High Friction Coefficient Research Articles

Unravelling seismogenesis and characterizing the unique features of two significant felt earthquakes (M > 4.0) of 2020 in the southwestern parts of the Delhi region

Two significant earthquakes (M4.6 and 4.2) occurred close to a NE–SW-trending lineament in the southwestern part of the Delhi NCR (National Capital Region) within a short time span of about 5 months in 2020. These events were located to the north of the Alwar district in Rajasthan and generated a significant ground shaking in and around Delhi. In the present study, we tried to understand a causal relationship between the events and a nearby source in the region, geologically demarcated as the lineament. We analyzed the broadband waveform data from 26 seismic stations that recorded the recent events of 03 July 2020 (M4.6) and 17 December 2020 (M4.2). Typically, the epicentral area has been devoid of significant earthquakes since the past six decades; however, a few minor events (M < 4.0) have been recorded till date. Analysis of the earthquake database for two decades (2000–2022) revealed low seismicity (nearly quiescent-like situation) in ∼100 sq km area around the epicentral zone, unlike considerable seismicity along faults/lineaments close to the Delhi region. The full-waveform inversion analyses of the events indicate normal faulting with a minor strike–slip components. The source parameters, viz., source radius, stress drop, and seismic moment, were estimated to be 6 km, 166 bars, and 8.28E+15 Nm, respectively, for the 03 July 2020 event and 4 km, 138 bars, and 2.29E+15 Nm, respectively, for the 17 December 2020 event. The causative source of these events is ascertained based on the stress inversion modeling that indicated a NW–SE tensile stress corroborating well with the NE–SW-trending lineament mapped in the study region. The static Coulomb stress modeling indicated that the event which occurred on 3 July 2020 had advanced the triggering process of the event in the northeast segment of the same source that occurred on 17 December 2020. We further emphasize that the aforementioned lineament probably activated due to the regional tectonics of the study area. The causative source of these events with strike 48°, dip 86°, and rake −60° is found to be in the conformity with the local tectonics and is well-supplemented by a high stress ratio (0.70 ± 0.05) and low friction coefficient (0.5).

Characterization of surface properties of TiC ceramic coating developed on AISI 1020 steel

The aim of this research was to develop the TiC ceramic coating on the AISI 1020 steel substrate by a tungsten inert gas cladding (TIG) process and to comprehensively assess the surface properties of deposited TiC coatings. Various TIG currents were employed to deposit the TiC coating. The study included a detailed investigation of the two pivotal aspects: wear rate and microhardness. Additionally, a comprehensive examination of the microstructure and the presence of different phases in the coating layers was done. TiC ceramics were found to be dispersed remarkably and uniformly over the whole coating region, as revealed by scanning electron microscopy (SEM) examinations. Additionally, it was noted that neither the coating area nor the interfacial areas included any harmful flaws like voids or cracks. The results of this experiment clearly showed that the processing current and the subsequent wear resistance and microhardness were directly correlated. In particular, it was shown that wear resistance and microhardness both showed a noticeable increase when the processing current decreased. The coating developed at lower proceeding current 80 A found the most remarkable results, achieving a peak microhardness of 2846 HV0.1 and an impressively low wear rate of only 10.96 × 10−8 g/Nm. These extraordinary results can be directly attributable to the hard TiC phase's significant presence inside the coatings layer. Due to its improved wear behaviour and microhardness as compared to untreated mild steel, pure TiC-coated AISI 1020 steel finds a suitable material for application in wear-resistance components where hardness is considered as a crucial factor. The TiC coating has achieved an exceptionally high friction coefficient, making it particularly valuable for applications within the automobile industry.

Combining laser surface texturing and double glow plasma surface chromizing to improve tribological performance of Ti6Al4V alloy

Ti6Al4V (TC4) alloy has been widely applied in the military, industrial, chemical, and medical fields due to their excellent thermal stability, corrosion resistance, and biocompatibility. However, titanium alloys are notorious for their poor tribological properties, such as their high friction coefficients and low surface bearing capacities. To tackle this problem, combination of laser surface texturing (LST) and double glow plasma chromizing was conducted to improve the wear resistance of TC4. LST was first conducted to produce uniform dimples with a diameter of 300 μm and gradient density of 11 % on the Ti6Al4V substrate. A chromizing coating (Cr-coating) was subsequently deposited on the surfaces of the textured and raw Ti6Al4V alloy by double glow plasma surface alloying (DGPSA). A continuous and compact Cr-coating with a thickness of about 55 μm was formed on TC4 after being maintained at a temperature of 850 °C, and the coating was mainly composed of a solid solution and intermetallic compounds of Cr2Ti phases. The surface hardness after alloying was two times higher than that of the TC4 substrate. Comparative assessments on the wear resistance of the Cr-coatings with and without LST treatment and the TC4 alloy were carried out using a ball-on-disk wear tester. The results showed that the mass loss and specific wear rate of the duplex-treated sample were 1.54 mg and 7.14 × 10−4 mm3·N−1·m−1. The mass loss and specific wear rate of the TC4 were 4.32 mg and 1.62 × 10−3 mm3·N−1·m−1. The specific wear rates of the four tested samples were in the following order: the duplex-treated TC4 < textured TC4 < chromized TC4 < polished TC4. The coating obtained by LST-double glow plasma chromizing duplex treatment exhibited an outstanding durability and the best mechanical performance. Thus, this approach be used for the protection of Ti6Al4V surface in engineering components and medical instruments.

Tribological behavior of electroless Ni-B ternary and quaternary coatings with inclusion of W and Mo

Electroless nickel coatings help to tailor requisite surface properties in materials for use in various applications. The aim of the present study is to examine the tribological behavior of electroless nickel-boron coatings incorporated with Mo and W. The coated layers are developed over pin samples with various bath compositions. The coated specimens are characterised to assess their basic features. The tribological tests are carried out with the help of a pin-on-disc tribo-tester under dry conditions. The coating characteristics are determined to comprehend the importance of tungsten as well as molybdenum concentration in electroless nickel-boron coatings. In the as-deposited state, all the coated specimens displayed a surface morphology resembling cauliflower. Moreover, the roughness of these coated surfaces in their as-deposited state showed an increase corresponding to the concentration of the bath parameter, resulting in a higher coefficient of friction (COF). The addition of Mo into Ni-B matrix promotes the coarse grained and cracked surface morphology leading to highest friction coefficient value of as-deposited Ni-B-Mo coatings. The highest surface roughness of Ni-B-Mo coatings also leads to the highest specific wear rate due to breaking and crushing of roughness peaks. The present study reveals the effect of incorporation of W and Mo in electroless Ni-B coatings to control the friction and wear characteristics of the specimens. This will help in deciding the proper electroless bath compositions for specific tribological applications.

Effects of sp3 bond ratio and modulation ratios on nanotribology behaviors of diamond-like carbon coatings investigated using atomistic nanoscratching simulations.

Diamond-like carbon (DLC) films are amorphous solids in which carbon atoms are linked by hybridized sp3, sp2, and sp bonds. The mechanical and tribological properties of DLC films can be adjusted by tuning the sp2/sp3 bond ratio. These films are typically used as protective coatings for components such as dies, automotive engines, mechanical seals, hard disk drives, biological engineering devices, and micro/nano-electromechanical systems. Further exploration of the mechanical and tribological behavior of DLC films is important for enhancing functional design for the above applications. The simulation results show that single-layer DLC with a higher sp3 ratio has better resistance to indentation. Single-layer DLC with a lower initial sp3 ratio has lower friction and a shorter repeated cycle in the friction force curve due to an increase in the graphitization of the friction interface. Single-layer DLC with a higher sp3 ratio has a higher coefficient of friction because compared with the normal force, the friction force is much more sensitive to an increase in the sp3 ratio. Molecular dynamics simulations based on the Tersoff potential were performed using the open-source code LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator).

An investigation on the performance of vehicle brake pads developed from Cortaderia selloana based biomass

AbstractNowadays, researchers are making intense efforts to develop biomass-based industrial products. This study developed low-metallic and asbestos-free samples based on Cortaderia selloana (12–15% and 18% ratios), a natural species, to contribute to the brake pad field. The developed samples’ friction coefficient and wear rate experiments were carried out on a brake pad test device with a load of 1 MPa and a disk rotation speed of 6 m/s, according to the TS555 standard. Scanning electron microscopy and electron-dispersive x-ray analysis were performed on the worn surfaces of the samples. According to the results obtained, the wear rate increased while the average friction coefficient decreased in the brake pad samples using 18% Cortaderia selloana content in the sample content. In scanning electron microscopy analysis, primary and secondary plateau formations were observed on the worn surfaces of all samples. At the same time, samples containing 15% and 18% Cortaderia selloana also showed signs of abrasive wear. High friction coefficient and low wear rate are expected for brake pads to be used in automobiles. In general, the friction of brake pads must be within the range, and it is always necessary to balance the friction to avoid driver discomfort. However, except for some racing applications, a high coefficient of friction is only sometimes desirable, which can cause rotor wear problems. As a result of this research, a consistent friction coefficient and low wear rate for the brake pads with the brake pad sample containing 12% Cortaderia selloana.

Analysis of Tribology Properties of Trimethylolpropane-based Lubricant by Molecular Dynamics.

Currently, it is crucial for the lubricant formulation industry to explore cost-effective and environmentally friendly methodologies for analyzing the tribological properties of engine aviation lubricants under high-temperature and high-pressure operating conditions. This study demonstrates the feasibility of employing molecular dynamic simulations to gain essential insights into the evolution of the tribological properties of lubricants during operation. A three-layer molecular model was devised, comprising nickel aluminide molecules in the top and bottom layers, and polyol ester in the core. The impact of sliding velocities ranging from 20 km/h to 100 km/h was investigated under varying temperature and pressure conditions. Concentration, temperature and velocity profiles, radial distribution function, mean square displacement, and friction coefficient were calculated and analyzed in detail. Notably, the highest friction coefficients - ranging from 2.5 to 0.75 - were observed at the lowest temperature and pressure conditions tested. Conversely, other sections of the gas turbine exhibited substantially lower friction coefficients - ranging from 0 to 0.01.Simulations demonstrate that increasing pressure and temperature reduce polymer chain mobility, leading to stronger internal interactions within the lubricant. Consequently, lubricant adsorption onto metal surfaces decreases. Furthermore, the lubricant performs exceptionally well when its molecules encounter higher velocities and temperatures. Based on the results obtained, the research demonstrates that the presented technique provides both quantitative and qualitative tribological information essential for understanding a system molecular behavior, serving as a guiding framework for researchers in the field.

Features of changes in adhesiveand tribological characteristics of multilayer coatings (TiZrNbYAl)N

In this work, the adhesive and tribological characteristics of (TiZrNbYAl)N multilayer coatings were studied. The main goal of this work is to assess the influence of the number of layers on the adhesive and tribological characteristics of the (TiZrNbYAl)N coating deposited on 12Х18Н9Т steel substrates. A study of the distribution of elements over the depth of coatings using Auger electron spectroscopy showed that chemical elements are distributed quite evenly over the cross section of the coatings and the element distribution curves have sharp peaks. The presence of iron in the coating composition at a depth of more than 2 microns on the coating side indicates that an increase in electrical displacement ensures reliable adhesion of the coating to the steel substrate, which is confirmed by the results of testing the coatings for adhesive strength. An increase in the application time of each individual layer at Upp=-100 V and P= 4×10-3 Torr leads to an uneven distribution of elements throughout the thickness of the coatings and the formation of a relatively wide transition coating-substrate layer. Tests of the adhesive strength of coatings have shown that all coatings wear out when scratched, but do not peel off, i.e., they are destroyed by a cohesive mechanism associated with plastic deformation and the formation of fatigue cracks in the coating material. Different coating modes correspond to different values of acoustic emission depending on the load. It was determined that the coatings obtained at Upp =-100 V; P = 4×10-3 Torr showed high adhesive strength and some degree of delamination in the scratch area at the maximum test load. The results of tribological studies showed that (TiZrNbYAl)N coatings have a high friction coefficient, the average value of which is μ=0.85-0.95. Such values can be explained by the high roughness of wear tracks due to cohesive destruction of coatings.

Carbon-carbon composite material in friction units when lubricated with hydraulic fluid

The paper deals with the issues related to the friction of carbon-carbon composite against steel in the medium of hydraulic fluid. Variation of friction coefficient from load, speed and temperature is analyzed. Comparison of antifriction properties of Hardcarb TP material with fluoroplastic modified by radiation treatment is performed. It is established that under the conditions of the experiments, the carbon composite has a higher friction coefficient than the fluoroplastic, but acceptable (f = 0.12) for use in friction units. Hardcarb TP material is promising for application in sliding friction friction units in lubrication with AMg-10 working fluid under conditions of increased requirements for the reliability and service life of hydraulic pumps.

Mechanical characterization of soundproofed inclined screws connections

Timber structures are susceptible to sound propagation problems. The issue can be mitigated by decoupling structural components at connections level by means of polyurethane soundproofing interlayers. These layers are much softer than timber but, at the same time, they are characterized by higher friction coefficients. In this paper, an experimental investigation is carried out to characterize the mechanical behavior of insulated screw connections assessing the implications of the soundproofing layer use. Different interlayers, screw inclination angles and setups are considered. The load–slip behavior is studied, and a proper empirical model, suitable for performing push-over analysis of buildings involving soundproofed connections, is derived. The essential design parameters, namely the slip modulus, the strength and ductility, are determined and compared with existing models predictions, thus testing their accuracy. Substantial reductions in terms of stiffness, load-carrying capacity and ductility are observed in soundproofed connections.

Yüksek Silisli Lamel Grafit Dökme Demir Kamyon Fren Disklerinin Sürtünme ve Aşınma Davranışı

In this study, the chemical compositions of high-silicon lamellar graphite cast irons commonly used in truck brake discs and the effects of applied heat treatments on their friction and wear behaviors were investigated. For this purpose, samples with two different chemical compositions (first with 2.43 C and 4.5 Si; second with 2.5 C and 4.2 Si) were produced, and homogenization annealing was applied at 900°C for 30, 45, and 60 minutes followed by air cooling. Hardness, tensile testing, and wear testing were performed on the heat-treated samples. Wear tests were conducted at room temperature and dry sliding conditions (20 N load, 250 mm sliding distance, and 200 mm/min sliding speed) using a ball-on-disk wear apparatus against 52100 bearing steel. The increase in homogenization heat treatment time resulted in an increase in hardness and tensile strength values for both lamellar graphite cast iron grades. The wear test results indicated that both the chemical composition and the duration of applied heat treatment influenced the friction coefficient and wear volume losses. Since high friction coefficient and low wear volume losses are desired in brake discs, it was determined that the best result among the compared samples was achieved in the sample produced with a chemical composition of 2.5 C and 4.2 Si, and then homogenized at 900°C for 30 minutes.

Composition, structure, and wear resistance of (TiZrNbMoTa)CxN1-x high entropy alloy carbonitride coatings prepared by reactive radio-frequency magnetron sputtering

HEN has high hardness and good toughness but a high coefficient of friction and poor wear resistance. In this study, a high hardness, toughness, and wear-resistant HECxN1-x coating was prepared by reactive radio-frequency magnetron sputtering (RFMS) technology. The phase composition, microstructure, mechanical properties, and tribological properties of the HEN and HECxN1-x coatings were investigated. The results show that all coatings have single-phase rock salt structures. The double anion lattice structure of the HECxN1-x coating produces a high lattice distortion effect and grain refinement effect, which realizes the strengthening and hardening of the coating. When the [C]/([C] + [N]) ratio is 0.3, the hardness of the HECxN1-x coating reaches the maximum value of 41.7GPa, and when the [C]/([C] + [N]) ratio is 0.4, the coating toughness reaches the maximum value of 0.91GPa, which are 48 % and 203 % higher than HEN. The self-lubricating effect of supersaturated precipitated amorphous carbon makes the HECxN1-x coating achieve excellent tribological properties. Among them, HEC0.5N0.5 coating has the best tribological properties, its coefficient of friction (COF) is 0.391, which is 148 % lower than that of HEN coating, and the wear rate is reduced to 1/15 of HEN coating, which is one order of magnitude reduction. Introducing the C element based on HEN can effectively solve the problems of high friction coefficient and poor wear resistance of high entropy nitride ceramic coatings.

Oxidation differences on Si- versus C-terminated surfaces of SiC during planarization in the fabrication of high-power, high-frequency semiconductor device

Silicon carbide (SiC) wafers have attracted attention as a material for advanced power semiconductor device applications due to their high bandgap and stability at high temperatures and voltages. However, the inherent chemical and mechanical stability of SiC poses significant challenges in the chemical mechanical planarization (CMP) process, an essential step in reducing defects and improving surface flatness. SiC exhibits different mechanical and chemical properties depending on SiC terminal faces, affecting SiC oxidation behavior during the CMP process. Here, we investigate the process of oxide layer formation during the CMP process and how it relates to the SiC terminal faces. The results show that under the same conditions, the C-terminated face (C-face) exhibits higher oxidation reaction kinetics than the Si-terminated face (Si-face), forming an oxide layer of finer particles. Due to the different oxidation kinetic tendencies, the oxide layer formed on the C-face has a higher friction coefficient and more defects than the oxide layer formed on the Si-face. This results in a higher removal rate during CMP for the C-face than the Si-face. Furthermore, by controlling the physicochemical properties of the oxide film, high removal rates can be achieved by friction with the pad alone, without the need for nanoparticle abrasives.

CATHODIC PLASMA ELECTROLYTIC DEPOSITION (CPED) TECHNIQUE FOR SURFACE STRENGTHENING OF TITANIUM AND TITANIUM ALLOYS: A MINI REVIEW

Due to the unique properties of titanium (Ti) and its alloys, it has a particularly wide range of applications in aerospace, automotive, medical and other fields. However, the problems of low surface hardness, high friction coefficient and low wear resistance of Ti alloys limit its development to a certain extent. The destruction of Ti and its alloys often occurs on the surface of materials such as wear damage, corrosion, and oxidation resistance. Therefore, the exploration and application of surface strengthening technology is particularly important. The cathodic plasma electrolytic deposition (CPED) technology, as a surface modification technology, can achieve better adhesion and facilitate the material to achieve better comprehensive performance. This paper briefly introduces the basic concepts, principles and development progress of CPED. Starting from the preparation of ceramic coatings, metal coatings, diamond-like carbon films and composite coatings, it summarizes the application of CPED in Ti and its alloys. Applications in alloys to improve thermal oxidation resistance, wear resistance, corrosion resistance, and film-based adhesion. At the end, its development in the new era environment is prospected.

Structure and tribological properties of multiphase carbon coatings fabricated by multi-arc ion plating

Carbon coating with excellent wear resistance will play a significant role in protecting metal materials, especially in piston rings. In this work, a series of multiphase carbon coatings were fabricated by multi-arc ion plating under different bias voltages ranging from 0 to 160 V. The microstructures were investigated by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Raman Spectroscopy and X-ray Photoelectron Spectrometry (XPS). The mechanical properties and tribological performances were measured by nanoindentation, scratching tester and reciprocating tribometer. The results demonstrated that the multiphase carbon coatings mainly compose different phases, including amorphous carbon, fullerene-like carbon, nanographite, nanodiamond and C60. The sp2 hybrid bond existed in the form of multi-bent carbon rings and increased from 46.82 % to 52.01 % with the increase of bias voltage. The content of seven-membered carbon rings (7A1) increased first and then decreased, with the highest value of 18.05 %. The hardness values of the coatings ranged from 18.33 ± 3.55 GPa to 33.88 ± 2.26 GPa. When Vickers indenter was pressed into the coating under high load, the coating exhibited good load strength and toughness. Under the load of 10 N, the friction coefficient between the coating and Φ3 mm 316 stainless steel (SS) balls in fresh 5 W-30 oil was about 0.13. In the degraded oil, the highest friction coefficient was 0.20, and the lowest was 0.11. The grinding ball's surface looked to have sustained severe damage, but there was no visible damage to the coating structure at the worn tracks. There was no significant difference in the coating surface profile curves before and after rubbing exhibiting super wear resistance of coatings.

Preparation and Tribological Properties of Self‐Lubricating Epoxy Resin Composites with Oil‐Containing Carbon‐Based Nanocapsules

Oil‐containing nanocapsules are prepared and used to solve the challenges arising from the low mechanical properties and high coefficient of friction (CoF) of epoxy resin (EP). The shell of the nanocapsules is amorphous carbon and the core is lubricating oil (ATF6, Automatic Transmission Fluid 6). The nanocapsules are uniform hollow spheres with an average particle diameter of 530 nm and a shell thickness of 60 nm. The mass content of the lubricating oil encapsulated in the nanocapsules can reach 64.88% upon vacuum impregnation. Enhancing with the oil‐containing nanocapsules, the tribological properties of EP composites are studied in detail. Compared with those of neat EP, the compressive strength of the EP composite with 7 vol% nanocapsules improves by 9.2%, and the CoF and wear rate reduce by 71.70% and 89.38%, respectively. During the friction process, the oil‐containing nanocapsules are crushed and the oil is released, which contributes to the antifriction property of EP composites. Moreover, the results are expected to open up new ideas for the research and development of self‐lubricating materials.

Control of the tribological temperature dependence of hydrogenated amorphous carbon films by doping with W

While numerous strategies have been developed to enhance the high-temperature performance of amorphous carbon films, challenges persist regarding high coefficients of friction and wear rates within the mid-temperature range (200–300 °C). In this study, we developed a series of a-C:H(W) films with varying tungsten concentrations and systematically investigated their wear and friction characteristics using Al2O3 ceramic balls at different temperatures. The results reveal that the a-C:H(W) film (W3) with a WC target current of 0.3 A exhibits friction coefficients of 0.10 and 0.06 at 300 °C and 500 °C, respectively. The addition of hydrogen to the film enables stable lubrication in the intermediate temperature range. The presence of carbide facilitates the formation of a continuous protective layer during friction at 500 °C. Additionally, the inclusion of tungsten trioxide effectively reduces friction during high-temperature lubrication. Overall, this a-C:H(W) film shows promise in addressing the challenges of high-temperature wear in mechanical engineering applications under harsh operating conditions.

Effect of Cu addition on the tribological properties and oxidation behavior of nanomultilayered AlTiN/Cu coatings

As a soft metal, the addition of Cu has an important influence on the high-temperature tribological properties and oxidation behavior of nanomultilayered AlTiN/Cu coatings. At room temperature (RT), due to abrasive wear, the AlTiN coating exhibited a high friction coefficient of 0.97 and low wear resistance. After adding Cu layer, the friction coefficient gradually decreased to 0.59 at 18.4 at.% Cu due to the lubricating effect of soft metal Cu and CuO, and the best wear resistance was achieved at 2.9 at.% Cu. At 800 °C, the oxidation resistance sharply reduced after adding Cu layer, and exhibited oxidation delamination. At low Cu contents (≤4.5 at.%), by the inward diffusion of O, a mixed oxide layer of Al2O3, TiO2, and CuO formed. At 18.4 at.% Cu, by the outward diffusion and oxidation of Cu, double-layer oxides formed, and the top layer of CuO contributed to a low friction coefficient of 0.53, but also caused a reduce in the wear resistance.

Pathways of Water-Induced Lead-Halide Perovskite Surface Degradation: Insights from In Situ Atomic-Scale Analysis.

While organic-inorganic hybrid perovskites are emerging as promising materials for next-generation photovoltaic applications, the origins and pathways of perovskite instability remain speculative. In particular, the degradation of perovskite surfaces by ambient water is a crucial subject for determining the long-term viability of perovskite-based solar cells. Here, we conducted surface characterization and atomic-scale analysis of the reaction mechanisms for methylammonium lead bromide (MA(CH3NH3)PbBr3) single crystals using ambient-pressure atomic force microscopy (AP-AFM) and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) in environments ranging from ultrahigh vacuum to 0.01 mbar of water vapor. MAPbBr3 single crystals, grown by a solution process, were mechanically cleaved under UHV conditions to obtain an atomically clean surface. Consecutive topography and friction force measurements in low-pressure water (pwater ≈ 10-5 mbar) revealed the formation of degraded patches, one atomic layer deep, gradually increasing their coverage until the surface was entirely covered at a water exposure of 4.7 × 104 langmuir (L). At the perimeters of these degraded patches, a higher friction coefficient was observed, along with an interstitial step height, which we attribute to a structure equivalent to that of the MA-Br terminated surface. Combined with NAP-XPS analysis, our results demonstrate that water vapor induces the dissociation of surface methylammonium ligands, eventually resulting in the depletion of the surface MA and the full coverage of hydrocarbon species after exposure to 0.01 mbar of water vapor.

A molecular dynamics study of 3C‐SiC/epoxy nanocomposite as a metal‐free friction material

AbstractThe tribological, mechanical, and thermal properties of an epoxy crosslinking network incorporated with 3C‐SiC nanoparticles, serving as a metal‐free friction material were investigated by molecular dynamics simulations. The considered models encompass pure epoxy materials with 35%, 50%, 65%, and 80% crosslinking degrees, as well as 3C‐SiC/epoxy composite materials at the same crosslinking levels. Glass transition temperature (Tg) of the eight models was analyzed, and the result shows augmenting crosslinking density and addition of 3C‐SiC nanofillers improve Tg of all models. Fractional free volume of each model was quantified to reflect the features of epoxy materials and influence the properties at the atomic scale. Frictional force, normal force, and coefficient of friction (COF) were calculated to elucidate the tribological performance of the epoxy‐based materials. The introduction of 3C‐SiC nanofillers reduces COF. With nanofillers, higher crosslinking degree brings lower COF except 80% crosslinking degree, while without nanofillers, higher COFs are obtained with 35% and 80% crosslinking degrees. 3C‐SiC/epoxy composite with heightened crosslinking degree demonstrates superior Young's modulus, elevated tensile stress, and relatively smaller strain. Thermal conductivity analysis highlights the positive impact of both increased crosslinking density and incorporation of 3C‐SiC nanofillers on heat transfer. Temperature elevation further enhances thermal conductivity.