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In this article, the authors present the results obtained within a complex experimental program that focuses on determining the tribological characteristics of the friction materials used in transmission belts, which are critical active components in manipulators within the pharmaceutical industry. The elements of transmission belts, having the role of ensuring the movement of cardboard packaging—used when packing the foils with medicine capsules—and stopping them during the insertion of the foils, were studied. This repetitive cycle—travel-braking—leads to the wearing of the friction material on the active surface of the belt. The experiments were carried out in a dry environment (air) by testing different types of friction materials (original belt, 3D printed TPU 60A, and TPU 95A). While the study is limited to these three materials, the results highlight the significant influence of material type and infill percentage on the coefficient of friction (COF) and wear resistance. TPU 60A achieved the highest COF at 100% infill, indicating a superior grip but experienced substantial wear, under the same conditions. Conversely, TPU 95A demonstrated a lower COF, suggesting reduced grip, but exhibited exceptional wear resistance. The aim of the research is to provide a preliminary investigation into the materials' wear resistance and braking effectiveness. The experiments utilized appropriate samples to replicate real operational conditions, particularly focusing on the nature of contact between the moving belt and the packaging. [ABSTRACT FROM AUTHOR] more...

There has been growing interest in using sustainable and eco‐friendly products to produce engineering materials. For this purpose, composite material applications obtained from agricultural wastes are gaining popularity. This study examines the synergistic effect of rice husk and rice stalk wastes on the fade and recovery performance of brake friction composites. Brake friction materials were developed using rice husk and rice stalk separately and in two different weight percentages as a 5–10 ratio in the formulation. For comparison purposes, a reference brake pad using copper as a substitute and a commercially available brake pad were used. Various physical, mechanical and thermal properties were analyzed. The tribological behavior of friction composites was evaluated on the Krauss test device in line with the ECE R90 procedure. The worn surface properties were analyzed using scanning electron microscopy. Tribo test results of friction composites were taken as criteria for performance optimization. While the importance weight of the criteria was determined by AHP, the VIKOR method was used in the sorting of alternatives. The experimental results have revealed that rice husk‐added friction composites had a good coefficient of friction value with better fade and recovery performance compared to rice stalk‐added ones. Increasing the amount of rice husk and rice stalk in the formulation tended to decrease the fade performance; however, it has increased the wear rate and recovery properties. Optimization results have shown that the brake friction composite containing 5 wt % rice husk ranks first in meeting the desired tribological criteria. Highlights: Cu‐free rice husk and rice stalk‐added friction composites were developed.Fibrous structure in the matrix developed the contact plateaus.Rice husk‐based tribo‐layer protected the composite from further wear damage.The addition of agro‐waste to friction composites exhibited good potential. [ABSTRACT FROM AUTHOR] more...

Highlights To investigate the influence of waste tire rubber (WTR) and fly ash (FA) on mechanical and tribological properties of composite brake linings, 8 different formulations of 8–40 wt% FA and 10–12 wt% WTR were selected. The mechanical tests showed that high amounts of resin and FA result in the highest hardness. The inclusion of WTR, decreased hardness and internal shear strength; however, increased the acetone extraction and resistance to coefficient of friction (COF) fluctuations. With the use of WTR, steady COF fluctuations with the temperature changes are achieved. The tribological properties were evaluated with both a drum‐type and disc‐type dynamometer by the SAE‐J661 standard. Reduced COF fluctuations were observed in <15 wt% FA and 10 wt% WTR containing samples. The highest COF was obtained for the 14 wt% FA and the lowest wear rate for the samples containing 8 wt% FA. The brake composites exhibited consistent COF in the range of 0.34–0.52, and wear rates lower than 7 wt%. Two compositions containing 40 and 25 wt% FA (no WTR), and one containing 10 wt% WTR and 8 wt% FA provided the best results. Finally, four best compositions were selected and worn surfaces were analyzed with SEM after full‐scale dynamometer tests. Three composites with high waste percentage were successfully manufactured Fly ash and waste rubber are used without any post‐processing to cut costs Waste rubber increased resistance to COF fluctuations with temperature change Full‐scale dynamometer tests are performed for friction and wear properties Worn surfaces were analyzed with SEM method [ABSTRACT FROM AUTHOR] more...

An innovative prototype composition of a composite friction material was developed. The actual values of selected parameters were determined, as described in a previous paper. It was decided to verify whether the proposed material differs from conventional materials in terms of temperature characteristics, and if so, to what extent. For this purpose, numerical studies were performed using the problem of initially boundary thermal conductivity. The braking system of a popular passenger car was used as the object of the research. A mathematical model of the studied phenomenon was developed, which was implemented in a virtual environment. The results showed that changing the reinforcement method to a more ecological one than the conventional one does not cause significant changes in the temperature profiles obtained for the adopted braking scenario. [ABSTRACT FROM AUTHOR] more...

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

Wear caused by friction is one of the main causes of most mechanical component failures. The application of powders as anti-wear lubricating materials has achieved great advances, which are of great significance in reducing friction and wear. This review focuses on the applications of phyllosilicates mineral powders as anti-wear lubricating materials in lubricating oil. The tribological behaviors of phyllosilicates mineral powders and the combination of phyllosilicates mineral powders with other materials as lubricant additives are provided. Moreover, the fundamental mechanism are systematically reviewed and concluded based on tribology data and surface, and interface analysis. Finally, current unsolved issues and suggestions for future research on phyllosilicates mineral powders as lubricant additives are proposed. [ABSTRACT FROM AUTHOR] more...

Braking systems are extremely important in any vehicle. They convert the kinetic energy of motion into thermal energy that is dissipated into the atmosphere. Different vehicle groups have different nominal and maximum speeds and masses, so the amount of thermal energy that needs to be absorbed by the friction pads and then dissipated can vary significantly. Conventional friction materials are composite materials capable of withstanding high temperatures (in the order of 500–600 °C) and high mechanical loads resulting from braking intensity and vehicle weight. In small vehicles traveling at low speeds, where both the amount of thermal energy and its density are limited, the use of slightly weaker friction materials with better ecological properties can be considered. This work proposes a prototype composite friction material using flax fibers as reinforcement instead of the commonly used aramid. A number of samples were prepared and subjected to laboratory tests. The samples were prepared using components of plant origin, specifically flax fibers. This component acted as reinforcement in the composite friction material, replacing aramid commonly used for this purpose. The main tribological characteristics were determined, such as the values of the coefficients of friction and the coefficients of abrasive wear rate. For this purpose, an authorial method using ball-cratering contact was used. The results were analyzed using statistical methods. It was found that the composite material using flax fibers does not differ significantly in its tribological properties from conventional solutions; so, it can be assumed that it can be used in the vehicle's braking system. [ABSTRACT FROM AUTHOR] more...

The ball-on-disk friction and wear tests were conducted using the materials of carbon/silicon carbide (C/SiC) carbon-ceramic composite disk and SiC ball at air atmosphere with different temperatures, including room temperature, 400 °C, and 700 °C. Then, the coefficients and wear rates were obtained, and changes in microstructure and chemical element composition were examined before and after the wear tests. On this basis, the mechanisms of wear and weight loss at different temperatures were analyzed. The results indicated the tribological properties of the composite can be significantly affected by high-temperature oxidation reactions. The frictional coefficients under high temperature conditions of 400 °C and 700 °C are significantly larger than those at room temperature. However, due to the smooth oxidation product of the SiC matrix at temperatures exceeding 700 °C in worn area, the frictional coefficient at 700 °C is slightly smaller than 400 °C. The weight loss of C/SiC composite after high temperature wear test is attributed to the combined effects of oxidation and abrasion. Due to different material consumption mechanisms, although the C/SiC composite can obtain higher frictional coefficient under high temperature condition, the overall consumption of the composite at high temperature is larger than that at room temperature. [ABSTRACT FROM AUTHOR] more...

The tribological performance of C/C–SiC paired semi-metallic brake pads suitable for automobiles was investigated in this study. Factors on tribological properties of semi-metallic brake pads such as the contents of phenolic resin, copper fibers, steel fibers and MoS 2 were tested by the orthogonal experimental. According to the SAE-J2522 test procedure, an optimized compositional formulation was derived based on the brake test results combined with fuzzy comprehensive evaluation. The wear mechanism of brake pairs was discussed, and the compositional formulation of the brake pad was further optimized after the analysis of the friction surface morphology before and after braking. The results showed that copper fibers had the greatest effect on the friction performance of brake pads. Copper fibers contributed to stabilization of the coefficient of friction (COF) and effectively improved the wear resistance. However, at higher braking speeds (≥120 km/h), the copper fibers were converted from fibrous to flaky and softened, acting as a solid lubricant on the friction surface, resulting in a low COF of brake pads. The tribological performance of brake pads could be improved by reducing the content of copper fiber and increasing the content of hard particles. [ABSTRACT FROM AUTHOR] more...

In this study, a fixed automotive friction material content was determined and the mechanical and tribological effects of manufacturing parameters on friction materials were investigated. Parameters; pre-form- ing time (1-3-5 min) and pre-forming pressure (8-10-12 MPa), hot pressing time (5-10-15 min) hot pressing pressure (8-10-12 MPa) and hot pressing temperature (125-150-175 °C), curing time (4-8-12 h) and curing temperature (120-150-180 °C) were determined. The friction test of the produced samples was carried out under 0.551 MPa pressure and 7 m/s rotation speed for 90 min. In addition, the average COF, friction stability, specific wear rate, density and hardness values of the samples were calculated. According to the results obtained, the average COF value increased as the pre-forming time and pressure increased. The lowest specific wear rate among all specimens was calculated as 7.622 x 10-6 cm³/Nm in PFP-12 spec¬imen. With the increase in hot pressing time, the tribological properties of friction materials improved. The highest friction stability among all samples was calculated as 79.42% in the HPT-15 sample. Although there was an increase in the average COF value with increasing hot pressing pressure and temperature, the specific wear rates increased in these parameters. The highest average COF value among all samples was obtained in the CT-12 sample with a value of 0.553. The specific wear rate increased with the increase in curing time and temperature. The highest specific wear rate among all samples was calculated 10,743x10-6 cm³/Nm in the CTe-180 sample. Finally, it has been suggested that 3 min for pre-forming time, 12 MPa for pre-forming pressure; 15 min for hot pressing time, 12 MPa for hot pressing pressure, and 150°C for hot pressing temperature; and a curing time of 8 h and curing temperature of 150 °C may be sufficient. [ABSTRACT FROM AUTHOR] more...

Superlubricity, the tribological regime where the coefficient of friction between two sliding surfaces almost vanishes, is currently being investigated as a viable route towards the energy efficiency envisioned by major long-term strategies for a sustainable future. This current study provides new insights towards the development of self-lubricating systems by material and topological design, systems which tend to exhibit near-superlubric tribological performance, by reporting the synergistic effect of selective surface patterning and presence of carbon micro/nano-fillers on the frictional coefficients of additively manufactured structures. Geometric and biomimetic surface patterns were prepared by fused deposition modelling (FDM), using printing filaments of a polymeric matrix infused with graphene nanoplatelets (GNPs) and carbon fibers (Cf). The calorimetric, spectroscopic, mechanical and optical microscopy characterization of the starting materials and as-printed structures provided fundamental insights for their tribological characterization under a ball-on-disk configuration. In geometrically patterned PLA-based structures, a graphene presence reduced the friction coefficient by ca. 8%, whereas PETG exhibited the lowest coefficients, in the vicinity of 0.1, indicating a high supelubric potential. Biomimetic patterns exhibited an inferior frictional response due to their topologically and tribologically anisotropy of the surfaces. Overall, a graphene presence in the starting materials demonstrated great potential for friction reduction, while PETG showed a tribological performance not only superior to PLA, but also compatible with superlubric performance. Methodological and technical challenges are discussed in the text. [ABSTRACT FROM AUTHOR] more...

The composite materials are fabricated by combining various ingredients to make higher material properties as required by various industries. The primary classification of composites is based on their build ingredients, such as binder, fibre, reinforcement and fillers. The characteristics of individual ingredients influenced the properties of composites. Further, friction materials are those composite materials efficiently used in vehicles' braking. Researchers have tried the various formulations of friction materials because it is very significant to study the mechanism and material characteristics due to the safety measures of vehicles. The current study examines the various brake composite materials' characteristics and their mechanical and tribological performance in this article. The tribological study includes the various terminologies used in friction and wear using pin-on-disc, dynamometer, field studies, etc. The effects of numerous elements impacting the wear of frictional materials are given, and the tribological performances of used friction materials are given the utmost attention. [ABSTRACT FROM AUTHOR] more...

In this study, the potential of Fe3Al coating material as an environmentally friendly alternative to coatings containing critical elements for brake discs was investigated. A buffer layer of Cr–Mo steel (Ferro 55) that was about 500 µm thick was applied on a gray cast iron disc to enhance the coating quality and prevent the formation of hot cracks during solidification. The microstructural analysis of the cross-section of the coating showed that the buffer layer diffused into the Fe3Al coating, forming a combination of Fe3Al, Fe, and Fe3AlC0.5 phases. The tribological properties of the Fe3Al-coated disc were evaluated using pin-on-disc tests against two different copper-free friction materials extracted from commercial brake pads. The wear results show a coefficient of friction comparable to that of an uncoated disc (≈0.55), but with a reduction in particulate matter (PM) emissions, which decreased from 600 to 476 #/cm3. The last issue is an interesting aspect that is gaining increasing importance in view of the upcoming international standards. [ABSTRACT FROM AUTHOR] more...

Brake pads are vital parts of automobiles, where tribological properties are prime concern. Usually, asbestos brake pads were used, which were replaced by copper-based in later years. As brake lining materials have evolved, synthetic friction composites were explored as alternatives. Recent works suggest that, natural composites are promising friction material. However, poor thermal conductivity and frictional stability have limited their applications. Surface treatment of fibers and addition of secondary fillers have improved their possibilities. Thus, hybridization of reinforcements has expanded their range of applications. The present article attempts to review various aspects of brake pads and their testing with attention on natural composites. Their properties were studied to conform their ability to meet desired requirements. The article reviews the studies conducted in recent years on various materials properties related to brake pads. The future potential of natural components in the development of friction composite materials for automotive applications is highlighted. [ABSTRACT FROM AUTHOR] more...

The sintered brake pads have been the most commonly utilized brake pads in wind turbines, as it stalls the rotor after shutdown or in case of emergencies. It is a mixture of metallic particles that are pressed together. But it has been noticed that the friction at interface generates the spark in adverse conditions, which cause a fire in nacelle. Due to this a compact unit for fire suppression is used, which adds the additional cost in brake system. Therefore, it is necessary to address the spark issues coming from brake pads under adverse conditions through developing a brake pad using alternate route. Hence, a composite brake button was developed through a compression moulding route, that is, cost economic route. Despite the different compositions and manufacturing routes of materials, a similar frictional behaviour is observed after testing using friction test rig. Further, it is observed a marginally higher friction values for sintered pads. Moreover, the physical and mechanical properties like density, hardness, porosity, shear strength, compression strength, etc., are also found to be similar. In fact, the density of a composite pad is observed 34.7% lesser than sintered pad. Both the developed brake pads have a mean dynamic friction coefficient (∼0.4–0.5) with a mean static friction coefficient of approximately 0.45. In spite of more hardness, the wear resistance is found poorer in sintered pads as compared with composite pads. Hence, it can be concluded that the developed composite pad shows better tribomechanical performance and suitable for application without spark issues. [ABSTRACT FROM AUTHOR] more...

Polyether ether ketone (PEEK) is a widely used material for friction pairs due to its excellent mechanical strength, good wear resistance, and chemical inertness. However, some modifications are necessary when PEEK is used as a water-lubricated friction pair. In this study, a novel sulfonation method was developed to design a water-lubricated friction pair with ultralow friction, good wear resistance, and high loading capacity. PEEK powders were sulfonated using ClSO3H and sintered to form bulk plastic. The sulfonated PEEK (SPEEK) plastic exhibited good tribological properties. At a low sliding speed, the friction coefficient was smaller than 0.02 when a 3 wt% NaCl solution was used as the lubricant. The order of magnitude of the wear rate was as low as 10−8 mm3/(N·m). The mechanism of friction reduction was mainly hydration lubrication. The negatively charged −SO3− groups on the friction pair can adsorb hydrated Na+ cations by electrostatic interactions. These hydrated Na+ cations have a high load capacity and low shearing resistance. The ultralow wear mechanism observed in this study is possibly due to ultralow friction properties of the friction pairs prepared through the proposed sulfonation and thermoforming procedures. [ABSTRACT FROM AUTHOR] more...

The stability of the graphite seal device is a key factor for the normal operation of aero engines. However, conventional graphite exhibits poor comprehensive performance due to its porous structure, which limits its application at high temperatures. Therefore, in this paper, phosphate was used to impregnated graphite pores, and the interaction between the friction, wear, and oxidation of phosphate-impregnated graphite against superalloy at high temperatures was studied through pin-on-disk friction tests. The results revealed that the coefficient of friction (COF) of matrix graphite fluctuated greatly, from 0.07 to 0.17, in the range of 100 °C to 500 °C, while the COF of impregnated graphite was stable, at around 0.13, from 100 °C to 500 °C. The wear rates of the two types of graphite were close from 20 °C to 300 °C, while the wear rate of the impregnated graphite was significantly lower than that of the matrix graphite at higher temperatures, from 400 °C and 500 °C. The reason was that the impregnated phosphate reacted with graphite at a high temperature, forming the inert site which helped to inhibit the oxidation and maintain the mechanical properties of the impregnated graphite at high temperatures. In addition, the impregnated graphite could maintain better integrity of the contact surface and reduce the inclusion of large hard metal oxides, thus effectively reducing the abrasive wear of the disk. Therefore, the wear depth of the superalloy disk samples with impregnated graphite was significantly lower than that of the matrix graphite. The results promote the application of phosphate-impregnated graphite under the high temperature conditions of aero engines. [ABSTRACT FROM AUTHOR] more...

This study explains the design of a single-plate clutch using experimental measurements. The ratios of materials used to make the samples were 34g of Kevlar fiber (aramid 49 type), 150g of epoxy-type Sikadur-52, 10g of iron powder, and 10g of graphite powder. The three different sample types were made as laminates and cut using water cutter machinery according to the ASTM standard for each test. The following procedures were taken: The prepared mold was created first. Epoxy and the hardener were mixed in a 2:1 ratio. After that, the mixture was stirred well for a sufficient period of time. Then a quantity of the epoxy mixture was placed in the mold, and Kevlar fibers were placed in layers. The following ratios were used to create three samples: Sample 1 (34 g of Kevlar fiber, 150 g of epoxy), Sample 2 (34 g of Kevlar fiber, 150 g of epoxy, 10 g Fe), and Sample 3: Kevlar fiber (34 g), graphite (10 g), epoxy (150 g), and iron (10 g). The following facts have been found: When Kevlar fiber (aramid 49 type) was used at a weight of 34g for all samples, the best performance was achieved by hybrid composite sample3, which has the highest values (modulus of elasticity and higher wear resistance) in comparison to the other two composite samples (sample2 and sample1). In comparison to composite sample 1, the hybrid composite samples 2, and 3 have the highest value. (Tests for hardness). [ABSTRACT FROM AUTHOR] more...

Purpose: This study aims to compare the friction and wear performance of commercial brake pads for four wheelers among metallic, semimetallic and non-asbestos organic (NAO) formulations to identify one with the right combination of properties for optimal performance. Design/methodology/approach: Three commercially available brake pads for four-wheeler automotive applications were acquired. Samples were cut from the brake pads to study their physical and mechanical properties. The effects of friction and wear were analyzed using a pin-on-disk tribotester. Surface morphology on the worn-out surface of the brake pads was studied. Findings: It was observed that the frictional properties remained stable and less fluctuating in the semimetallic and NAO pads, whereas the coefficient of friction of all the pads varied between 0.35 and 0.55. The wear rate of the metallic pads is less than that of NAO and semimetallic pads. The surface morphology studies revealed that the metallic pads contained more primary plateaus and smaller amounts of secondary plateaus compared to semimetallic and NAO pads, resulting in better wear resistance characteristics. Originality/value: Because the market is flooded with various options for brake pad materials, it is imperative that the vehicle manufacturers choose the right pad material with great care not only to ensure the optimal functioning of the braking system but also passenger safety. Mechanical and tribological properties of brake pads contribute greatly to their effectiveness. There is a requirement to choose the proper material for a certain application that has a consistent friction coefficient and reduced wear. [ABSTRACT FROM AUTHOR] more...

Twin disc tests are performed to determine the wear behaviour of three advanced crossing materials. In particular, the austenitic Hadfield steel Mn13, the ultrafine-pearlitic R400HT and the chromium bainitic CrB1400 steels are benchmarked. The investigated crossing materials are combined with the standard wheel material ER7. The tests are performed under two different contact pressures, 1 400 and 1 800 MPa, respectively. Dry conditions and a slip of 0.5% are used. The parameters evaluated are: wear rates, wear debris, plastic deformation, microstructural changes, friction coefficient and material hardness. R400HT is identified as exhibiting the highest wear resistance, although CrB1400 shows comparable results. Mn13 exhibits the highest wear rates. Three primary reasons for the elevated wear rates of Mn13 are identified. These include a significantly lower initial hardness, a distinct hardening mechanism in conjunction with a high work-hardening potential and a different wear mechanism that shows a high dependence on the applied contact pressure. The different wear mechanism is expected to be the main driver for the high wear rates. • Wheel-rail contact. • Wear. • Twin disc tests. • Advanced crossing materials. • Hadfield steel. [ABSTRACT FROM AUTHOR] more...

This research explored high-performance epoxy resin (EPR) for the first time as a binder in the formulation of brake pads to overcome the limitations of phenolic resins (short shelf life, harmful emissions, etc.) and compared them to phenolic pads to determine their potential. EPRs offered higher heat resistance, lower density, post-curing free, and longer shelf life. Brake pads (15%, 20%, and 25% epoxy, and 20 vol% phenolic) were assessed for physical, mechanical, thermal, tribological, and noise - vibration (NV) properties. The findings revealed promising tribological and NV performance for epoxy pads, suggesting EPR has the potential to replace phenolic resins in the friction industry. • High-performance, eco-friendly epoxy resin replaced phenolic resin (PhR) in brake pads. • 15 vol% epoxy pads outperformed (tribological and NV) PhR-based pads. • Epoxy resin offers longer shelf life, reduces hazardous emissions, and eliminates the need for post-curing. • A challenge to replace PhR in the friction industry has been addressed successfully. [ABSTRACT FROM AUTHOR] more...

Two-dimensional (2D) layered materials such as transition metal dichalcogenides (e.g., MoS 2 , WS 2) and MXenes (e.g., Ti 3 C 2 T x), as well as hybrids of these materials are the focus of current research in solid lubrication due to their outstanding performance. Transition metal carbo-chalcogenides (TMCCs), consisting of an MXene core and a TMD-like surface, represent an inherent combination of TMDs and MXenes without the need to construct hybrids out of the individual layers. Due to their layered structure and surface chemistry, favorable tribological properties can be expected from these novel materials. Here, multilayer Ta 2 S 2 C and Nb 2 S 2 C TMCCs are deposited solely as a powder onto a steel substrate and their tribological properties under linear sliding against different counterbodies, i.e., Al 2 O 3 , SiC, 100Cr6, and polytetrafluoroethylene (PTFE) are discussed. Advanced materials characterization techniques are used to detect the presence of TMCCs inside the wear tracks and to reveal their 2D structure within the tribofilm. Finally, density functional theory (DFT) simulations are used to unravel the easy shearability of TMCCs at the nanoscale. The results demonstrate the great potential of this new 2D material family, which also offers many possibilities for defined tuning of the solid-solid interface. [Display omitted] [ABSTRACT FROM AUTHOR] more...

In this study, advanced aluminium metal matrix hybrid surface composites were synthesized using the five-pass friction stir processing (FSP) technique. A blend of Hybrid reinforcement particles, silicon carbide and cerium oxide, were incorporated into the Al-5052 matrix at varying SiC: CeO 2 ratios of 100:0, 75:25, 50:50, 25:75, and 0:100. The multi-pass FSP methodology ensured thorough mixing and uniform nanoparticle distribution, resulting in tailored microstructures. The optimal 75:25 SiC: CeO 2 ratio exhibited superior microstructural, anti-corrosion, and tribological properties, with the lowest wear rates of 8.3 × 10−9 and 8.8 × 10−9 mm3/m at 15 N and 25 N loads, respectively, and the lowest corrosion rate of 8.06 mm per year compared to other hybrid blends. [Display omitted] [ABSTRACT FROM AUTHOR] more...

Chemical mechanical polishing is a hybrid polishing technique having different applications in the semiconductor industry, biomedical and optical instrumentation, and defense equipment. The control and accuracy highly depend on the operator's skill due to limited knowledge of material removal behavior. This article attempts to fill this gap through an experimental investigation of friction coefficient and material removal rate as functions of abrasive particle size, normal load, relative velocity, and polishing time during BK7 optical glass polishing. In this article, Taguchi L18 mixed levels full factorial design was used to perform the experiments. Also, a temporal model for material removal rate is developed to study and investigate the mechanism of material removal. The results show the load per particle varies between 0.18 × 10–6 and 4.1 × 10–6 N, which led to the conclusion that material, are removed plastically from the workpiece surface and mechanical actions are dominant over chemical actions in material removal. The values of friction coefficient (μ ~ 0.1) and 3D profilometer images also support this statement. The errors between predicted and experimental results are well within 8% and 12% for friction coefficient and material removal rate, respectively. This study is an important step toward the deterministic optical polishing process, leading to better control of material removal during the polishing of precision optical components. [ABSTRACT FROM AUTHOR] more...

Copper-based functionally gradient composite material is developed using powder metallurgy processing technique, as a potential wind turbine brake pad material. The developed composite has a gradient composition of Cu, CeO2, Al2O3, Fe, and Cg to enable joint strength at the interface (brake calliper) and wear resistance at the contact surface (brake disc). The article presents a comprehensive analysis on the microstructure, microhardness, and tribological performance of the developed composite. The wear mechanism is deduced through surface morphology, elemental composition, and phase composition analysis using field emission scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffractometer, and X-ray photoelectron spectroscope. A maximum hardness of 198.2 HV was obtained at the contact surface. Experimental values from tribology tests show that a decreasing trend was obtained with a wear rate of 2.013 × 10−7 g N-m−1 and a friction coefficient was 0.215. [ABSTRACT FROM AUTHOR] more...

In this paper, an automobile brake lining made of wood ceramic is proposed, and a 3D model of a disc brake of a wood ceramic brake lining is established to simulate the thermoelastic coupling characteristics of the disc brake under the action of the wood ceramic brake lining under various braking conditions. Based on the Archard wear model and the UMESHMOTION subroutine in the ABAQUS software, the numerical simulation of the wear depth of the wood ceramic brake lining is realized. The results show that, when wood ceramic is used as the friction material of automobile braking, the peak temperature of the brake disc during the braking process is 254.25°C, which is 9.91°C lower than that of the traditional metal brake lining, and the stress distribution is uniform. It is beneficial to reduce the generation of thermal cracks in the brake disc, and at the same time reduce the influence of the " thermal decay " effect of the brake disc on the stability of the braking performance of the vehicle. The temperature of the wood ceramic brake lining can reach a maximum of 281.41°C during the braking process, which is far lower than the thermal decomposition temperature of the wood ceramic material, and has good reliability. With wood ceramic as the friction material of the brake lining, the maximum wear depth of a single high-speed emergency braking does not exceed 2.11 µm, which has good wear resistance. [ABSTRACT FROM AUTHOR] more...

The aim is to study the effect of several distinct manufacturing processes, parameters and ingredients on the physical, mechanical and frictional characteristics of brake pad developed using hand lay method (sample 1), brake pad developed using hot compression method (sample 2) and commercial brake pad (sample 3). The non asbestos brake pad samples were compared with the selected commercial brake pad sample using pin on disc test set up. Results showed that friction performances of all three samples were insensitive to water and oil absorption test. Sample 2 had better mechanical properties and greater wear resistance than other two samples which are attributed to use of hot press method of manufacturing the composite and selecting the carbonbased ingredients. Sample 1 maintained high coefficient of friction even though manufactured with the help of hand lay method. Both fabricated brake pads are stable upto the temperature 220 °C without any weight loss and degradation. Brake pad surfaces showed different shape wear debris and plateaus significantly affecting the friction characteristics. Finally, the test results indicated that both fabricated brake pad samples have potential braking characteristics to be used as a brake pad material. [ABSTRACT FROM AUTHOR] more...

Purpose: This study aims to determine the braking performance of limestone as a filler in brake friction materials. Design/methodology/approach: Samples containing limestone material (30-35-40%), which can be an alternative to brake friction material filler, were produced. The samples were weighed on precision scales, mixed homogeneously and produced using the hot molding method. The physical and tribological properties of the produced samples were determined, and their microscopic analyzes were made with scanning electron microscopy. Findings: As the amount of limestone increased, the density of the samples decreased. The friction coefficient and wear rates were close to each other and within the optimum limits for all samples. Limestone materials can be used instead of barite materials studied in the literature on brake linings. Microcracks were observed only in samples containing 30% and 35% limestone in microscopic images. Originality/value: In this study, the wear rate, coefficient of friction and microstructures on the friction surfaces of brake friction materials containing limestone were investigated. The usability of limestone as a filler in brake friction materials provides valuable information to researchers and industrial organizations in the brake friction material field. [ABSTRACT FROM AUTHOR] more...

In recent years, advancements on improving the mechanical and tribological properties of polyimide nanocomposites have remarkably increased, owing to the fact that polyimide nanocomposites exhibits lightweight, high strength, thermal stability as well as anti-wear and solvent resistance. The polyimide nanocomposites are described as material of polyimide matrix reinforced with certain volume or weight percent concentration of nanofillers. Researchers have demonstrated the importance of thermoplastic polyimide nanocomposites in mechanical, thermal, and tribological applications. However, the nanocomposites are reportedly facing interfacial adhesion issues and surface properties degradation, which have affected their mechanical, friction, and abrasive wear resistance for tribological applications. Although, much advancements on improving the mechanical, thermal, and wear resistance properties of polyimide nanocomposites has been reported. However, this review summarizes the effects of nanofillers, such as carbon nanotubes (CNTs), graphene (GN), graphene oxide (GO), boron nitride (BN), molybdenum disulfide (MoS2), silica (SiO2), titania (TiO2), alumina (Al2O3), carbon fibres (CF), aramid fibre (AF), glass fibre (GF), zinc dioxide (ZnO2), zirconium dioxide (ZrO2), silicon nitride (Si2N4), and carbon nitride (C3N4) on the mechanical, thermal, and wear properties of polyimide nanocomposites for tribological applications. The authors concluded the review study with advancement, challenges and suggestions for future improvement of polyimide nanocomposites as friction component material. Thus, the review offers an insight into the improvement and selection of polyimide nanocomposites material for mechanical, thermal, and tribological applications. More so, the review will also give away for further research. [ABSTRACT FROM AUTHOR] more...

AlSi7Mg/SiCp aluminium matrix composites (AMCs) with a high ceramic content (35 vol.%) that were produced by using the field-assisted sintering technique (FAST) were subjected to tribological preconditioning and evaluated as a potential lightweight material to substitute grey cast iron brake discs. However, since an uncontrolled running-in process of the AMC surface can lead to severe wear and thus to failure of the friction system, AMC surfaces cannot be used directly after finishing and have to be preconditioned. A defined generation of a tribologically conditioned surface (tribosurface) is necessary, as was the aim in this study. To simulate tribological conditions in automotive brake systems, the prepared AMC samples were tested in a pin-on-disc configuration against conventional brake lining material under dry sliding conditions. The influence of the surface topography generated by face turning using different indexable inserts and feeds or an additional plasma electrolytic treatment was investigated at varied test pressures and sliding distances. The results showed that the coefficient of friction remained nearly constant when the set pressure was reached, whereas the initial topography of the samples studied by SEM varied substantially. A novel approach based on analysing the material ratio determined by 3D surface measurement was developed in order to obtain quantitative findings for industrial application. [ABSTRACT FROM AUTHOR] more...

Brakes play an extremely important role in any vehicle. In today's automotive industry, friction brakes are most often used, in which the composite material of the brake pad cooperates with a cast iron disc. While little can be modified in the case of discs, in the case of pads, the composition of the material used for its production can have an almost unlimited number of possibilities. Both scientists and manufacturers invent and test new combinations to achieve the desired end result. A similar task was undertaken in this work. Bearing in mind the fact that materials commonly used as reinforcing materials generate undesirable threats in the production process, it was decided to check whether this role could be taken over by another substance that is already present in brake pads; this substance is copper. A number of samples containing copper, in the form of powder and fibers, were made, and then the samples were subjected to tribological tests in order to determine the coefficient of friction and abrasive wear rate. The ball-cratering research method was used, and the Taguchi process optimization method was used to plan the experiment. As a result of the tests, it was found that the replacement of aramid fibers with copper fibers does not significantly affect the value of COF and the abrasive wear rate. [ABSTRACT FROM AUTHOR] more...

The pin on the disc friction tester was used to conduct the intermittent braking testing of train brake materials with a low-temperature environment simulation device at temperatures 20 °C, 0 °C, −10 °C, −20 °C, and −30 °C. The results show that intermittent braking presents different wear characteristics of braking materials at low temperatures. Under different ambient temperature conditions, the most volatile friction coefficient caused by intermittent braking happens at 0 °C, and the wear rate of brake materials reaches its maximum at 0 °C. The wear surface morphology of the brake pad material mainly includes scratches, furrows, adhesions, and abscission pits, while the surface of the brake disc material was dominated by scratches, furrows, and adhesions. With the decrease in temperature, the adhesion damage of the brake pad/disc material increases. At 0 °C, the brake pad material has crack damage. [ABSTRACT FROM AUTHOR] more...

With recycling and reuse in mind, this study explores the possibility of the utilization of waste generated during the plasma cutting operations to produce aluminum products in a commercial friction material formulation for car braking applications. The as-received waste, analyzed in the form of a powder, was subjected to various characterization techniques to obtain its composition and phase constituents. The friction, wear, and emission analyses were organized in two ways: the first part focused on the selection of the most suitable waste content in the friction material formulation—10, 15, and 20 wt.%—tested in the form of pins, using a pin-on-disc tribometer. The second part evaluated the most suitable content in the formulation in the form of coupons on a subscale dynamometer to comprehend its friction and emission characteristics in a more complex scenario. Through the pin-on-disc analysis, it was seen that the 10 wt.% of waste in the formulation provided permissible friction and wear behavior, and similar emission magnitude and secondary plateau characteristics were seen, as compared to the reference composition. Similar results were recorded on the subscale dynamometer at mild braking conditions. At 'severe' testing conditions, a different trend was observed. Through this analysis, the possibility of the addition of this kind of waste in friction material composition has been evaluated deeply, paving a path for further analysis and possible implementation. [ABSTRACT FROM AUTHOR] more...

Aluminum matrix composites (AMC) were engineering materials that are widely used in the automotive industry and whose use is increasing day by day. This study investigated the wear behavior of ZrO2 and Graphite reinforced hybrid composites designed as an automotive friction material at different temperatures and their corrosion behavior in different. The powders prepared by adding 2% graphite and 12% ZrO2 to the Al powder were mechanically alloyed for 60 min. Wear tests were performed using three different loads, three different sliding distances, and five different temperatures. Corrosion tests were performed using electrochemical impedance and potentiodynamic polarization techniques at two different electrodes. Result of the study showed that the reinforcement material added to the matrix agglomerated at grain boundaries. Wear tests showed that weight loss increased with increasing load and temperature. Corrosion tests showed that the AMCs exhibited better corrosion resistance at the NaCl electrolyte than the H2SO4 electrolyte. Pitting corrosion was active at the NaCl electrolyte on the corrosion surfaces, while the fretting corrosion mechanism was active at the H2SO4 electrolyte. [ABSTRACT FROM AUTHOR] more...

Purpose: The purpose of this study was to investigate the use of boric acid as a friction modifier material in brake friction composites and to determine the effect of heat treatment applied during production on braking performance. Design/methodology/approach: The addition of five different amounts of boric acid was balanced with cashew, which is in the friction modifier material group. The samples were produced in the following order: dry mixing, preforming and hot-pressing. The effect of the heat treatment that can be applied after the hot-pressing process on the braking performance was investigated. The tribological and physical properties of the samples were determined using tests performed according to appropriate standards. The microstructures of the friction surfaces were investigated using scanning electron microscopy. Findings: It was observed that the tribological properties of brake friction composites containing 20% by weight of boric acid were improved. It has also been observed that the heat treatment applied after hot pressing increased the friction coefficient of the samples by 7% on average and decreased the specific wear ratio of the samples. When the surface morphologies of the samples are examined, it is seen that the friction layers of the heat-treated samples are wider, and the microvoids and cracks are reduced. Originality/value: This study showed that boric acid can be used as a friction modifier in brake friction composites. It also revealed the tribological and physical contribution of the applied heat treatment to the composite. Thus, it guides brake friction composite manufacturers in the industry and researchers working in this field. [ABSTRACT FROM AUTHOR] more...

The effect of the coke and flake graphite ratio (C/F ratio) on the microstructure formation and properties of Cu-based friction materials was investigated. The density, hardness, friction coefficient, braking properties of the Cu-based friction materials with different C/F ratios were tested. The microstructures, wear morphology, and frictional subsurface of the Cu-based friction materials were characterized by SEM. With the increase in coke content, the proportion of flake graphite with long strips shape decreased, and the coke with clump shape increased. The density of Cu-based friction material decreased continuously with the increase in the C/F ratio. The hardness of the Cu-based friction material decreased first and then increased gradually with the increase in the C/F ratio. With the increase in C/F ratio, the friction coefficient increased, and the wear loss decreased. Moreover, during the braking process, the surface temperature of the Cu-based friction materials first increased and then decreased, and the braking time decreased first and then increased with the increase in C/F ratio. The wear mechanism of the Cu-based friction materials was abrasive wear, fatigue wear, and oxidative wear. The failure of the Cr-Fe particles was oxidation, crushing, and wear. Relatively, the Cu-based friction material with C/F ratio of 7/2 had high friction coefficient, low wear loss, low surface temperature during braking, and low braking time, which indicated better combination braking properties. [ABSTRACT FROM AUTHOR] more...

Providing high-quality machinery and equipment in technical terms is an activity aimed primarily at ensuring the high reliability of nodes. Reliability of machinery and equipment is mainly characterized by resistance to destructive processes. Mutual displacement of parts causes destructive friction phenomena, the intensity of which can be intensified by the interaction of specific technological environments. The article presents the results of research on ring-on-ring samples made of C45 steel in the non-heat-treated state, which were subjected to mechanical, corrosive, and abrasive wear and various combinations of them. The main purpose of the study was to determine the wear that results from the action of destructive friction and corrosive processes with the presence of abrasive material in the tribological node. The results supplement the knowledge of material wear under the simultaneous action of several destructive factors. Based on the study, it was noticed that the sum component of mechanical–abrasive–corrosive interactions is about 40–50% of the total wear. Mass loss resulting from simultaneous mechanical and abrasive interactions is equal about one-third of the total wear. In addition, it was observed that the effects of the interactions of friction (mechanical), corrosive and abrasive excitations are synergistic in nature, which lead to increases in the total wear of the tested samples made of steel. The results of the research are of practical importance and allow for wear-optimal selection of material in the friction node of modern machinery and equipment. [ABSTRACT FROM AUTHOR] more...

In this work the effect of preliminary curing on mechanical, physicochemical and tribological properties of SLA (Stereolithography Appearance) manufactured samples is presented. Three preliminary curing times of 5, 10 and 15 s were selected for SLA manufacturing. The materials' friction, hardness and capacitance values were determined by ball cratering, Brinell method and electrochemical impedance spectroscopy, respectively. The obtained results showed that the mechanical property values changed most significantly after 10 s of preliminary curing, but friction wear and electrochemical capacitance showed greatest change for samples cured for 15 s. This effect may be explained by the domination of elongation of molecular chains in the first 10 seconds of preliminary curing and the gradual increase of branching processes during the next 15 s. [ABSTRACT FROM AUTHOR] more...

Brake lining performance is influenced by configuration of friction material, functional speeds, load, and temperature. Asbestos friction materials are injurious to human health and, therefore, replacement is needed, hence an alternate material with desired tribo-mechanical properties is to be investigated. In this paper, the wear characterestics of two asbestos-free friction materials sliding against grey cast iron disc were investigated. A metallic based (viz:AF-22) and fine brass based (viz:CL-3003) were prepared by compression moulding process that required pin samples. Wear experiments were performed using a Pin-on-disc tribo-tester. The wear rates were compared under various temperature, sliding speed, and pressure conditions using Taguchi's L9 orthogonal array. The wear rate of AF-22 was observed between 2.01 to 2.17 mm³/N.m., and for CL-3003 (1.49 to 1.66 mm³/N.m). Ranking of the parameters based on the experimental findings and the S/N ratio analysis was done. Temperature is the most influencing parameter, i.e. 82.96% for AF-22 and 87.95% for CL-3003 material. The EDS technique was used to understand material composition. At various magnifications, SEM images of brake pad materials were investigated. Further investigation under in-situ condition is recommended for these materials. [ABSTRACT FROM AUTHOR] more...

The aim of our research was to indicate the suitability of metallurgical slags (two blast furnace slags and one steel furnace slag) as the components of Cu-free friction materials. The base mixture consisted of nine components including phenolic resin, graphite, tin sulphide, steel and aramid fibers, iron powder, a mixture of barite with calcite, and vermiculite. To this base mixture, the slags with a particle size below 0.1 mm were added individually in the amount of 20 wt.%. A base friction mixture with alumina in the amount of 20 wt.% represented the reference. Samples for the friction-wear tests were produced in the form of pins by hot press molding. The prepared pins were tested using a pin-on-disc tester in a drag mode at the pressure of 1 MPa and a constant sliding speed of 1.51 m/s for 90 min. The samples with slags exhibited slightly lower values of steady-state friction coefficient compared to the reference composite with alumina, and at the same time produced lower wear particle emissions. The particle concentration was reduced for the samples with slowly cooled blast furnace and steel furnace slag. The results obtained indicated steel furnace slag as a promising component of Cu-free friction composites. [ABSTRACT FROM AUTHOR] more...

Purpose: The purpose of this paper, brake friction material samples with six different contents were produced using three different fiber types consisting of variable proportions of huntite mineral and basalt, glass and steel fibers. The friction properties and formation of the transfer film in these friction materials were investigated. Design/methodology/approach: Friction materials were produced using a hot molding method from materials containing 10%–15% huntite in varying proportions, consisting of basalt, glass and steel fibers. The densities and hardness values of the samples were measured. Friction tests were performed using a brake pad friction material tester to determine tribological properties. After the friction tests, microscopic examination of the sample surfaces was performed using scanning electron microscope (SEM) and three-dimensional (3D) surface profilometer devices. Findings: Huntite mineral content and fiber type affected the friction coefficient. With an increase in the amount of huntite, the friction coefficient increased in the friction material samples formed with glass and steel fibers. The fiber type and amount of huntite also affected the transfer film formation. The surface roughness values of all the friction materials decreased with an increase in the amount of huntite. The surface roughness values of the samples with glass fibers were higher than those of other samples. Originality/value: The importance of using huntite minerals and different fiber types in automotive brake friction materials is emphasized. This will help industrial companies and academics study the tribological properties of friction materials. [ABSTRACT FROM AUTHOR] more...

Purpose: The main purpose of this study in the field of automotive brake friction material is to find an effective material to replace the environmentally hazardous copper in the brake pad formulation. Design/methodology/approach: Cu is used as functional filler in various forms in the friction material formulation. Because of its hazardous impact to the aquatic life, a suitable replacement of Cu is the main focus of this research. Three novel friction composite materials using ground granulated blast furnace slag (GGBFS) as a suitable alternative for Cu were developed by increasing its Wt.% from 5% to 15% in the step of 5%. Findings: The physical, mechanical and chemical properties of the developed friction composites were tested as per the industrial standards. The tribological properties were analyzed as per SAE J661 standard using the chase test rig. Initial studies revealed that the friction composite having 5% GGBFS exhibited better physical, mechanical and chemical properties with excellent frictional performance having minimal fluctuations even at higher temperatures. Nonetheless, the results showed that the friction composite containing 15 Wt.% GGBFS revealed a better wear resistance property compared with the other two composites due to the tribo lubricating layer formation at the frictional interface. Scanning electron microscope analysis was performed to understand the wear mechanism and tribo layer formations through topography studies. Originality/value: This paper explains the influence of GGBFS as a replacement of barytes in brake pads formulation to enhance the tribological performance. [ABSTRACT FROM AUTHOR] more...

Purpose: This paper aims to investigate the tribological performance, i.e. abrasion resistance, friction coefficient and wear rates, of self-lubricated water conditioned polyamide6/boric oxide composites. Design/methodology/approach: Polyamide6 and polyamide6/boric oxide self-lubricated composites were immersed in water for 15 days to analyze the effect of water conditioning on friction, wear and abrasion resistance. Tribological testing on pin-on-disc tribometer and abrasion resistance testing on TABER abrader were performed to see the friction coefficient and wear rates of materials. The scanning electron microscopy (SEM) characterizations were performed to analyze the wear tracks. Findings: Tribological testing results revealed the loss in abrasive resistance, but there was an improvement in frictional coefficient and wear rates with steel after water absorption. The SEM images clearly show less depth of wear tracks in water-conditioned materials than dry ones. Water conditioning was found supportive in the formation of smooth lubricating transfer film on steel disc during the tribological testing. Originality/value: The tribological behaviour of polymer composites is different in dry and in high humidity or water conditions. Experiments were performed to investigate B2O3 solid lubricant filler effectiveness on tribological behaviour of water-conditioned polyamide composites. Bonding between polyamide6 and water molecules plus the formation of orthoboric acid was found advantageous in decreasing the friction coefficient and wear rates of composites. [ABSTRACT FROM AUTHOR] more...

The wear of a friction material applied on drum brakes of commercial vehicles was investigated in this work. Specimens were manufactured and cycled on a Chase-type machine at different levels of applied normal load and temperature. A standard test procedure was used as a reference for the definition of the test conditions and measurement methods. The wear of the specimens revealed that a wear rate based on mass loss should be used to characterize the wear behavior of friction materials. This wear rate was called specific wear mass. Inspection of topography and friction behavior showed that mechanical load plays an important role in stabilizing the friction coefficient. Analysis of the material loss quantities and density showed that excessive temperature irreversibly affects the structure of the friction material. A method for prediction of the durability of friction materials applied on drum brakes, based on the specific wear mass and the energy dissipated during the braking cycles, was presented. [ABSTRACT FROM AUTHOR] more...

The Taguchi-Grey relational method was used to determine the optimal setting of wear behavior of Al–Si–Mg alloy reinforced with synthesis carbon nanotube derived from rice husk (CNTs-derived RH) and periwinkle shell nanoparticle (PWSnp) nanocomposites for friction material. The applied load, sliding speed, sliding time, and abrasive mesh were the wear parameters, and coefficient of friction and wear rate were used in the multi-response for the study. The minimum coefficient of friction and wear rate were obtained at the optimal parameter of applied load (20 N), sliding speed (1.5 m/s), sliding time (60 min), and abrasive mesh (1000 grit). The coefficient of friction rises as applied load increases and decreased with an increase in sliding speed, sliding time, and abrasive mesh. The Taguchi-Grey approach can be used in multi-response optimization of Al–Si–Mg/CNTs-derived RH and PWSnp nanocomposites since the experimental values are within the limit of predicted values. Hybrid nanocomposites of A356 alloy 0.5 wt% CNTs derived from RH and PWSnp can be used in brake applications. [ABSTRACT FROM AUTHOR] more...

Coefficient of friction values, wear and surface roughness differences are revealed using pin-on-disc test apparatus examinations under three pv loads, where samples are cut from a reference, unused, and several differently aged and dimensioned, used, dry friction fiber-reinforced hybrid composite clutch facings. Tests are characterized by surface activation energy and separated into Trend 1, 'clutch killer', and 2, 'moderate', groups from our previous study. The results reveal that acceptable, 0.41–0.58, coefficient of friction values among Trend 1 specimens cannot be reached during high pv tests, though the −0.19–−0.11 difference of minimum and maximum pv results disappears when activation energy reaches 179 MJ. The maximum pv friction coefficient can decrease by up to 30% at working diameter due to clutch killer test circumstances, as 179 MJ surface activation energy is applied, while by moderate tests such losses can only be detected close to 2000 MJ energy values among small-sized facings. Besides that, Trend 2 specific wear values are the third of trend 1 results at inner diameter specimens. Compared to reference facing values, specific wear results at working diameter under maximum pv decrease by 47–100%, while increasing specific wear during lifetime can only be detected at the inner diameter of facings enduring clutch killer tests or that are small-sized facings. Among Trend 1 radial and tangential Ra delta results, inner diameter samples provide more decreasing surface roughness data, while by Trend 2 values, the opposite relation is detected. Apart from the effects of activation energy, mileage and driver profile, facing size and friction diameter influence is also revealed. [ABSTRACT FROM AUTHOR] more...

The lack of knowledge on the link between the manufacturing process and performance constitutes a major issue in brake lining development. The manufacturing process of organic brake friction composite materials includes several steps (mixing, preforming, hot molding and post-curing), which define their final microstructure, properties and performances. This study focuses on the effect of mixing duration on the microstructure, properties and tribological behavior of organic friction composite materials. The adopted methodology is based on simplified formulations effective in limiting synergistic effects by reducing the number and size distribution of constituents. Two simplified materials are here developed according to the mixing duration of the constituent introduction sequence. The microstructural characteristics are studied using 2D and 3D analyses, and then correlated with the thermophysical and mechanical properties. Wear mechanisms and tribological behavior are studied in relation to the microstructure and properties of the materials. The results show the effect of mixing duration as regards particle distribution and fiber arrangement. The distribution and size of fiber entanglements contribute to the formation of carbonaceous particle clusters, which create bulk bridges improving thermal conductivity. Moreover, the arrangement of rock fibers affects density, porosity and thermo-physical properties. In addition, the mixing disrupts the cohesion of fiber bundles with the matrix, affecting compressive modulus and wear behavior. This microstructural defect also fosters abundant third-body source flow, which disturbs the tribological circuit and behavior. Porosities induced by fiber entanglements, having a large and irregular size and distribution on the frictional surface, result in low wear resistance and alter the frictional stability. [ABSTRACT FROM AUTHOR] more...

This work aimed to analyze the properties of the experimental ABC100.30 powder material under friction on various structural steels without the use of a lubricant. Tribological tests were performed at constant load and sliding speed for various sliding distance values. The experiments revealed that the studied powder material had the best tribological properties when in contact with steel grade 20. In this case, the friction process was characterized by low values of volumetric and linear wear of the rubbing bodies, as well as a minimum average friction coefficient. The ABC100.30–steel grade 45 friction pair had the highest friction coefficient values and high linear and volumetric wear values. The friction process on steel 30HGSA was accompanied by the maximum wear of the investigated material; however, it was characterized by low friction coefficient values and minimum amplitude of fluctuations. [ABSTRACT FROM AUTHOR] more...

Aluminum alloys are well known light-weight alloys and very interesting materials to optimize the strength/weight ratio in order to reduce automotive vehicle weight, fuel consumption and CO 2 emissions; unfortunately, they are also relatively soft and therefore cannot be used for high wear applications. The aim of this work was to develop an aluminum alloy brake disc with wear-resistant SiC particle reinforced aluminum matrix composites (SiC/Al) joined on to its surface. Different approaches based on brazing or shrink fitting joining technologies were used to join SiC/Al to the aluminum alloy surface. A functional graded structure was built by brazing thin layers of aluminum matrix composites reinforced with progressively higher amount of SiC particles by using a Zn–Al based alloy as joining material. Several samples were prepared by shrink fitting and brazing: 40 mm x 40 mm x 10 mm samples and a 100 mm diameter brake disc with 68% SiC particle reinforced Al matrix surface and aluminum alloy A365 body. Tribological tests demonstrated that an aluminum alloy brake disc with wear-resistant SiC particle reinforced aluminum matrix composites (SiC/Al) brazed on its surface is a promising technical opportunity. [ABSTRACT FROM AUTHOR] more...