studied the influence of cryo-treated inserts on roughness and mechanism of wear during turning Inconel 600 using varying cutting velocities (37, 60, and 100 m/min) under dry conditions. The output responses revealed that the use of cryo-treated tools reduced the roughness of the product by 11–27% and the rate of tool wear when compared with the untreated conditions. Due to these enhanced properties with cryo-treated conditions, it remains a suitable cutting tool for a significant contribution to sustainable machining toward dry cutting of aerospace alloys. [ABSTRACT FROM AUTHOR]

M50 bearing steel is a typical alloy material widely used in aeroengines due to its high hardness and fatigue life at high temperatures. To reveal the frictional mechanisms and wear behaviours of contact and sliding, a molecular dynamics simulation model consisting of an indenter and substrate is constructed. The results indicate that, during the indentation process, the normal load exhibits a linear relationship with the indentation depth at shallow depths. With further penetration, the substrate generates severe deformations and subsurface damages. Throughout the scratching process, the average friction force exhibits a linear increase with the growing scratching depth, while the coefficient of friction decreases. Surface morphologies and shear strain distributions are analyzed to elucidate plastic deformation and atomic displacement. Moreover, the wear atom shows a linear proportionality to both scratching distance and depth. These findings enhance understanding of frictional properties and atomic wear behaviour of M50 bearing steel during contact and sliding, potentially informing bearing failure prediction and material optimization. [ABSTRACT FROM AUTHOR]

The present work involves in a novel approach of studying the material characteristics of AZ31 alloy by varying the cooling method in powder metallurgy and particle size of the matrix material. It also has a novel approach of reinforcing AZ31 alloy with quarry dust and providing self oxide coating to the material in a distinct way for corrosion resistance. The alloy is prepared through powder metallurgy with a pressure of 675 MPa, sintered at 540 ºC, with one hour of soaking. The Scanning Electron Microscopy images are taken to analyse the microstructure. Wear and corrosion studies are done to analyse the effect of parameters. Optimisation for wear is also done with Taguchi method. The AZ31 samples reinforced 5, 10 and 15% of quarry dust are prepared and studied for mechanical properties. The material prepared using 75–150 micron range, cooled in still air cooling and with 5% reinforcement has shown higher values of compressive strength and microhardness. The alloy provided with self-oxide coating has shown higher resistance to corrosion than that of uncoated alloy and the composite. [ABSTRACT FROM AUTHOR]

In this research, the production and wear behavior of CaO and MgO doped stabilized zirconia ceramics prepared by powder metallurgy method were investigated and artificial neural network (ANN) models were established and predicted with the data produced as a result of real experiments. CaO/MgO doped stabilized zirconia ceramics were produced using a combination of ball milling, cold pressing - cold isostatic pressing and sintering methods. CaO and MgO were mixed with zirconia in different amounts (0-8 mol%). These mixtures were prepared by mechanical alloying. Green compacts were sintered at 1600°C. The wear experimental results produced from the trials were converted into data suitable for modelling with ANN. Wear load, wear time of the load, MgO and CaO were given as input to the ANN model. The amount of wear according to the pressing method was set as the output variable value of the ANN. An ANN approach model was established to predict the wear behavior characteristics of zirconia ceramic composites. In order to emphasize the success of the model, the test data set was presented to the ANN model and the results produced were compared with the results produced experimentally, and as a result of these tests, high R2 values of 0.99409 for 65N and 0.97512 for 80N were produced. [ABSTRACT FROM AUTHOR]

Abrupt advancement in technologies lead to growing thirst for efficient and economical alternative materials that possess superior properties. This lead to a gradual shift from the use of monolithic alloys to Metal Matrix Composites (MMCs). High resistance to corrosion and wear makes Aluminium MMC (AMMC) the most promising variant for structural, automotive, marine and aerospace applications. This review opens an insight into the current advancement of AMMCs, detailing an overview on diverse matrices and types of reinforcements that were used to produce such composites. This work also explores and classifies the gain and shortcomings of various phase formations during thermal treatment, revealing the possibilities of improving the physical strength and wear resistance with minimal complexity. This work also highlights the growing concern on corrosion performance of advance AMMC with ceramic reinforcements. In spite of the challenges involved in commercialising AMMC, recent trends of industrial utility reveal their potential to meet evolving demands. [ABSTRACT FROM AUTHOR]

For conformal contact situations, some of the assumptions employed in classical contact theories, such as the flatness of the contact area, lose their validity. Existing conformal contact models are challenged by either accuracy or computational efficiency. With the aim of achieving a balanced trade-off between these contrasting requirements, this paper proposes a new simplified method to solve conformal rolling contact problems, which is based on fast non-Hertzian contact model INFCON and FaStrip. Numerical experiments are performed for two typical wheel/rail conformal contact scenarios to assess the performance of the proposed method, taking as the reference the CONTACT method for conformal contacts. The comparative analyses show that the proposed method is in good agreement with the reference method in terms of the determination of the contact stresses, total forces, and the prediction of wear, whereas the traditional half-space approach fails to capture the main features of the conformal contacts. In addition, the high computational efficiency of the proposed method shows the potential for application in vehicle dynamic simulation and damage analysis. [ABSTRACT FROM AUTHOR]

In the present work, three reinforcement addition techniques such as the slot method (SM), hole method (HM), and zig-zag hole method (ZZHM), are selected to make the hybrid surface composite of AA7075-T651/BN/WC through FSP. The comparative assessment of each method is thoroughly assessed through microstructure, mechanical, and tribological characteristics. Material flow, particle spreading, zone development and phase formation were examined using optical microscopy (OM), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Furthermore, the microhardness and wear characteristics were measured and compared. Based on the findings, ZZHM reveals enhanced material flow and more even particle spreading in the nugget zone than SM and HM. The higher grain refinement and excellent interfacial bonding without any reaction between AA7075-T651 and reinforcement particles (BN and WC) are due to higher DRX and severe plastic deformation (SPD) caused by the tool in ZZHM. The composite made with ZZHM had greater hardness and wear resistance due to the reduction in clusters, even the spreading and lubricating effect of particles and a significant reduction in grain size. This study revealed that the ZZHM is superior to the SM and HM for adding reinforcement and fabricating the hybrid surface composite. [ABSTRACT FROM AUTHOR]

In the present study, we systematically analyze the relationship between the surface microstructural evolution and rolling contact fatigue (RCF) damage behavior of the ER9 wheel tread. In the unfatigued zone (Zone A), where the shear stress was low, a thin plastic deformation layer with low hardness formed. The ferrite grains exhibited obvious plastic flow; however, these grains were not refined, and the cementite showed no significant fragmentation or dissolution. Additionally, the dislocation density remained low on the wheel surface in Zone A. Conversely, in the fatigue zone (Zone B), where the shear stress was high, a thicker plastic deformation layer with increased hardness developed. The ferrite grains in this zone were notably refined, and a substantial amount of lamellar cementite fragmented and dissolved, leading to a high dislocation density on the wheel surface. The severe plastic deformation in Zone B facilitated the formation of fatigue wear cracks on the wheel, which initiated the RCF crack in Zone B. Furthermore, the interface between pearlite and proeutectoid ferrite grains in the wheel accelerated the RCF crack propagation, ultimately leading to RCF failure. [ABSTRACT FROM AUTHOR]

A simple numerical approach is developed to predict the wear and friction of piston ring pack and cylinder liner during the break-in period and under transient speed conditions. In the model, a solution of mixed lubrications using the load-shearing concept is presented based on the selected elastic-plastic equations of asperity contacts in conjunction with well-established elastohydrodynamic equations. The model takes shear-thinning, thermal effects in elastohydrodynamic lubrication (EHL) and lubricant starvation effects into account. Modified Archard's wear coefficient to describe the piston ring against cylinder liner wear is introduced. The approach is valid for the calculations of the asperity pressure at low values of the ratio of oil film thickness to combined roughness of the interacting surfaces, that is, less than 0.5. Applications are discussed, including association of piston side thrust force on wear and friction characteristics of piston ring/cylinder bore, gas blowby through the ring pack on the cylinder liner wear, a strong coating dependence for the piston ring wear, and wear distribution across the stroke under engine operating conditions. A good agreement between the experimental and analytical data indicates that the proposed model can be used to predict the wear and friction of the piston ring pack sliding against cylinder liner. [ABSTRACT FROM AUTHOR]

Due to their low density and exceptional wear resistance, SiCp/Al composites have great potential for brake materials used in trains. In this study, a newly developed SiCp/Al brake disk was fabricated by a powder metallurgy method. The friction and wear behavior of SiCp/Al brakes were investigated under extensive velocity ranges (40–220 km/h) according to the scale conversion rules. It is found that the matching tribocouple exhibits low wear loss, a reliable friction factor, and high heat resistance. The friction film maintains its continuity and stability at high braking speeds and temperatures, effectively protecting the surface of SiCp/Al composite materials from damage, minimizing wear, and stabilizing the friction coefficient. The excellent reliability of the lightweight SiCp/Al brake disk performance confirms its high technical feasibility to replace heavy iron and steel brake disks in urban rail vehicles that normally travel at 220 km/h. [ABSTRACT FROM AUTHOR]

Frictional sliding creates distinct microstructural and chemical discontinuities between the subsurface layer and base materials, which dictate the friction and wear properties. Traditional methods for lowering friction and wear in metals primarily rely on strategies that lower the interfacial shear strength between the contacting discontinuities. Contrary to conventional wisdom, we propose an alternative strategy: introducing tribo-induced or pre-designed heterostructures to suppress tribo-induced strain localization, thus yielding superior tribological properties unachievable with their conventional homogeneous counterparts. Citing recent experimental examples, this review explores the multiscale heterogeneities contributing low friction and wear, by interlinking surface deformation mechanisms and applied tribological conditions. [ABSTRACT FROM AUTHOR]

The current investigation delves into the influence of incorporating bundled multi-layered graphene sheets, specifically multiwalled carbon nanotubes (MWCNTs), on the microstructure, as well as the physical and mechanical attributes of Cu-based nanocomposites. Various weight percentages (1%, 2%, 3%, and 5%) of MWCNTs were infused into the Cu matrix, and the fabrication of these nanocomposites was conducted through the powder technology route. The fabrication process occurred under an argon atmosphere utilizing both conventional sintering and spark plasma sintering (SPS) techniques. The conventionally sintered Cu-based nanocomposite reinforced with 1% MWCNT exhibited the highest relative density (~86%), hardness (~551.12 MPa), compressive strength (~459 MPa), and outstanding resistance to wear. Conversely, the SPS-fabricated nanocomposite reinforced with the same MWCNT concentration demonstrated the highest relative density (approximately 94.25%) and compressive strength (~688 MPa), while the nanocomposite reinforced with 2% MWCNT displayed the highest hardness (~1178 MPa) and resistance to wear. Notably, a higher concentration of MWCNTs was observed to adversely affect the physical, mechanical, and wear properties of the Cu-MWCNT nanocomposites, irrespective of the chosen sintering technique for their production. [ABSTRACT FROM AUTHOR]

Inconel 657, also known as 50Cr-50Ni, is a high-temp, corrosion-resistant Ni-Cr alloy with excellent fuel-ash corrosion resistance against sulfur and vanadium. To make components from Inconel 657, it undergoes casting and machining for dimensional accuracy and surface finish. This study explores the effect of cutting speed on tool wear in turning Inconel 657, focusing on carbide and CBN tools. Higher cutting speeds led to increased flank wear for both tools. Carbide tool wear rose by 16% and 25% at 60 and 120 m/min compared to 30 m/min. CBN tool wear increased by 15%, 29%, and 66% at 120, 250, and 400 m/min compared to 60 m/min. CBN inserts showed 39% less wear than the carbide tool at 60 m/min and 35% less at 120 m/min. Therefore, the carbide tool suits low-speed turning, while the CBN tool is ideal for high-speed machining operations. [ABSTRACT FROM AUTHOR]

Conveyor belts are used for material transportation in the mining and construction industries. The friction and wear properties of the styrene butadiene rubber (SBR) used in conveyor belts are investigated, including the effects of the applied load and rotational speed on the friction coefficient and weight loss. The sliding wear mechanism of the SBR is analyzed using scanning electron microscope, energy dispersive spectrometer, and Fourier transform infrared spectrometer. The results demonstrate that the friction coefficient and total weight loss of SBR increase as a function of rotational speed, whereas the friction coefficient decreases and the total weight loss increases as a function of increasing applied load. The maximum friction coefficient occurred at a loading of 10 N and a speed of 120 revolutions·min−1, and the maximum total weight loss occurred at a loading of 20 N and a speed of 120 revolutions·min−1. In comparison to the unworn surface, the worn surface of the SBR exhibits melting, adhesive, and abrasive wear characteristics. The increases in the hardness, yellowing, oxygen content, and the number of complex structures, such as hydroxyl, aldehyde, ketone, and ether groups, occur simultaneously. [ABSTRACT FROM AUTHOR]

Polymer self-lubricating materials have advantages such as low friction coefficient, good wear resistance, and high work efficiency, giving them wide application potential in friction and wear. This work fabricated polymer-based self-lubricating materials by incorporating oil-loaded mesoporous silica nanoparticles (MSNs + YR1800) in the polypropylene resin (PP). The effects of different content of MSNs + YR1800 on the tribological and mechanical properties of the obtained self-lubricating composite materials were studied. The results indicate that the content of MSNs + YR1800 in composite materials significantly impacts their tribological properties. When the content of MSNs + YR1800 was 10 wt%, the coefficient of friction reduced to 0.09,which was 84.5% lower than for PP and 78.6% lower than for composite materials containing 5 wt% mesoporous silica nanoparticle (MSNs). Compared with pure PP, the wear rate decreases from 4.93 × 10−11 m3∙Nm−1 to 4.43 × 10−13 m3∙Nm−1, which is reduced by two orders of magnitude. The excellent tribological properties of composite materials are attributed to the high specific surface area, large pore volume, strong adsorption capacity, and high oil loading capacity of mesoporous silica nanoparticle as nanofillers. The MSNs + YR1800 release lubricants to form a lubricating oil film during the friction process under load conditions, preventing direct contact between the friction pair and the surface of the composite material. Compared with polymer-silica hybrid oil-loaded microcapsules, MSNs + YR1800 can effectively reduce lubricant leakage, prolong operation life, improve lubrication efficiency, and ensure the continuous and stable existence of lubricating oil films. [ABSTRACT FROM AUTHOR]

This study investigates the influence of cobalt (Co) addition on the microstructural and wear properties of an aluminum (Al) scrap alloy containing high iron (Fe) impurity content (3%). Microstructural analysis using scanning electron microscopy and optical microscopy confirmed the presence of Co in Fe-rich intermetallics. Upon increasing the Co concentration, β-Al5FeSi phase was seen to be refined without significant morphological modifications. Furthermore, Co addition promoted the formation of a new quaternary phase Al32Si7Fe4Co phase, which was finely distributed throughout the microstructure and acts as a tribo-layer in the Al scrap alloy, offering enhanced wear resistance and improved stability against wear. Standard EN-31 steel disk with compositions chromium (Cr)-1.6%, manganese (Mn)-0.75%, silicon (Si)-0.35%, and carbon (C)-0.9% was used for the wear test. Microhardness and wear properties were evaluated for both the as-cast and heat-treated alloys, with the as-cast samples exhibiting superior wear resistance and a lower coefficient of friction compared to the T6 heat-treated samples. Addition of Co showed refinement in the β-Fe rich intermetallics over the morphological modifications. Similarly, Co addition enhanced the hardness and wear resistance in the as cast alloys. This work provides a detailed analysis contributing significant understandings into the wear mechanisms and potential applications of Co modified recycled Al in various industrial sectors. [ABSTRACT FROM AUTHOR]

The tribological behavior of an addendum modified altered tooth sum optimized spur gear set were experimentally compared with that of the standard spur gear under several loading conditions including the wear morphology study and wear debris analysis. The temperature, viscosity, elastohydrodynamic oil film thickness, specific film thickness, and combined surface roughness variation under increasing operating load were analyzed experimentally. Finally, the performance impact of addendum shifted altered tooth sum optimized gear was examined. Results show that the tribological improvement strongly depends on the addendum alteration and modified tooth sum condition. The modification of the addendum in gears with a negatively altered tooth sum facilitates the transition from single-tooth contact to two-tooth contact, broadening the lubrication range while preserving optimal film thickness and improving wear resistance. However, it is reverse to decrease the film thickness and increase wear for standard and profile-modified positively altered tooth sum gear. The gear tribological performance can be significantly improved by profile modification and negatively altered tooth sum approach with a lower rate of degradation of oil and damage on the tooth contacting surface. [ABSTRACT FROM AUTHOR]

This research work was performed to successfully develop a wear-resistant AA7075–SiC composite coating over AA6082 substrate via friction surfacing. For the composite coating deposition, AA7075 consumable rod with micron-sized SiC reinforcement particles filled in the blind holes on its end was considered. The critical process parameters, such as rotational speed (RS) (1000, 1200, and 1400 rpm), number of holes (1, 2, and 3 holes) containing reinforcement and transverse speed (TS) (140, 160, and 180 mm/min) were investigated to determine their influence on the output responses such as microhardness, bond strength and dry sliding wear of the composite coatings. The experiments were planned as per Taguchi's L9 orthogonal array, and the process parameters were multi-optimized using grey relational analysis. The optimized composite coating developed at a RS of 1200 rpm, TS of 140 mm/min, and three holes exhibited a bond strength of 154.72 MPa, improvement in the hardness by 108.7% and reduction in the wear by 56.02% as compared to the substrate. The noteworthy grain refinement in the coating occurred after the addition of SiC microparticles due to the Zener pinning effect. The worn surfaces of the coatings indicated the abrasion and adhesion wear mechanism during the wear testing. [ABSTRACT FROM AUTHOR]

In the present investigation, an Al-18Si-3.6Cu alloy was modified by cerium (Ce), heat treated (T6), and aged for 1, 3, 5, and 7 h at 210°C. The resulting microstructures revealed that the addition of Ce as a modifier changed the morphology of the primary Si from coarse with a sharp edge to spherical, large-acicular/needle-like eutectic Si into a fibrous state, and dendrites of the Al phase into round branches with less interface separation. After thermal ageing, the microstructure of the modified alloy revealed no change in the morphology of the primary Si phase. However, a considerable change in the eutectic Si phase and the formation of fine precipitates of Al2Cu and Al2CeSi intermetallics in the matrix. Hardness was found to be significantly higher in the modified and age-hardened alloys. A Pin-on-disc wear tester was used to investigate the dry sliding wear behavior of alloys at different loads (10, 20, 30, and 40 N) and 1.0 m/s sliding velocity. The results indicated that the wear rate in the modified alloy was lower than the base alloy. Furthermore, the modified alloy after 5 h age hardening demonstrated high wear resistance and improved wear bearing capacity compared to the 1, 3, and 7 h age hardened alloys. [ABSTRACT FROM AUTHOR]

This study studied the tribological properties of PVD AISI 4140 low – alloy TiN coated and reported. The morphologies before testing are assessed with a laser confocal microscope and XRD. Three tests are conducted per sample: the rotating, scratch, and reciprocation tests. The contour of counter bodies and wear scares are studied and reported. The wear scares are also further studied using the SEM-EDS chemical analysis to study the amount of wear that has occurred. The results showed a change in roughness and waviness after coating. In the reciprocating tests showed a high degree of spalling on the TiN sample is observed with a higher wear volume compared to the substrate. However, a lower coefficient of friction is observed. This is similar to the rest of the tests. [ABSTRACT FROM AUTHOR]

In recent years Bio-lubricants much desired in numerous applications in machineries due to their renewable characteristics, which have high biodegradable nature and produce fewer pollutants compared to mineral-based lubricants. Thus, in this paper, the effect of bio-lubricant (Cucurbita Pepo L. seed oil) on wear and friction characteristics in pin on disc tester is studied and compared with commercially available lubricant SAE20W40. Tests were conducted at different loads of 10 N, 50 N, 100 N, 150 N and 200 N at a constant speed of 3 m/s for 60 min to evaluate the behaviour of friction coefficient (COF) and wear at a temperature of 28°C and 100°C. It is observed from the results that, the COF decreases whereas, the wear increases with the rise in temperature and load. Cucurbita pepo L. seed oil (CPO) resulted in a lower wear rate in comparison to commercial SAE20W40. Wear scars on the surface lubricated with SAE20W40 show a rougher surface compared to the pin lubricated with CPO at both lower temperature (28°C) and higher temperature (100°C). This shows that CPO has better lubricity than SAE20W40. The present work indicates that CPO can be a possible substitute to mineral-based lubricant SAE20W40 for higher-temperature workplaces. [ABSTRACT FROM AUTHOR]

The tribological simulation can be seen as a new study problem developed through modern information technology and computer simulation technology in combination with a variety of mathematical approaches in the field of tribology. There is a need to seek new conducts and means of in-depth study of the wear quantitative law, or else, it will become difficult for a fundamental breakthrough in the prevention and control of wear to be achieved. The tribological simulation research of the typical Pin-on-Disc sliding wear test system has been carried out by the adoption of computer technology and mathematical analysis methods to provide a new wear-analysis method for the simulation of the basic tribological contact problems. In the present research conduct, an attempt has been made to establish the wear simulation model considering multiple parameters based on experimental and theoretical facts. The parameters of the computational model have been determined through the experimental test data. The simulation model has been observed to reflect the basic relationship between input and output of the pin on the dry disc sliding wear test. Experiments performed have confirmed that, under the conditions analysed, the load effect on the wear rate is more critical than the other conditions. The wear rate varies linearly with the considered load conditions. The simulations have been conducted at the different angular velocities of 50, 60 and 70 rpm. These simulations have also revealed the effect of pin diameter on the depth of wear, and the deep insight into the increase of same with an increase in surface area. [ABSTRACT FROM AUTHOR]

High-pressure grinding rolls (HPGR) have increased their popularity in the minerals industry, since their first application in the 1980s for raw material preparation in the cement industry. Recent advances on the technology have been responsible for putting it in a prominent position among comminution processes, with applications that now range from tertiary crushing stages to pressing iron ore concentrates prior to pelletization. This work reviews some of the recent advances in the technology applied to the minerals industry, including efforts toward improvement on roll lifetime, understanding the effect of progressive roll surface wear on machine performance, alternative lateral confinement systems, the phenomenon of skewing and entirely novel machine designs. Such advances, besides recent insights into the equipment operation, are analyzed, whenever possible, with the assistance of advanced simulation tools, in particular, the discrete element method (DEM). [ABSTRACT FROM AUTHOR]

To increase vehicle dynamics modelling accuracy in simulation environments, in this work, we propose a model, where the mutual influence of the vehicle dynamics and tyre wear is taken into account. In this context, simulation-oriented models aim at representing the main features of the vehicle dynamics, while keeping the complexity low, making them suitable for control-oriented analyses and design. The wear model quantifies tyre wear as a tyre mass loss depending on the tyre-road interaction, derived from the vehicle dynamics and kinematics; then, the outcome of this model is consequently used to update the tyre friction characteristics, by modifying the main parameters of the Pacejka's magic formula. We also discuss the steps required to use the model in two-wheeled vehicles, where the roll dynamics plays an important role in the tyre wear. The main features of the developed model are discussed on a motorcycle, as a simulation case-study. [ABSTRACT FROM AUTHOR]

The influence of homogenization and quench-aging treatments on the dry sliding friction and wear behavior of Al-40Zn-3Cu bearing alloy was experimentally studied. These treatments removed dendritic structure of the alloy and caused the formation of zinc-rich precipitates distributed homogenously in the matrix of the alloy. It was observed that quench-aging treatment carried out at temperatures of 100 °C and 150 °C significantly improved both hardness and strength of the alloy as compared to homogenization treatment. However, aging at 200 °C lowered these values of the alloy but increased its elongation. Dry sliding wear test results displayed that homogenization and quench-aging treatments increased the wear performance of the alloy. However, it is found that the quench-aging treatment created more powerful effect for improving wear performance of the alloy than homogenization. Quench-aging treatment at 100 °C for 300 min resulted in a decrease in the lowest specific wear rate of the alloy by causing the highest increases in its hardness (from 119 HB to 178 HB), yield strength (from 288 MPa to 383 MPa) and tensile strength (from 319 MPa to 407 MPa) due to the age hardening mechanism. It was observed that the worn surfaces of the alloy samples were composed of adhered and smeared material and delaminated areas. This observation suggested that adhesion and delamination were the operative wear mechanisms of the alloy. The results were explained and discussed in terms of microstructural features, mechanical properties, and wear mechanisms of Al-40Zn-3Cu alloy. [ABSTRACT FROM AUTHOR]

AbstractBruxism can be defined as the process of direct contact with teeth and dental materials with an involuntary jaw-tightening movement. In this process, teeth and dental materials can be exposed to various damage mechanisms. This study aims to realize the mechanism of bruxism with finite element analysis and in vitro rotating chewing movement analysis. Within the scope of the study, cp-Ti, Ti-5Zr, and Ti-5Ta materials were subjected to wear tests in the finite element analysis and in vitro rotating chewing movement method under the determined Bruxism chewing test conditions. Test specimens with cylindrical geometry were exposed to a direct every-contact wear mechanism for 30 s under 150 N bruxism chewing bite force. The bruxism chewing cycle continued for 300 min at a frequency of 2 Hz. Microanalysis of the wear surfaces of the samples after the experimental study was carried out with Scanning Electron Microscopy. The results obtained within the scope of this study showed that the Bruxism wear resistance increased by adding zirconium and tantalum to pure titanium material. This result shows that pure titanium material, which is known to have poor wear resistance, can be improved with Zr and Ta alloys. It is clinically important that the success rate in the treatment process increases with the increase in wear resistance. However, the micro-cracks observed in the microstructure may have occurred in the sub-surface, which is a show of the fatigue wear mechanism. [ABSTRACT FROM AUTHOR]

High Velocity Oxygen Fuel (HVOF) process enables superior properties and is foreseen as a suitable candidate for deposition of hard chromium alternative coatings over the other surface hardening techniques like cladding/deposition through electrolysis/CVD methods, owing to the widespread adaptability and preference in aerospace industry, in particular landing gear mechanism and associated modules that operating in severe environments encountering abrasion, erosion, sliding and fretting wear. Cermet coatings are very often utilised to intensify the wear and corrosion resistance of a wide range of engineering components. The objective of this work is to develop thermally sprayable oxides, nitrides and carbides of WC and Cr3C2 cermet coatings on AISI 4340 steel by HVOF technique. The modified surface is characterised by SEM/EDAX study, followed by the evaluation of Porosity and Microhardness of the modified different speeds and loads. The study unveiled that of all the stated coatings, the blend of WC-Co-VC matrix yields superior hardness, Coefficient of friction and lower order of porosity. The observation forefronts the enhancement of wear properties in terms of surpassing wear resistance and declining trend in volume loss compared to other compositions. [ABSTRACT FROM AUTHOR]

This research aims to create a composite that is inexpensive and can be used in mechanical applications. The main aim is to improve the tribological performance of PA66 by reinforcements. Two fillers were utilised in the experimentation because MoS2 is a remarkably effective solid lubricant in dry conditions, but the results are not the same in high humidity. H-BN is utilised here to get the benefit in both dry and humid environments and to reduce the negative impact of humidity on the tribological performance of composite. Tensile and hardness tests were performed to identify the mechanical properties, while tribological tests on pin-on-disc were performed to analyse the COF and wear rates of materials. SEM, XRD, and DSC characterisations were utilised to analyse the tensile fracture mechanism, crystallinity, and glass-transition temperature of materials, respectively. The result shows that the strength and hardness of the composite increased in a reasonable amount compared to virgin PA66. Wear and COF tests were conducted with three different parameters, and the results showed an improvement in wear rates of composites compared to virgin PA66. [ABSTRACT FROM AUTHOR]