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The environment is a very important topic today as well as in the future. One source of air pollution that has the potential to harm health is the wear particles released by vehicle braking systems. If these wear particles come from hazardous materials, they could destroy human health and the environment. Based on these conditions, exploring more environmentally friendly materials to substitute hazardous materials as friction materials is necessary. In this study, brake linings were prepared from bamboo fiber and eggshell (ES) particles with various pre-treatment conditions. The composition of the material frictions consisted of phenolic resin, bamboo fiber, bamboo particles, ES particles, zinc, alumina, and graphite in the following: 35% phenolic resin, 10% graphite, 10% bamboo fiber, 10% alumina powder, 5% zinc powder, and 30% bamboo particles and ESs. This study focused on observing the mechanical and tribological behavior of friction materials when using ES particles as fillers. There are three stages to manufacturing friction material: a cold press, a hot press, and heat treatment. The optimization of the characteristics of ESs as organic brake linings was carried out using the Taguchi method and analyzed using data envelopment analysis-based ranking (DEAR). An interesting finding from this study was that when ES particles were calcined at 900°C for 120 min, the ES particle size was 200 mesh, and the ES volume fraction at 25% resulted in the most optimal brake lining performance. Calcination at 900°C for 120 min completely changed the CaCO3 phase to CaO. This study also shows that calcined ES particles have the potential to be developed as friction materials for environmentally friendly two-wheeled vehicles in the future. The produced brake linings exhibited hardness, a coefficient of friction, and specific wear rates of 92.82 HR, 0.32, and 4.43 × 10−6 mm3·N−1·m−1, respectively.

This research aims to assess the mechanical characteristics of high-performance copper composites made utilizing powder metallurgy. The composites were produced by adding reinforcement elements (Al2O3-Cr3C2) at different rates (3-6–9 wt.%) into copper-graphite (Cu-5Gr) via hot pressing technique. The microstructure, hardness, three-point bending and wear performance were analysed. The results determined that hybrid reinforced composites exhibited higher density, hardness and bending strength compared to Cu-Gr composites. The highest hardness of 73.02 HB was found in the CG-4 (copper graphit-4) sample. The maximum bending stress of 151.06 MPa occurred in sample CG-2. In addition, it was observed that the wear resistance increased significantly with the addition of the hybrid reinforcements. The lowest specific wear rate of 7.961 × 10−7 mm3/N.m occurred in sample CG-6. As a result, 15.92%, 58.16% and 83.21% improvements were achieved in hardness, bending strength and wear performance, respectively. The current work indicates that certain mechanical properties of copper can be improved via the powder metallurgy process and the addition of reinforcements which could expand the applications and use of this metal in different industries. [ABSTRACT FROM AUTHOR]

Ni-Cr-B-Si hardface coating plays an important role in the mating components of nuclear power plants. Obtaining a crack-free coating with low dilution and optimum hardness is essential for reactor applications. In general, it is difficult to achieve this through conventional high heat input processes. In this work, Ni-Cr-B-Si hardface coating was successfully developed on 316LN stainless steel substrate by Cold Metal Transfer (CMT) welding process using metal-cored filler wire. Moreover, for comparative analysis, Ni-Cr-B-Si hardface coating was deposited using Plasma Transferred Arc (PTA) process. The obtained coatings were characterised for their microstructure, hardness, and wear behaviour. Results revealed higher hardness and lower specific wear rate of hardface coating made by the CMT process compared to the coating made by the PTA process. The superior behaviour of the CMT coating obtained may be due to its low dilution compared to the coating made using the PTA process. Confocal microscopy on the worn pins revealed abrasive and adhesive wear as a dominant mechanism in the CMT and PTA coatings, respectively. This study concluded that CMT could be used as an alternate potential process for depositing a crack-free hardface coating with superior wear behaviour. [ABSTRACT FROM AUTHOR]

Bronze metal matrix composites (MMCs) are futuristic materials that may find applications in automobile, aviation, and marine industries, specifically for propellers in submarines, bearings, and bushings for defence purposes. The present investigation studied the effect of Si3N4 (5, 10, 15 wt%) ceramic particles on the physical, metallurgical, and tribological behaviour of Cu-10Sn/Si3N4 MMCs. Cast rods of three composites and a base alloy were fabricated using the liquid metallurgy route. The microstructural characterisation for the cast samples was conducted using FESEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), XRD (X-ray diffraction), and TEM (Transmission Electron Microscope), which revealed that the Cu-10Sn alloy reinforced with 5 wt% of Si3N4 had homogeneous distribution and perfect bonding of the Si3N4 with the bronze MMC. The dry sliding wear test was performed by varying parameters such as the applied load (10, 20, 30 N) and sliding velocity (1, 2, 3 m/s). The specific wear rate (SWR) increased against an increased load. However, the SWR and coefficient of friction decreased and then increased against an increasing sliding velocity due to tribolayer formation. The primary wear mechanism observed at low and high loads was severe delamination. In contrast, the wear mechanism was adhesion wear at high and low velocities. Amongst the researched samples, Cu-10Sn/5 wt% Si3N4 composites revealed the least SWR at a load of 10 N and sliding velocity of 2 m/s and hence can be recommended for manufacturing bearings and bushings in the automobile and defence industry. [ABSTRACT FROM AUTHOR]

Because of their high thermal conductivity, good corrosion resistance, and great mechanical qualities, copper matrix composites are appealing materials utilized in a variety of industries. This study investigates the mechanical properties of copper–graphite (Cu–Gr) matrix composites reinforced with silicon carbide (SiC) and tungsten carbide (WC) particles by hot pressing using powder metallurgy method. The goal is to investigate the influence of the reinforcement ratio on the mechanical characteristics of copper composite materials generated (density, hardness, flexural strength, and wear resistance). SEM, EDS, and X-RD analysis were used to perform metallographic examinations. The highest relative density with a value of 98.558% was determined in the C3 sample. The findings revealed that when the reinforcement ratio was raised, the hardness rose. The highest hardness value was observed in the C6 sample with an increase of 12.52%. Sample C4 (with the lowest SiC and WC particles ratio) had the highest bending stress (233.18 MPa). Bending stress increased by 35.56% compared to the C1 sample. The lowest specific wear rates were found in the C4 sample, with a decrease of 82.57% compared to the C1 sample. The lowest wear rate (6.853 × 10−7 mm3/Nm) also occurred in the C4 sample. The microstructural analysis showed that the hybrid reinforcement particles exhibited a homogeneous distribution in the copper matrix. X-RD analysis showed that there was no intermediate reaction between the parent matrix and the hybrid reinforcements. A good interfacial bond was observed between the matrix structure and the hybrid reinforcements. The motivation of this research was to utilise the advantages of the unique features of SiC–WC hybrid particles to improve the performance of newly developed Cu-6Gr composites for wear-resistance applications. [ABSTRACT FROM AUTHOR]

This paper investigated the tribological behavior of natural fiber-reinforced polyester composites. The Cyperus pangorei (CP) fiber and polyester were used as a reinforcement material and thermosetting matrix, respectively. The composites were fabricated using compression molding technique with 40 wt% of CP fiber. Technological properties such as density, hardness, and wear of the composite specimens were determined. The density and shore D hardness of the prepared specimens were 1.0176 g/cc ± 0.106 and 87.25 ± 4.1, respectively. A pin-on-disk wear test machine was used to conduct the dry sliding wear test with constant sliding distance; various sliding velocities of 1, 2, and 3 m/s; and a range of contact pressure of 0.13–0.38 MPa. After the wear test, the surface roughness of worn specimens was measured. The specific wear rate increased when the applied load was increased on the specimen. A non-linear decrease in coefficient of friction was observed with the combination of increasing contact pressure and decreasing sliding velocity. The morphological analyses were carried out using a scanning electron microscope for the worn specimens.

Bronze metal matrix composites (MMCs) are futuristic materials that may find applications in automobile, aviation, and marine industries, specifically for propellers in submarines, bearings, and bushings for defence purposes. The present investigation studied the effect of Si3N4 (5, 10, 15 wt%) ceramic particles on the physical, metallurgical, and tribological behaviour of Cu-10Sn/Si3N4 MMCs. Cast rods of three composites and a base alloy were fabricated using the liquid metallurgy route. The microstructural characterisation for the cast samples was conducted using FESEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), XRD (X-ray diffraction), and TEM (Transmission Electron Microscope), which revealed that the Cu-10Sn alloy reinforced with 5 wt% of Si3N4 had homogeneous distribution and perfect bonding of the Si3N4 with the bronze MMC. The dry sliding wear test was performed by varying parameters such as the applied load (10, 20, 30 N) and sliding velocity (1, 2, 3 m/s). The specific wear rate (SWR) increased against an increased load. However, the SWR and coefficient of friction decreased and then increased against an increasing sliding velocity due to tribolayer formation. The primary wear mechanism observed at low and high loads was severe delamination. In contrast, the wear mechanism was adhesion wear at high and low velocities. Amongst the researched samples, Cu-10Sn/5 wt% Si3N4 composites revealed the least SWR at a load of 10 N and sliding velocity of 2 m/s and hence can be recommended for manufacturing bearings and bushings in the automobile and defence industry.

In the present investigation nano basalt epoxy composites have been examined for its possibility in employing new wear resistant material with improved friction and thermo mechanical characteristics. The nanocomposites were fabricated by dispersing (1–5 wt.%) nano basalt particles in epoxy using sonication process. The density, mechanical properties (tensile strength and micro hardness), thermal stability along with friction and wear behavior have been investigated as per ASTM standard. The result shows that all the properties found to be increased with nano basalt content in the thermosetting epoxy matrix. The FESEM studies reveal the homogeneous dispersion of nano basalt (≤3 wt.%) in the epoxy matrix. This uniform dispersion improves the thermomechanical and friction characteristics. The specific wear rate of the nano epoxy composites reinforced with nano basalt particulates exhibits the superior wear-resistance properties. The results reveal that 3 wt.% nano basalt in the epoxy matrix yields maximum improvement in tensile strength, micro hardness, thermal stability, wear resistance and coefficient of friction when compared to other composites subjected to investigation. The excessive addition (>3 wt.%) forms basalt clusters as agglomeration which pull down the frictional and thermo mechanical performance. [ABSTRACT FROM AUTHOR]

Because of their high thermal conductivity, good corrosion resistance, and great mechanical qualities, copper matrix composites are appealing materials utilized in a variety of industries. This study investigates the mechanical properties of copper–graphite (Cu–Gr) matrix composites reinforced with silicon carbide (SiC) and tungsten carbide (WC) particles by hot pressing using powder metallurgy method. The goal is to investigate the influence of the reinforcement ratio on the mechanical characteristics of copper composite materials generated (density, hardness, flexural strength, and wear resistance). SEM, EDS, and X-RD analysis were used to perform metallographic examinations. The highest relative density with a value of 98.558% was determined in the C3 sample. The findings revealed that when the reinforcement ratio was raised, the hardness rose. The highest hardness value was observed in the C6 sample with an increase of 12.52%. Sample C4 (with the lowest SiC and WC particles ratio) had the highest bending stress (233.18 MPa). Bending stress increased by 35.56% compared to the C1 sample. The lowest specific wear rates were found in the C4 sample, with a decrease of 82.57% compared to the C1 sample. The lowest wear rate (6.853 × 10−7 mm3/Nm) also occurred in the C4 sample. The microstructural analysis showed that the hybrid reinforcement particles exhibited a homogeneous distribution in the copper matrix. X-RD analysis showed that there was no intermediate reaction between the parent matrix and the hybrid reinforcements. A good interfacial bond was observed between the matrix structure and the hybrid reinforcements. The motivation of this research was to utilise the advantages of the unique features of SiC–WC hybrid particles to improve the performance of newly developed Cu-6Gr composites for wear-resistance applications.

This paper investigated the tribological behavior of natural fiber-reinforced polyester composites. The Cyperus pangorei (CP) fiber and polyester were used as a reinforcement material and thermosetting matrix, respectively. The composites were fabricated using compression molding technique with 40 wt% of CP fiber. Technological properties such as density, hardness, and wear of the composite specimens were determined. The density and shore D hardness of the prepared specimens were 1.0176 g/cc ± 0.106 and 87.25 ± 4.1, respectively. A pin-on-disk wear test machine was used to conduct the dry sliding wear test with constant sliding distance; various sliding velocities of 1, 2, and 3 m/s; and a range of contact pressure of 0.13–0.38 MPa. After the wear test, the surface roughness of worn specimens was measured. The specific wear rate increased when the applied load was increased on the specimen. A non-linear decrease in coefficient of friction was observed with the combination of increasing contact pressure and decreasing sliding velocity. The morphological analyses were carried out using a scanning electron microscope for the worn specimens. [ABSTRACT FROM AUTHOR]

To develop TiB 2 –TiN–SiC and TiB 2 –TiN–SiC-hBN based ceramic matrix composite coatings with superior mechanical and tribological properties suitable for engineering applications, a high-power CW-laser is used to initiate chemical reactions in precursor powder mixtures (TiO 2 , SiO 2 , hBN and graphite) of several compositions preplaced over AISI1025 steel substrates. Here, coatings' stoichiometric compositions (TiB 2 –TiN–SiC) fabricated through in-situ synthesis are altered by adding SiC and additional amount hBN in the precursor at variable weight ratios. Presence of variable amount of SiC in TiB 2 –TiN–SiC and hBN in TiB 2 –TiN–SiC-hBN composites imparts several microstructural, mechanical and tribological property combinations. In this study, an attempt has been made to experimentally evaluate the optimum range of hBN and SiC additions to obtain highest improvements in lubrication and wear resistance respectively. [ABSTRACT FROM AUTHOR]

Polyamide 66 has been recently used in mechanical applications especially in gears manufacturing due to their low weight, low cost, and good tribological characteristics. In particular, great attention must be considered on the specific wear rate for polyamide 66 and their composites under dry sliding conditions. The goal of this paper is to study the effect of wear parameters; applied load, sliding distance and thermal effects on specific wear rate for neat polyamide 66 and their composites after adding 1% wt CNT or 30% wt (CF) under dry sliding conditions as well as, study the effect of the reinforcement materials on the hardness and their relationship to specific wear rate. The experimental result shows that the increase in wear parameters leads to increase the specific wear rate. However, with the addition of 1% wt CNT or 30% wt (CF) increasing the wear resistance by 130% and 200% under (30N) applied load and by 107% and 144% under (4000m) sliding distance respectively. Moreover, significant increase in hardness explained the enhancement in wear resistance. A scanning electron microscopy was done for the harmed specimen surfaces and the images appeared that the addition of reinforcement materials gives smooth surfaces with little harm unlike neat polyamide 66. [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]

TiC based cermets have been prepared with three different grades of stainless steel binder (304L, 316L and 410L). The cermets were densified by vacuum melt infiltration, at 1500 °C, which allows the steel binder content to be readily varied from 5 to 30 vol%. The cermets were assessed for their hardness and indentation fracture resistance using Vickers testing. The reciprocating wear response was evaluated using a ball on flat geometry, with a WC-Co counter face sphere. It was shown that the coefficient of friction increases with increasing steel binder content, and also with increasing load and wear time. Similarly, the specific wear rate increases with both steel binder content and applied load, but was largely independent of the steel grade used. [ABSTRACT FROM AUTHOR]

We consider the influence of alumina (AlO) particles on mechanical and tribological properties of aluminum hybrid metal matrix composites (MMC). Various weight fraction of AlO (5, 10 and 15%) and constant weight fraction of graphite (5%) were used to fabricate composites by stir casting method. The effect of AlO content on hardness, density and specific wear rate is evaluated. A wear test was performed using central composite design matrix on a pin-on disc apparatus at room temperature for constant sliding distance of 1000 m. The sliding speed, load and weight fraction of AlO were the process variables. The results show that the hardness and density increase with increase in AlO content. From the analysis of variance (ANOVA), load is the dominant factor that affects the specific wear rate of hybrid composites followed by speed and weight fraction of AlO. Based on desirability approach, the improvement in the wear resistance of the composites became more prominent at high speed, high load and high weight fraction of AlO. The worn surface of the pin was examined using scanning electron microscope (SEM) which indicates that the wear mechanism of composites is mostly abrasive wear followed by oxide wear. [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]