Steel Counterface Research Articles

Growth and morphology of thermally assisted sinterable zirconia nanoparticle tribofilm

Tribofilm formation mechanisms of a novel zirconia (ZrO2) nanoparticle antiwear additive were investigated. Spherical ZrO2 nanoparticles 5 nm in diameter with organic capping ligands were dispersed in a polyalphaolefin (PAO) synthetic base oil and tested between AISI 52100 steel counterfaces in a ball-on-disk tribometer under boundary lubrication contact conditions. Film formation was studied as a function of temperature, using PAO blends to maintain constant viscosity across the different temperatures. A temperature dependence was found, with higher temperatures assisting initial tribofilm growth and maintaining the steady-state tribofilm thickness. Findings are consistent with previous reports indicating the primary mechanism of tribofilm growth for zirconium oxide is nanoparticle capture at the sliding interface followed by particle accumulation and sintering.

Insights into the microstructure characteristics, mechanical properties and tribological behaviour of gas-phase chromized coating on GCr15 bearing steel

In this study, a high quality chromized coating was produced on GCr15 steel substrate by vapor phase chromizing technique for sprag clutch application. The microstructure characteristics, mechanical properties and sliding friction behaviour were systematically investigated. The results show that the chromized coating consists of 1) an outmost layer of columnar Cr7C3 grains with excess carbon atoms (55 at.%) and considerable amount of iron atoms (6.2 at.%); and 2) an inner layer of coarse Fe3C grains. The carbide phase formation can be well explained via the thermodynamics evaluation for the Fe-Cr-C system, while the origin of carbon contamination is likely originated from the side reactions of precursor gases. The high surface hardness (16.6 GPa) and interfacial adhesion (~50 N) endow the chromized coatings with superior wear resistance against steel counterface under ambient conditions. The wear rates are found to decrease with the applied load (10–25 N). Scanning electron microscopy (SEM) analysis of the worn surfaces indicates that a chromium oxide tribolayer tends to be formed under a higher loading which displays lubrication and hence protects the contacting material during the friction process.

Probing lubricated sliding wear properties of HDPE/UHMWPE hybrid bionanocomposite.

Ultra-high molecular weight polyethylene (UHMWPE) and its derivatives have been clinically used as an acetabular liner material in total hip joint replacement (THR) over last six decades. Despite significant efforts, the longevity of UHMWPE implants is still impaired due to their compromised tribological performance, leading to osteolysis and aseptic loosening. The present study aims to critically evaluate and analyze the tribological performance, of the next generation acetabular liner material, that is, a chemically modified graphene oxide (GO) reinforced HDPE/UHMWPE (HU) bionanocomposite (HUmGO), against stainless steel (SS 316L) counterface in lubricated conditions. This work also provides a performance comparative assessment of HUmGO with respect to medical grades, UHMWPE (UC) and crosslinked UHMWPE (XL-UC). Significant attempts have been made to correlate the tribological properties (frictional behavior, wear rate, wear debris shape and size, wear mechanism) with the physicomechanical conditions (contact stresses) at sliding contact and the variation in molecular architecture of different UHMWPE materials. Additionally, an emphasis is put forward to critically anlyze the nature of lubrication regime based on the bearing characterstic parameters. HUmGO exhibited a lower COF (0.07) and specific wear rate (2.86 × 10-8mm3/Nm) than UC and XL-UC under identical sliding conditions. The worn surfaces on HUmGO revealed the signatures of less abrasive wear and limited deformation. Based on the estimated lambda (λ) ratio and Sommerfield number, all the investigated sliding contacts exhibited boundary lubrication. Taken together, the modified GO reinforced HDPE/UHMWPE bionanocomposite can be considered as a new generation biomaterial for the fabrication of acetabular liner for hip-joint prosthesis.

Effect of roughness on the running-in behavior and tribofilm formation of carbon fiber reinforced PTFE composite in trace moisture environment

Counterface roughness is known to affect the tribological behavior of carbon fiber reinforced PTFE. However, the effect of roughness in trace moisture environments has not yet been extensively investigated. In this study, the tribological behavior and tribofilm formation were evaluated for a carbon fiber reinforced PTFE composite sliding in a trace moisture environment against 34CrNiMo6 steel counterfaces with different roughness. Tribotests were conducted with a three-pin-on-disc tribometer at a sliding velocity of 2.2 m/s and in a nitrogen environment with moisture content controlled to 11 ppm. Generally, smoother counterfaces gave lower wear, both during running-in and steady-state. Contrarily, the coefficient of friction was only affected by roughness during running-in. Surface analysis from different stages of running-in were done to elucidate the formation of tribofilms and their different characteristics. For the rough countersurface, a loosely adhered transfer film is transitionally formed at the beginning of sliding to enable the formation of a persistent transfer film. Contrarily, for the case of a smooth countersurface, the formation of a persistent transfer film is initiated from the start. Similarly for the rough and smooth countersurface, a micrometer thick tribofilm with excellent low friction properties is observed on the PTFE composite after running-in.

Dry Sliding Behavior and Particulate Emissions of a SiC-graphite Composite Friction Material Paired with HVOF-Coated Counterface

Dry sliding wear tests and corresponding particulate matter (PM) analysis were conducted on a newly developed SiC-graphite-based composite friction material, paired with two types of HVOF counterface/discs: WC-CoCr and WC-FeCrAlY coatings, with a conventional martensitic stainless steel counterface as a reference. The trials were conducted on a pin-on-disc testing equipment at room temperature and a constant sliding velocity and contact pressure of 7 m/s and 0.5 MPa, respectively. The coefficient of friction (CoF) curves with the uncoated disc exhibited considerable fluctuations. On the other hand, the coated discs featured an increase in the CoF at the beginning of the tests, followed by either a continuous reduction until the end of the testing duration or the attainment of a steady state regime. The pin wear and emissions with both coatings were appreciably lower when compared to the trials with the uncoated disc. The evaluation of the friction layer observed a significant contribution of the counterface for all the pairings. The PM analysis was conducted on the particles that were lying in the range of 10 μm and 2.5 μm on a scanning electron microscope (SEM), and particles from 2.5 μm and 1 μm on transmission electron microscope (TEM), with an emphasis on the particles that were detached from the pin surface and friction layer to explain the wear mechanisms for each pairing. Through this, the need for the proper selection of both friction material and counterface to avoid the emission of harmful compounds in the environment was highlighted.

An investigation into the tribological behaviour of cutting fluid additives on Ti‐6Al‐4V alloy

AbstractThe performance of polymer‐based and phosphorus‐based cutting fluid additives have been shown to depend on the machining conditions employed. This study investigated the tribological behaviour behind the previously reported machining performance of polymer‐based and phosphorus‐based additives on Ti‐6Al‐4V using ball‐on‐disc tests. The coefficient of friction (COF) was evaluated using ball‐on‐disc tests, surface characterisation was performed on the Ti‐6Al‐4V and steel ball counterfaces to investigate the wear and friction reduction mechanisms. The tribological performance of the phosphorus‐based additive was observed to be influenced by the applied load and temperature. The activation of this additive resulted in a reduction in COF at elevated temperatures. However, the activation temperature was observed to be influenced by the applied load. The COF associated with the polymer‐based additive was noted to increase as the temperature increased, regardless of the applied load. The formation of tribolayers from the additives was related to the COF behaviour as well as the surface damage on Ti‐6Al‐4V and lower material transfer to the steel counterfaces.

INFLUENCE OF TFE EXPLOITATION TEST CONDITIONS ON FRICTION AND WEAR OF POLYMER COMPOSITES

The creation of new composite self-lubricating polymer materials with the use of Armenian minerals, and the study of the filler influence on tribological processes and working parameters of tribojoints is an actual problem in machine and device building.The developed composites are characterized by increased wear resistance, improved strength characteristics, and a reduced coefficient of friction, which expands the range of possibilities of their application in modern friction units of machines.The processes of friction and wear of antifriction self-lubricating polymer materials are significantly determined by the phenomenon of friction transfer, which is an important aspect of the adhesion mechanism of polymer wear and plays a significant role in the mechanism of self-lubrication of metalpolymer friction pairs. The analysis of tribological tests of composite materials depending on test conditions is carried out. The tribological behavior of polyphenilene sulfide filled with molybdenum concentrate and polytetrafluoroethilene sliding against a steel counterface is investigated. The influence of the filler proportions, sliding speed and counterface roughness on the wear rate and coefficient of friction of the self-lubricating polymer-based composites has been studied. For this purpose pin-on-disk configuration and the design of experimental approach utilizing Taguchi’s orthogonal arrays are used, allowing to make a reasonable choice of composites with minimum wear.

Polyethylene glycol derived carbon quantum dots nanofluids: An excellent lubricant for diamond-like carbon film/bearing steel contact

Polyethylene glycol derived carbon quantum dots nanofluids were synthesized via a slow thermal oxidation process. The size of carbon quantum dots was ca. 2 nm and had a decreasing trend with the increase of oxidation time. When used as lubricant in a diamond-like carbon film/bearing steel interface, the nanofluids achieved an ultra-low friction coefficient (μ ≈ 0.02), much lower than that of original polyethylene glycol (μ = 0.12). The worn surface analyses revealed that the nanofluids could effectively inhibit the tribo-oxidation of steel counterpart that occurred under original polyethylene glycol lubrication, and hence reduced the abrasion component of friction. Especially, the poly-hydroxyl carbon dots and oxidized polyethylene glycol species in nanofluids induced a hydroxyl-rich sliding interface via their tribochemical reactions with friction surfaces, which promoted the adsorption of polyethylene glycol molecules on sliding surfaces. Along with the mild corrosion wear of steel counterface, this shifted the boundary lubrication to a mixed/film lubrication regime, thereby achieving an ultra-low friction coefficient. The above results suggest that the polyethylene glycol derived carbon quantum dots nanofluids should be a quite excellent candidate lubricant for solid-liquid synergy lubrication based on diamond-like carbon films.

TO ESTIMATE AND PREDICT TRIBOTECHNICAL PARAMETERS OF FRICTION PAIRS FROM SINTERED POWDER FRICTION MATERIAL WITH DIFFERENT STEEL COUNTERFACES FOR DISK FRICTION DEVICE

Approximating dependencies of tribotechnical parameters of friction pairs sintered powder friction material and different steel counterfaces of disk friction device on sliding speeds, obtained by results of tests on friction machine and intended for selection of materials of friction pairs, are given.

An Evaluation of the Tribological Behavior of Cutting Fluid Additives on Aluminum-Manganese Alloys

The introduction of additives enhances the friction and wear reduction properties of cutting fluids (CFs) as well as aids in improving the surface quality of the machined parts. This study examines the tribological behavior of polymer-based and phosphorus-based additives introduced into cutting fluids for the machining of Al-Mn alloys. Ball-on-disc tests were used to evaluate the coefficient of friction (COF) and lubrication failure temperature to study the performance of the additives in the cutting fluids. Surface characterization was performed on the sliding tracks induced on the Al-Mn disc surfaces and used to propose the wear and friction reduction mechanisms. The polymer-based additive possessed a higher temperature at which lubrication failure occurred, displayed comparable COF at a lower temperature under certain conditions, and possessed a steadier tribological behavior. However, the phosphorus-based additive was observed to display lower COF and wear damage from 200 °C till failure. The lower COF values for the phosphorus-based additive at 200 °C corresponded with lower surface damage on the Al-Mn surface. The phosphorus-based additive’s performance at 200 °C could be attributed to the forming of a phosphorus-rich boundary layer within the sliding wear track, resulting in less surface damage on the Al-Mn surface and lower material transfer to the counterface steel ball surface.

Mechanochemical functionality of graphene additives in ultralow wear polytetrafluoroethylene composites

Poly-tetrafluoroethylene (PTFE) is a well-known solid lubricant, but its poor wear resistance limits its tribological applications. Certain carbonaceous fillers reduce PTFE wear rate by up to 4000-fold with no sacrifice of the friction coefficient; whereas the responsible mechanisms remain unclear. We systematically studied the effects of three graphene fillers with different aggregate strengths (graphene nanoplates, few-layer graphene and single-layer graphene) on the wear resistance of graphene-PTFE composites. The results found (1) graphene of weak aggregate strength outperform that of strong aggregate strength by 100 times in wear reduction, (2) strong correlations between wear rate, tribofilm carboxylate signal intensity and filler-matrix area per unit composite mass. The carboxylate signals likely correspond to chemical bonding between mechanochemically degraded PTFE, graphene and the steel counterface within highly crosslinked and adherent transfer films and worn polymer surfaces. Results in this study support two independent (primary versus secondary) wear reduction hypotheses in literature which were further backed by DFT simulations of filler-matrix interactions, TEM/EDS analysis of wear debris, SEM/EDS images of the polymer surfaces, and environmental test results in a dry argon (Ar) atmosphere. The results of this paper are also of instructive value for the development of solid lubricants with highly controllable wear characteristics.

Sliding Wear Characteristics of Carbon Filled Polytetrafluoroethylene (PTFE) Composite against AISI 304 Stainless Steel Counterface

In the present work, dry sliding wear characteristics of polytetrafluoroethylene (PTFE) composite reinforced with 35% by weight carbon fiber against AISI 304 stainless steel counterface is investigated with a view to consider PTFE composite as an alternative material for automotive applications. Dry sliding experiments were performed on pin-on-disk wear testing machine varying the normal load on pin, disk rotation (rpm) and temperature correlating with the range of pressure, sliding velocity and temperature variation at reciprocating conditions of compressor. A mathematical model to predict specific wear rate in terms of pressure and temperature was developed to understand parametric effect on wear rate. Specific wear rate has been observed to decrease with increase in pressure and temperature. Although, pressure (normal load) has been observed as more significant in lowering specific wear rate than temperature, no significant benefit was observed at higher ranges of pressure. Decrease in specific wear rate with increase in normal load (pressure) can be attributed to formation of transfer film at sliding interfaces. However, it is necessary to characterize transition of formation of transfer film varying with normal load and temperature respectively.

Influence of Bronze Filler upon The Friction and Wear of Polytetrafluoroethylene and Polyoxymethylene.(Dept.M)

The present paper deals with an experimental investigation carried out to elucidate the role played by polymeric and metallic fillers upon the coefficient of friction and wear rate of Polyoxymethylene (POM) and Polytetrafluoroethylene (PTFE).Lead bronze powder and PTFE powder were added by different percentages of volume to the base material to form a Composite. The study was performed on a pin-on-disk machine under constant load of 50 N and constant sliding speed of 1.0 m/s under dry sliding conditions. The results indicate that the addition of bronze or PTFE fillers always reduces the coefficients of friction and wear rates of tested materials and that reduction increases with the increase of filler content up to about 40%. The minimum valves of friction and wear were experienced by POM containing 36% PTFE. The paper attributes the reduction in friction and wear to the formation of polymeric transfer film adhering to the steel counterface which facilitates sliding and decreases adhesion.

Wear mechanisms of a sintered tribofilm in boundary lubrication regime

A research effort was conducted to investigate wear mechanisms of a sintered tribofilm formed by a zirconia nanoparticle antiwear additive. Spherical five nanometer diameter zirconium oxide (ZrO2) nanoparticles were dispersed in polyalphaolefin (PAO) synthetic base oil and used to generate approximately 120 nm thick tribofilms on AISI 52100 steel counterfaces in a ball-on-disk tribometer under boundary lubrication conditions. The sintered tribofilms were subsequently worn using the same conditions without the nanoparticle additive. Semi-in situ measurements of tribofilm thickness were conducted with an optical interference-measuring device to observe tribofilm growth and subsequent tribofilm wear. A rapid initial wear process was observed, however, a thinner tribofilm provided enduring protection of the substrate steel for the 120 min test duration. Without nanoparticles to replenish the tribofilm, the wear was deconvoluted from growth. Comparatively, lack of a tribofilm would result in scuffing within 10 min when testing the unadditized PAO base oil. Scanning electron microscopy and profilometry suggest the tribofilms were smoothened by the wear process. Evidence of crack formation between pores of the tribofilm illustrate a wear mechanism for the tribofilms. The cracks were concentrated where the contact pressure was the largest. Mild abrasive wear appeared as minor furrows in the sliding direction throughout the full width of the tribofilm.

Boride-Carbon Hybrid Technology for Ultra-Wear and Corrosive Conditions

This work discusses a study on a surface treatment for creating extremely durable low-friction, wear and corrosion-resistant surfaces for tribological components in harsh conditions. A duplex surface treatment was developed that combines the advantages of ultra-fast electrochemical boriding with those of hard tetrahedral amorphous carbon coatings. The friction and wear properties of the duplex treatment are compared to the boride-only treatment of AISI 1045 steel, while corrosion and contact fatigue behaviors of the duplex layer are compared to that of the single-layer carbon coating on low carbon steel. The duplex treatment yields wear rates as low as 6 × 10−8 mm3·N−1·m−1 and a coefficient of friction of 0.14 when tested against a steel counter face. The contact fatigue impact tests reveal that the high hardness of 1200 HV0.05 of the borided layer in the duplex treatment leads to higher resistance against indentation but is accompanied by a higher incidence of crack initiation, being in good agreement with the finite-element modeling of nanoindentation results. The duplex coatings exhibit resistance to pinhole corrosion as evidenced by a 3 h exposure to 15% HCl at room temperature.

The mechanisms behind the tribological behaviour of polymer matrix composites reinforced with TiO2 nanoparticles

In this present work, the sliding wear behaviour of hybrid polymer nanocomposites was investigated under different loading conditions and against different counterface roughness. Two different polymers matrices, epoxy and polyamide 66, with classic micro-sized short carbon fiber and graphite flakes as tribo-fillers were investigated with and without TiO2 reinforcing nanoparticles. It was found that the synergistic effect between nanoparticles and micro-sized fillers on friction and wear performance depended on the tribological system involved. In particular, for epoxy-based composites, the incorporation of TiO2 nanoparticles was only beneficial against a sufficiently rough disc but detrimental otherwise. Whilst for polyamide nanocomposites, the combination of nanoparticles and other fillers resulted in low friction and wear against both rough and smooth disks, particularly at higher applied contact pressures. When the cross-sections of the transfer films were analysed using a high-resolution SEM, it was found that TiO2 nanoparticles are only beneficial if they can blend with other wear debris to form a TiO2-enriched transfer film. The strengthened film provides the support required for other dislodged TiO2 nanoparticles to achieve the rolling effect, thus reducing friction and wear. In contrast, if TiO2 cannot effectively blend into the transfer film, TiO2 nanoparticles act as an abrasive that readily abrades away the comparatively softer film, thus exposing the polymer to fresh asperities on the steel counterface, a detrimental outcome to both friction and wear. Hence, to design high wear resistant composite materials, it is important to understanding the interactions between different tribo-fillers for particular circumstances or contact conditions.

Influence of Alkali Treatment and Maleated Polypropylene (MAPP) Compatibilizer on the Dry‐Sliding Wear and Frictional Behavior of Borassus Fruit Fine Fiber (BFF)/Polypropylene (PP) Polymer Composites for Various Engineering Applications

Tribological properties of the novel Borassus fruit fine fiber‐ (BFF‐) reinforced polypropylene (PP) composites with respect to fiber matrix surface modifications have been described. Composites were fabricated by an injection molding process using Borassus fruit fine fiber (BFF) of 5 wt.% as reinforcement and polypropylene (PP) as a matrix component. Fibers were treated with alkali (T) to remove the residual lignin (if present) and to enhance the interfacial adhesion between the fiber/matrix interface. Alkali treatment reveals additional reactive functional groups here on the surface of the Borassus fiber, allowing effective interaction bonding with the polypropylene matrix. Borassus fibers are primarily treated with an alkali solution to extract weaker unstructured amorphous constituents so that the fibers retain crystallized components, thereby strengthening the fiber’s strength. A 5 wt.% of maleated polypropylene (MAPP) was used as a compatibilizer to improve the interfacial adhesion between fiber and the polymer matrix. The wear and frictional behavior of BFF/PP composites with respect to the modifications were evaluated by steel counterface utilizing pin‐on‐disc test contraption under dry‐sliding conditions. The sliding velocity, applied load, and sliding distance were maintained as 2.198 m/s, 9.81–29.43 N, and 4000 m, respectively. The results demonstrate that the reinforcement of BFF to polypropylene matrix and the modifications improved the wear properties of the neat polymer matrix. Findings concluded that the abrasive wear resistance of T + PP + MAPP composite showed better interfacial adhesion and bonding, thus resulting in better tribological performance as compared to the other three compositions under different loading conditions. The effective substantial improvement of the coefficient of friction has been observed in alkali‐treated fiber and polypropylene matrix with MAPP compatibilizer (T + PP + MAPP) composites due to the presence of MAPP compatibilizer and alkali‐treated fibers. The frictional coefficient of T + PP + MAPP possesses better interfacial bonding strength upon NaOH treatment, and coupling agent, which results in enhancement of effective contact surface area and good surface friction characteristics, has been observed under different loading conditions. The fracture mechanism of worn‐out portions of BFF/PP composites was studied using high‐resolution scanning electron microscopy to analyze various imperfections like debonding, splits, fiber cracks, and wreckage or fragments formation.

The Structure and Properties of 65 wt.% Fe–35 wt.% FKh800 Chromium Carbide Steel Doped with Titanium Boride Additions

The effect of TiB2 additions on the structure, phase composition, and mechanical and tribological properties of materials in the Fe–FKh800 system was studied. The introduction of titanium boride additions activated compaction of the iron-based composites through sintering with participation of the liquid phase that emerged with the formation of low-melting Fe–C–B (Tm ~ 1050°C) and γ-Fe–Fe2B–TiB2 (Tm ~ 1162) eutectics and led to a 50–70°C decrease in the sintering temperature of the compacts. Titanium boride additions between 0.38 to 0.74 wt.% provided 20–25% higher bending strength of the 65 wt.% Fe–35 wt.% FKh800 composite with a slight increase in hardness. Metallographic studies, X-ray diffraction, and electron microprobe analysis of the Fe–35 wt.% FKh800–TiB2 materials showed that titanium boride additions promoted a multiphase, microheterogeneous matrix-reinforced composite, consisting of Kh17 chromium steel, double M7C3 and M3C iron–chromium carbides, and complex Me3(CB) carboborides. The influence of TiB2 additions on the wear resistance of the composites subjected to dry friction against fixed diamond wheel particles and ShKh15 steel was studied. The study showed that the abrasive mass wear (Im) of carbide steels decreased from 36.94 to 14.8 mg/km and their linear wear (Il) decreased from 0.197 to 0.079 mm/km with TiB2 additions increasing from 0.38 to 1.48 wt.%. Titanium boride additions ranging from 0.38 to 2.2 wt.% reduced the mass wear rate from 4.9 to 1.9 mg/km in dry friction of the composite against a ShKh15 steel counterface with 50–55 HRC hardness and decreased the friction coefficient from 0.49 to 0.38.

Friction and wear of additive manufactured polymers in dry contact

• The friction and wear mechanism of additively manufactured Polyjet parts are investigated. • The tribological dependence on applied load at 1N, 5N and 10N is studied. • The highest coefficient of friction is observed under 1N load for both parallel and perpendicular orientations. • Wear rate in Polyjet parts is influenced by the surface orientation to the sliding direction and applied load. The use of additive manufacturing (AM) is widely advancing the scope of rapid prototyping and manufacturing in tribological applications and material science research. However, there is still limited research focused on investigating the frictional and wear performance of AM polymers, especially of Polyjet manufactured parts. This work focuses on the effect of varying the contact load on the friction and wear mechanisms of additively manufactured acrylonitrile butadiene styrene (3D ABS) and Verogray polymers fabricated using Polyjet technology. Loads of 1, 5 and 10 N were applied under dry sliding contact with a 52100 steel counterface at room temperature. Dependence of friction and wear on the surface orientation to the sliding direction is noted. The results demonstrate that at 1 N load, the friction coefficient is primarily dependent on the orientation of the surface to the sliding direction. However, at higher loads of 5 N and 10 N, this dependency is shown to be a function of the bulk material properties rather than the surface roughness. Further correlation between the surface morphology and wear rate is shown to be dependent on the bulk material properties and the applied load. The results from this study provide alternate application uses for Polyjet materials in metal-polymer tribo-contacts for improved friction and wear performance.

Tribological characteristics of graphite epoxy composites using adhesive wear experiments

In this work, the characteristics of graphite/epoxy composites are estimated from a tribological perspective. Various weight percentages (0−7%) of graphite were used for adhesive wear experiments. The specific wear rate, friction coefficient, interface temperature and surface morphology of the composites were specified. Then the results were processed to obtain the optimum ratio in mixing the graphite with the epoxy. The main outcome of this work is to have established the significant effect of the fraction of weight of the graphite on the tribological achievement of the composites. Some intermediate weight percentage of the graphite in the epoxy composites is considered optimal for tribological achievement, since it significantly develops the resilience to wear and the frictional characteristics. Contrariwise, a higher amount of graphite in the composites (≥5%) has significantly negative effects on the tribological properties of the composites. Increasing the graphite content in the epoxy matrix has a positive effect on the interface temperature: the interface temperature went down as the graphite content rose. It was also clear that the higher the friction the higher the interface temperature. Regarding the surface roughness, the optimum graphite content in the epoxy composite was 3% in order to maintain low roughness surfaces for both the epoxy composites and the wear track of the stainless steel counterface.