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Highlights Unique hybrid thermoplastic composites based on polyoxymethylene copolymer (POM C), 10 wt.% glass fiber (GF) and graphite (Grt) filler at 1, 3, and 5 wt.% were developed using injection molding technique. According to the Taguchi L16 orthogonal array, present experiments were carried out with the aim of determining the coefficient of friction (COF) and specific wear rate (SWR) under a range of loads (namely, 5, 10, 20, and 30 N), sliding speeds (namely, 200, 400, 600, and 800 rpm), and run times (namely, 15, 30, 45, and 60 min) with varying wt.% of Grt (namely, 1, 3, and 5 wt.%) throughout the experiment. Analysis of variance (ANOVA) was used to evaluate the most significant factors that affect the output functions (viz., COF and SWR). The findings demonstrated that POM C/10GF composites' tribo‐mechanical, structural, and thermal properties were considerably improved upon by including Grt. Various microscopical methods were also employed to study the wear mechanisms of the composites and the surface morphology of the worn samples. The POM C/10GF with a 3 wt.% of Grt exhibited superior tribological properties owing to its enhanced interfacial bonding characteristics, resulting to increased wear resistance. Injection molded POM C/10GF hybrid composites with 1, 3, and 5 wt.% graphite (Grt) Structural, thermal, chemical, tribo‐mechanical and microstructural studies Design of experiment with variable loads, times, speeds, and Grt compositions COF and specific wear resistance as response Optimization of hybrid composite composition using Taguchi L16 orthogonal array [ABSTRACT FROM AUTHOR]

To enhance the friction performance of resin‐based friction materials, five types of specimens with different polymer ether ketone (PEEK) contents were fabricated and their physiomechanical behaviours were tested and, their tribological properties were investigated using a JF150F‐II constant‐speed tester. It was found that the addition of PEEK had a positive influence on the properties of the friction materials, and sample FM‐3 (the shorthand of 'Friction Materials‐3', containing 2 wt% PEEK) exhibited improved friction performance with a fade ratio and recovery ratio of 8.6% and 101.1% respectively. Among all samples, FM‐4 (the shorthand of 'Friction Materials‐4', containing 3 wt% PEEK) had the lowest specific wear rate with a value of 0.622 × 10−7 cm3 (N·m)−1 at 350°C. The PEEK can fill the microcracks in the composite at a high temperature and can also cover the hard abrasive particles to prevent them from directly damaging the composite. The findings from this study afford a foundation for studies to further improve the properties of resin‐based friction materials. [ABSTRACT FROM AUTHOR]

Scientists are working on the development of materials and lubricants to reduce friction as well as wear at metalto-metal interfaces having relative motion. Aluminum is a widely used metal due to its high strength to weight ratio and availability in nature as compared to other metals that are manufactured by the rolling process. The output of the product quality and quantity from the rolling process requires less energy as compared to other manufacturing processes. A tribological study has been carried at the in-situ condition for the interface of Al6061 and steel EN31 on the pin on disc setup. To analyze the effectiveness of lubricant with mating surfaces, the effect of rolling lubricant was analyzed for tribological behavior and compared with the dry condition. The coefficient of friction was reduced up to 80% and the specific wear rate was reduced up to 96% by using rolling lubricant compared to dry conditions at the interface of metals that had relative motion. [ABSTRACT FROM AUTHOR]

Interesting mechanical and tribological properties, favorable for both ambient and high temperature applications, can be gathered by composites consisting of multiple reinforcing phases. The present study focuses on the characterization of ceramic matrix composite coatings with in-situ reinforcements, developed through combination of laser triggered chemical reaction and subsequent laser treatment. A preplaced precursor mixture of TiO 2 , SiO 2 , hBN and graphite powders in stoichiometric proportions is used for the chemical reaction activated by a high power laser beam to produce coatings containing TiB 2 , TiN, SiC and hBN. Minor modifications in the constituents of the preplaced precursor mixture helped in developing coatings different in terms of the amount of hBN and SiC present in it. This compositional variation brought significant changes in mechanical and tribological properties of the coatings. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) are used to confirm the presence of all the reaction products in the CMC coatings developed. Evaluation of nanomechanical properties and studies on the tribological properties of these coatings are performed thoroughly. Reduced modulus (E r ) and nanohardness (H) of the composite coatings deposited on AISI 1025 steel have been measured from load–displacement curves. The stress-strain curves of composite coatings help in characterizing its damage tolerance and determining design stresses to find suitability to any application. Presence of hBN in composite coating causes reduction in coefficient of friction. Coatings formed with SiC in precursor helps in improving the specific wear rate. Top surface morphology and tribological properties of these coatings, after they are exposed to high temperature, are also explored. [ABSTRACT FROM AUTHOR]

Recent advances in polymer nanocomposites open a wide range of applications in various industrial sectors. Due to their high potential properties, these materials are replacing the usage of metals for many heavier components in automobile industries. In this experimental work, the tribological performance of Graphene oxide (GO) - Polyamide is investigated against pristine polyamide by fabricating gears for the usage in engineering applications. A gear test rig was developed in-house for analysis to study the specific wear rate and temperature gradient at different conditions of load and speeds. The wear resistance of the polyamide gears with the addition of 0.03wt.% of graphene oxide is better than the pristine polyamide gears and the specific wear rate is reduced significantly. The reduced specific wear rate of these polymer nanocomposite gears is attributed to the superior properties of graphene oxide such as High specific surface area, good adhesion properties and enhanced glass transition temperatures. The GO nanocomposite gear seems to be a potential alternative against conventional gears for engineering applications. Finally, the wear mechanisms and the potential of GO-based polyamide nanocomposite gears were proposed tentatively in the development of transmission gears for engineering applications. [ABSTRACT FROM AUTHOR]

This paper analyses the influence of graphite reinforcement, load and sliding speed with constant sliding distance on tribological behavior of A356 aluminum matrix composites reinforced with 10 wt.% silicon carbide and graphite using the Taguchi design. Hybrid composites were produced in the compo-casting process. Tribological tests were performed on a block-on-disc tribometer where the weight percentage of graphite has three variations (0, 3, and 5), as well as load (10 N, 20 N, and 30 N) and sliding speed (0.25 m/s, 0.5 m/s, and 1 m/s), with sliding distance of 300 m. The wear of the composite is investigated under dry sliding condition. The specific wear rate was analyzed using Taguchi method with the aim of finding the optimal parameters. By applying analysis of variance, it was determined that the best tribological properties has A356/10SiC/3Gr hybrid composite. It was also found that the greatest impact on specific wear rate has load with the percentage effect of 69.163%, then sliding speed with 14.426% and the interaction between wt.% graphite and load. The dominant wear mechanism is adhesive wear as confirmed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). [ABSTRACT FROM AUTHOR]

ABSTRACT The study aims for potential utilization of red mud (an industrial waste) to be utilized as a wear-resistant material. Investigations on mechanical and wear characteristics of red mud epoxy based homogeneous and their functionally graded materials (FGMs) developed with an intent of probable application in tribological systems are presented. The influence of significant operational parameters, material parameters, and their subsequent influences among themselves are explored. A specially designed experimental series is performed on a pin-on-disk machine with three different sliding velocities 105, 209, and 314 cm/s under three different loading conditions of 20, 30, and 40 N and compares the experimental results with the reported theoretical wear model. Artificial neural network approach is also applied to the wear data for subsequent validation. The comparative study indicates that although the homogeneous composites and FGMs exhibit relatively inferior mechanical properties, the sliding wear performance of the FGMs is better than homogeneous composites. It is also found that out of all synthesized composites FGMs exhibit the maximum impact strength and tensile modulus, which clearly indicates that the gradation achieved because the centrifugation technique enhances the crack arresting capability of the materials. The measured Young's moduli of homogeneous composites and FGMs were compared to standard theoretical prediction models. The measured moduli values showed good harmony with those predicted from Halpin-Tsai and Kerner models. Transmission electron microscopy microstructures confirm the continuous graded dispersion of red mud particles in the matrix. [ABSTRACT FROM AUTHOR]

Abstract: The production of Ni3Al was performed under an uniaxial pressure of 150MPa at 1050°C for 1h. The formation temperature of Ni3Al was determined to be 655°C. The presence of Ni3Al was confirmed by XRD analysis. SEM analysis revealed that the Ni3Al phase has very low porosity. The relative density and microhardness of test materials were 97.8% and about 359±31HV1.0, respectively. The specific wear rate of Ni3Al was 0.029mm3/Nm for 2N, 0.017mm3/Nm for 5N and 0.011mm3/Nm for 10N, respectively. The distribution of alloying elements was determined by energy-dispersive spectroscopy (EDS). [Copyright &y& Elsevier]

Present work deals with the experimental investigation of tribological properties of GF-filled polymer composites considering three velocities, i.e. 0.5, 1 and 2.0 m/s and loads ranging from 15.7 N to 45.13 N keeping rest of the parameters constant. The test has been carried out for three materials, PTFE + 15% GF, PTFE + 25% GF and PTFE + 35% GF in wet (oil) and adding additive as graphite (5% wt) in oil. SAE 20W40 oil is used for the test. Friction and wear tests of PTFE composite against a counter surface of EN8 with surface finish of 0.56 μm are carried out at ambient conditions using pin-on-disc tribometre (TR-20), Ducom make, Bangalore. The results are tabulated and graphs are plotted. It has been found that load and wet conditions have significant effect on coefficient of friction and specific wear rate of the materials. Where as sliding velocity also plays little role in wear mechanism of the material. It is concluded from the experimental study that the specific wear rate in wet condition as well as by adding additives in lubricating oil with 5% (by wt.) has been declined. Also the specific wear rate decreases with normal load and sliding velocity. Wear of PTFE + GF composite decreases with increase in glass percentage. Microscopic analysis of pin and disc surface is made with optical microscope. The mathematical models has been developed by using regression analysis and found to be valid for the above tested parameters. [ABSTRACT FROM AUTHOR]

Abstract: Friction coefficients and specific wear rates of an existed Ni3Al-based NAC-alloy with composition of Ni–18.8Al–10.7Fe–0.5Mn–0.5Ti–0.2B (at.%) and its composites reinforced by 6vol.% Cr3C2- and 6vol.% MnS-particles, respectively were investigated for the initial understanding of sliding wear behaviors of the materials under unlubricated condition. The testing materials were prepared by hot isostatic pressing (HIP) process. Pin-on-Disk (POD) measurements were carried out under room temperature condition. A commercial vermicular graphite cast iron was selected as a reference material. The disks used in this study were made of a grey cast iron as cylinder liner materials of ship engines. The contact pressure of 2.83MPa and 5.66MPa were applied in POD tests. The experimental results revealed that the monolithic NAC-alloy has the almost same values of friction coefficient and specific wear rate under the testing condition as compared to a commercial vermicular cast iron. The wear mechanism is probably conducted to its intrinsic deformation mechanism of the Ni3Al-type of intermetallics. For the composite with 6vol.% hard Cr3C2-particle, wear rate was reduced on both sides of pin and disk up to 50%, comparing to the single phase NAC-alloy at a high load of 5.66MPa. By an addition of 6vol.% soft MnS-particle, wear rate of the disk was dramatically decreased and friction coefficient also slightly reduced on the test. But, the wear rate of pin is maintaining as the same level as the monolithic NAC-alloy and the reference vermicular cast iron. The present investigation recognized that it will be potential to develop Ni3Al-matrix composites reinforced by hard Cr3C2- and/or soft MnS-particles for a certain tribological applications, especially other excellent physical, chemical and mechanical properties of the Ni3Al-based intermetallic materials were considered. [Copyright &y& Elsevier]

The surface characteristics of polymers play an important role in unlubricated sliding applications that involve a polymer-metal interface because they are relatively softer than most metals. In this article, roller burnishing is introduced as a technique to improve the friction and wear characteristic of polymers in such applications. The polymers used in this study are polyoxymethylene (POM) as a thermoplastic polymer and polyurethane (PUR) as a thermosetting polymer. The combination of moderate values of burnishing force and speed is recommended during burnishing operations. The lowest surface roughness value, Ra, achieved for POM is 0.53 μm (32% decrease) and for PUR is 0.57 μm (29% decrease). The tribological behavior of the burnished polymers is found to be predominantly related to their surface quality. The lowest coefficient of friction value achieved in this work for POM is 0.24 (26.8% decrease) for POM and for PUR it is 0.27 (17.7% decrease). The lowest specific wear rate achieved in this work for POM is 0.37 × 10-6 mm3/Nm (27.8% decrease) and for PUR it is 0.47 × 10-6 mm3/Nm (25.2% decrease). These findings show that the roller burnishing process has the capability to improve the surface quality and tribological characteristics of POM and PUR. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we studied and explored the tribological performance of pure vinylester (V), glass fiber reinforced (GFR), SiC filled glass fiber reinforced vinylester composite under dry and water lubricated sliding conditions. Friction and wear tests were carried out with configuration of a pin on a rotating disc under ambient conditions. Tests were conducted at normal load 10, 30 and 50N and under sliding speed of 1.6m/s, 2.8m/s and 4m/s. The results showed that the coefficient of friction decreases with the increase in applied normal load values both under dry and water lubricated conditions. On the other hand for pure vinylester specific wear rate increases with increase in applied normal load under dry sliding condition and decreases with increase in applied normal load under water lubricated conditions. However the specific wear rate for GFR vinylester composite and SiC filled GFR vinylester composite decreases with the increase in applied normal load both under dry and water lubricated conditions. Moreover, for the range of load and speeds used in this investigation the coefficient of friction and specific wear rates using water lubricant registered lower values than that of the dry condition. The specific wear rates for pure vinylester and vinylester+50wt.% GFR and SiC filled GFR vinylester composite under dry and water lubricated sliding condition were in the order of 10−7 mm3 N−1 mm−1. [Copyright &y& Elsevier]

Abstract: Clay – thermoset polyester nanocomposites and conventional clay filled composites are produced using organo-modified clay as the reinforcement and unmodified inorganic clay as filler, respectively. Composites are prepared with clay contents of 1wt.%, 3wt.% and 5wt.%. Tribological property of the nanocomposite system is studied to assess the influence of nanoclay and compared with conventional clay filled composites. The wear test is carried out on a pin-on-disc tribometer with the composite pin sliding over a disc made of tool steel. The coefficient of friction and wear loss decreases significantly on addition of organoclay, whereas for conventional clay filled composites wear loss and coefficient of friction increases with increase in inorganic clay content. The nanocomposites exhibit a maximum of 85% improvement in wear resistance and 35% decrease in coefficient of friction. The highest wear resistant and least coefficient of friction is observed in the nanocomposite with a clay content of 3wt.%. [Copyright &y& Elsevier]

In order to determine the wear properties of AIP(Arc Ion Plating) deposition, wear process was evaluated by using a Falex test machine. Also, in order to determine the effects of coating material on the wear process, TiC, TiN, and TiCN coatings of thickness about 5 μrn — 6 μm coated by Arc ion plating deposition method were tested. The wear property was determined under a dry sliding condition as a function of the applied load, sliding distance, sliding velocity and temperature. The results show that when wear of the coating-layer occurred, specific wear amount increased with the wear rate. At initial state, the wear rate rapidly increased, but it gradually reduced as the velocity increased. Also, when raising the temperature, the wear rate increased in the order of TiCN, TiN and TiC due to the frictional heat. [ABSTRACT FROM AUTHOR]