Composite Friction Materials Research Articles

High-temperature tribological evaluation of cobalt-based laser cladded disc for automotive brake systems

This study investigates the high-temperature wear behavior of laser-cladded (LC) cobalt-based Stellite 6 alloy coatings and compares the wear resistance of the cladding layer to the grey cast iron (GCI) substrate material at three different elevated temperatures: 150 °C, 250 °C, and 350 °C. Wear mechanisms at elevated temperatures were analyzed using SEM-EDS and Raman Spectroscopy to understand the material removal processes and degradation for the discs and counterpart composite friction material pins, respectively.The results indicated a significant improvement in wear resistance for cobalt-based alloy cladding at high temperatures. Wear rates were reduced by 5.0 %, 43.0 %, and 16.0 % at 150 °C, 250 °C, and 350 °C, respectively. The LC - brake pin tribo-pair exhibited a continuous increase in friction coefficients (CoF) with an increase in testing temperatures. The wear mechanism for laser-cladded discs exhibited a combination of abrasive and adhesive wear, with abrasive wear prevailing at 150 °C and increased adhesive wear at 250 °C and 350 °C. However, at 350 °C, decomposition of phenolic resin and the adhesive wear mechanism, led to brake pin failure. For GCI discs oxidative wear was identified as the predominant wear mechanism. The improved knowledge of wear mechanisms on LC Stellite 6 against composite brake pins, is set to enhance surface modification of GCI for brake disc applications.

Enhanced tribological performance of MoS2 and hBN-based composite friction materials: Design of tribo-pair for automotive brake pad-disc systems

This research comprehensively analyzes the friction and wear behavior of composite friction materials when dry sliding against grey cast iron and laser-clad nickel-based (LC1) and iron-based (LC2) alloy discs. The composite friction materials (P1, P2, P3, P4, P5, and P6) under investigation contain graphite, MoS2, and hBN-based solid lubricant synthesized through the powder metallurgy technique. Tribological tests were conducted using a pin-on-disc configuration to simulate the dynamic interaction between the composite materials and the laser-clad grey cast iron discs. The tests were performed at a 60 N load, 6283.19 m sliding distance, and 2.094 m/s sliding velocity under dry sliding conditions. The results provide valuable insights into the effectiveness of MoS2 and hBN-based solid lubricant composites in reducing friction and wear when in contact with iron and nickel alloy-based laser-clad grey cast iron surfaces. The study elucidates the mechanisms governing tribological behavior, including the formation of friction plateaus and the role of laser-clad counter-discs in reducing wear. The specific wear rate of the nickel-based laser-clad counter disc (LC1) and iron-based laser-clad (LC2) system improved by 63.76 % and 48.32 %, respectively, compared to the conventional grey cast iron disc system when using the hBN-based pin (P6). Additionally, the specific wear rate of the hBN-based pin was 38.49 % lower than the conventional graphite-based pin when sliding against the grey cast iron counter-disc. Artificial Neural Network (ANN) was used to validate the wear rate of the best-performing tribological pair, namely the hBN-based pin (P6) and LC2 counter discs, through supervised learning.

Laboratory Tests on the Possibility of Using Flax Fibers as a Plant-Origin Reinforcement Component in Composite Friction Materials for Vehicle Braking Systems.

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.

Tribological and mechanical exploration of polymer-based hemp and colemanite composite as a friction material

Natural and organic-based composite materials are widely used in many industrial applications due to their low cost, easy recyclability, economic feasibility, and ready availability. In this study, a polymer-based composite friction material consisting of Hemp-Colemanite composition (HCFCo) has been developed for the automotive sector to exhibit lower cost, environmentally friendly characteristics, and suitable friction-wear behaviors. For this purpose, three different ratios (%4, %8 and %12) of HCFCo composites were produced using a coating technique called impregnation process with a specially designed device. During the production stage, homogeneity of the composites was ensured, and then the final shape was given by the hot pressing method. Local based natural materilas frequently used for as anon-asbestos friction materails. For this reason, hemp and colomanited based composites were tested. Properties such as hardness, density, water and oil absorption, friction coefficient, and specific wear of HCFCo samples were examined. In addition, the microstructures of HCFCo composites were investigated to determine the bonding form between hemp fiber and colemanite. The results obtained revealed that the friction coefficient values decreased with an increase in temperature, while no significant change was observed in hardness and density values. Throughout the entire testing process, the friction coefficients varied between 0.14 and 0.29 on average. It was concluded that the developed fiber-reinforced composite can be reliably used in industrial applications and can contribute significantly to innovations in the literature.

Numerical modeling of heat generation process in a disk brake at three thermal contact conditions over an extended braking distance

The article examines the thermal behavior of five newly developed organic composite friction materials combined with a cast-iron railway brake disk during repeated braking. Bench tests were carried out in accordance with the established program, taking into account 15 braking and cooling cycles. In the next stage, the obtained braking parameters were implemented into a 3-D FE model of the brake. The main goal of the study was to determine an influence of important assumptions taken in computer simulations regarding contact conditions, cooling conditions, and the number of required brake components. The contact conditions included: 1) perfect thermal contact, 2) contact of rough surfaces taking into account thermal conductance, and 3) separate heating. The total duration of the analyzed multiple braking reached 7695 s, while the maximum distance covered during this time was 203.1 km. The results of numerical calculations were compared with experimental data obtained on the full-scale dynamometer test stand.

Selection of automotive brake friction composites reinforced by agro-waste and natural fiber: An integrated multi-criteria decision-making approach

The aim of this study is to develop a method for selecting and ranking automotive brake friction composite materials made from agro-waste and natural fibers. This is achieved by using an integrated multi-criteria decision-making methodology. Consequently, six composite samples are produced by reinforcing rice husk, rice husk ash, and Grewia optiva fiber. These samples are then assessed for their frictional properties using a laboratory-scale brake tribometer, in accordance with the requirements outlined in SAE J2522 standard. The selection criteria are based on the analyzed tribological parameters, which include friction coefficients, wear, and friction fluctuations fade-recovery performances. The CRITIC (criteria importance through intercriteria correlation) method was used to determine the importance of criteria for performance evaluation. Based on CRITIC analysis, the average friction coefficient (0.1592), recovery-3 (0.1363), friction fluctuations (0.1347), and performance friction coefficient (0.1240) were identified as the key criteria. The use of MARCOS (measurement of alternatives and ranking according to compromise solution) for ranking assessment reveals that composite materials reinforced with rice husk ash exhibit the most favorable tribological characteristics. The validation of the ranking using different decision-making tools demonstrates the reliability and effectiveness of the proposed approach.

Investigation on tribological behaviour of copper-free composite friction material under dry sliding at high-temperature

ABSTRACT This research uses a rotary pin-on-disc tribometer to explore the friction and wear behaviour of a copper-free semi-metallic friction composite over various operating temperatures, 25 °C, 150 °C, 250 °C, 350 °C, and 450 °C. The tribological performance of copper-free semi-metallic specimens is significantly affected by heat degradation. It was found that at 450 °C, severe wear of the pin specimen occurred. The friction layer coverage gradually decreased at ≥ 250 °C. The composite pin’s wear rate was found to increase 13.26 times from 450 °C to 25 °C, whereas the disc wear rate at 450 °C was 0.86 times the wear rate at 25 °C for the loading condition of 60 N load, 2.09 m/s sliding velocity and 6283 m sliding distance. Micro-ploughing was the primary wear process below and at 150 °C, whereas groove development, delamination, and severe adhesion dominated above 150 °C.

Role of copper and zinc additives in the stiction phenomenon of automotive braking systems

AbstractThe braking system of a motor vehicle is a multi‐material system, subjected to various aggressive conditions. Corrosion of the brake disc during stationary periods can determine the onset of a high adhesion force (stiction) capable of compromising the reliability of the braking system during vehicle motion. The purpose of this work is to study the effect of the introduction of Cu and Zn in the friction material composition. This effect was investigated through electrochemical measurements (electrochemical impedance spectroscopy, potentiodynamic polarization, and stiction tests), conducted using an electrochemical cell simulating the parking brake, complemented by the examination of the brake disc and pad surfaces and water absorption tests. The results suggest that porous components, like vermiculite, in the composite friction material led to high contact force. Moreover, 10 wt% of Cu in the friction material does not significantly affect its stiction behavior in our testing configuration. In contrast, 10 wt% Zn in the friction material significantly reduces the stiction propensity by acting with a complex synergistic mechanism combining physical and chemical shielding effects.

РАЗРАБОТКА СПЕЧЕННОГО ФРИКЦИОННОГО МАТЕРИАЛА ДЛЯ ГИДРОТРАНСФОРМАТОРА ГМП САМОСВАЛОВ БЕЛАЗ

The torque converter is designed to transmit mechanical energy from the engine through a circulating fluid flow and automatically steplessly changes, within certain limits, the angular speed and transmitted torque depending on the load on the dump truck wheels. The torque converter makes it possible to achieve low speeds of the dump truck with increased traction on the drive wheels, ensures stable engine operation when the load changes, and also helps reduce dynamic loads in the dump truck transmission. The paper presents the results of a study of the effect of iron-chromium alloy powder ПХ30 (PKh30) on increasing the performance properties of sintered friction material for use in the torque converter locking clutch of a hydromechanical transmission. This is achieved due to the high physical and mechanical properties of PKh30, and the Cr23C6 layer formed during the sintering process with a thickness of up to 6 μm. It is established that the introduction of 10–40 vol.% of PKh30 powder helps to increase the friction coefficient from 0.042 to 0.075, with the maximum content being 28 %. Based on the data obtained, the composition of the composite friction material ФМ-15 (FM-15) was developed and patented. The manufactured friction discs, installed and operated in the hydromechanical transmission torque converter of the BELAZ-7555E mining dump truck with a load capacity of 60 tons, showed high performance properties. The developed composition of the friction material is also used in the friction clutches of the loading and hauling machine MoAZ-40751 with a load capacity of 16 tons and the loading and transport mine machine MoAZ-75851 with a load capacity of 50 tons with an electronic-hydraulic automatic control system. The study of tribological properties was carried out on a friction machine ИМ 58 (IM 58). The morphology of the friction surface was studied on a scanning electron microscope MIRA (Czech Republic) with an INCA 350 micro-X-ray spectral attachment from Oxford Instruments (United Kingdom). Phase composition was determined on an Ultima IV X-ray diffractometer of Rigaku Company (Japan) in CuKα radiation at an X-ray tube voltage of 40 kV, anode current of 40 mA.

Green composite friction materials: A review of a new generation of eco-friendly brake materials for sustainability

Particulate matter (PM) still poses a significant threat leading to air pollution which is responsible for continued damage to human health and the environment. Particulate matter resulting from non-exhaust emissions are considered as viable a source comes mostly from brake pad wear concept. The scientific challenge of this work is to stimulate a new generation of green friction materials to reduce particle emissions having low-environmental impact. The specificity of braking materials, their effects on the environment and human health are studied. To minimize the levels of air pollution, the use of green friction composites collected from natural elements reducing human diseases is discussed. For this purpose, the novel and high-performance friction composite materials synthesized from vegetable and animal waste used as a raw material are reported. The natural powder and fiber treatments, the optimum formulation and the binder materials related to the green friction composites are reviewed. An overview of environmentally ecofriendly green friction materials embedded by reinforcing phases of natural elements exhibiting excellent mechanical and tribological properties are mentioned. Therefore, scientific and industrial efforts should concentrate on the development of green friction materials to minimize the effect of transport related air pollution.

Effect of MoS2 Nanoflakes on Mechanical and Tribological Behavior of Composite Friction Material Fabricated by Pressure-Assisted Sintering

Effect of MoS2 Nanoflakes on Mechanical and Tribological Behavior of Composite Friction Material Fabricated by Pressure-Assisted Sintering

Automotive brake friction composite materials using natural Grewia Optiva fibers

There have been growing concerns over using non-renewable resources while manufacturing goods and related environmental laws worldwide. As part of efforts to reduce dependence on non-renewable resources, the uses of natural resources in brake friction materials are gaining prominence. Therefore, a natural fiber from the Himalayan region, Grewia Optiva, was used in the present study to develop a sustainable material for automotive braking applications. Brake friction composite materials were manufactured with various amounts (0, 2.5, 5, 7.5, and 10 wt%) of Grewia Optiva fiber. The composites were evaluated for physicochemical and mechanical characterization, tribological properties, and noise propensity. The friction performance remains comparable for all composites between 0.41 and 0.44, while a 9–13% reduction in the specific wear rate was obtained for the ≥7.5 wt% Grewia Optiva fiber added to the composites. Fade-recovery performance improved significantly with increasing fiber amount, while friction fluctuations remained the lowest for the composite with 7.5 wt% Grewia Optiva fiber content. At the same time, the minimal stick-slip power was associated with the composite having no Grewia Optiva fiber content. Therefore, a multiattribute decision-making technique was employed to evaluate the overall performance of all the composites suggesting 7.5 wt% Grewia Optiva fiber as the optimal content.

Performance Optimization of Lignocellulosic Fiber-Reinforced Brake Friction Composite Materials Using an Integrated CRITIC-CODAS-Based Decision-Making Approach

A hybrid multicriteria decision-making (MCDM) framework, namely “criteria importance through inter-criteria correlation-combinative distance-based assessment” (CRITIC-CODAS) is introduced to rank automotive brake friction composite materials based on their physical and tribological properties. The ranking analysis was performed on ten brake friction composite material alternatives that contained varying proportions (5% and 10% by weight) of hemp, ramie, pineapple, banana, and Kevlar fibers. The properties of alternatives such as density, porosity, compressibility, friction coefficient, fade-recovery performance, friction fluctuation, cost, and carbon footprint were used as selection criteria. An increase in natural fiber content resulted in a decrease in density, along with an increase in porosity and compressibility. The composite with 5 wt.% Kevlar fiber showed the highest coefficient of friction, while the 5 wt.% ramie fiber-based composites exhibited the lowest levels of fade and friction fluctuations. The wear performance was highest in the composite containing 10 wt.% Kevlar fiber, while the composite with 10 wt.% ramie fiber exhibited the highest recovery. The results indicate that including different fibers in varying amounts can affect the evaluated performance criteria. A hybrid CRITIC-CODAS decision-making technique was used to select the optimal brake friction composite. The findings of this approach revealed that adding 10 wt.% banana fiber to the brake friction composite can give the optimal combination of evaluated properties. A sensitivity analysis was performed on several weight exchange scenarios to see the stability of the ranking results. Using Spearman’s correlation with the ranking outcomes from other MCDM techniques, the suggested decision-making framework was further verified, demonstrating its effectiveness and stability.

An investigation into the physical, mechanical, tribology, thermal and durability performance of commercial brake material for rail transportation

Brake friction materials play a crucial role to enable effective deceleration on the moving rail vehicle. Unfortunately, particulate matters generated by brake wear as well as during the brake manufacturing process are affecting the environment and human health. Due to this, the development of green friction material is important to improve environmental health, safety, and human health. To develop new environmental-friendly friction materials, it is important to understand the commercial brake block material components and their tribological performance. Characterisation techniques such as hardness test, pin-on-disc wear test, durability test, thermogravimetric analysis, morphology, density and porosity were performed on the commercial brake block, the obtained results were then compared with the existing literature. The experiment results showed that the performance of the commercial sample is superior to the available green friction composite materials. This indicates the necessity of a new formulation for the development of green friction brake block material that can give better or similar performance as commercial material. The results from this article can be referenced to develop the new formulation.

Effect of compression molding temperature on the characterization of asbestos-free composite friction materials for railway applications

<abstract> <p>Brake pads significantly affect the braking performance of railways under both normal and emergency operating conditions. In previous studies, brake pads were made using the hand lay-up method and produced the best properties on specimens with epoxy, rice husk, Al<sub>2</sub>O<sub>3</sub> and Fe<sub>2</sub>O<sub>3</sub> compositions of 50%, 20%, 15% and 15%. However, the resulting density does not meet the density standard set by PT Industri Kereta Api Indonesia (PT INKA), which is 1.7–2.4 g/cm<sup>3</sup>. To date, there has been limited research into the utilization of the compression hot molding method for the production of asbestos-free composite friction materials composed of epoxy, rice husk, Al<sub>2</sub>O<sub>3</sub> and Fe<sub>2</sub>O<sub>3</sub> for railway applications. In this study, we aimed to determine the effect of compression molding temperature on the characterization of composite brake pads for railway applications. The brake pad specimens were made of epoxy resin, rice husk, Al<sub>2</sub>O<sub>3</sub> and Fe<sub>2</sub>O<sub>3</sub> with a composition of 50%, 20%, 15% and 15%, respectively. The manufacture of composites in this study used the compression molding method with a pressure of 20 MPa for 15 min holding time. The mold temperature used were 80, 100, 120 ℃. Density, hardness, tensile, wear, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests were performed to evaluate the properties of the specimens obtained. The results demonstrated that an increase in molding temperature improved the characterization of the brake pads, with the best results achieved at a molding temperature of 120 ℃ (SP-3 specimen). SP-3 specimens had the best density, hardness, tensile properties and thermal properties compared to other specimens.</p> </abstract>

Experimental investigation of a novel sleeved member with additional friction dampers

A novel sleeved member with additional friction dampers, which is abbreviated as the frictional sleeved member (FSM) in this paper, was proposed to ensure the stability and greater energy dissipation of compression members in space structures. The FSM consisted of an inner core, an outer sleeve, and additional friction dampers. Two semicircular pipes were fastened by high-strength bolts to obtain the outer sleeve. Friction dampers using composite friction materials were distributed on both sides of the sleeve in the long-axis direction. Cyclic compression-unloading tests of four compression members were completed in this paper. The test results showed that the FSM exhibited the following characteristics compared with an ordinary assembled sleeve member (ASM): comparable lateral-constraint capacity, greater resistance, and greater energy dissipation capacity under tiny axial displacement (0–4 mm). Nonmetallic friction pads had a stable energy dissipation capacity and slight start-sliding displacement, which met the energy dissipation requirements of the FSM under tiny displacements. The additional friction dampers of the FSM had a slight effect on the deformation mode of the inner core, but the resistance and secant stiffness of the specimen were both significantly improved. The outer sleeve of the FSM adopted an asymmetric friction connection, leading to a periodic local increase and an overall decrease in the clamping force of the high-strength bolts. The extrusion between the outer sleeve and the buckling inner core had a negligible effect on the clamping force of the high-strength bolts.

Optimization on tribological properties of natural fiber reinforced brake friction composite materials: Effect of objective and subjective weighting methods

This research aims to study the effect of objective and subjective weighting methods in multi-attribute decision-making (MADM) and then develop a systematic framework for selecting the best natural fiber-reinforced friction composite for automobile braking applications. Therefore, sixteen friction composites with varying weight amounts (5, 10, 15, and 20 wt%) of pineapple, ramie, hemp, and banana fibers were fabricated and evaluated for tribological properties. The experimental results, such as friction coefficient, fade-recovery performance, friction fluctuations, wear, friction stability, and variability aspects, were discussed and considered performance attributes for selecting optimal composition. The results indicated that the incorporation of varying amounts of natural fibers has different effects on the tribological properties, making it challenging to prioritize the performance of the composites to choose the best from the set of composite alternatives. Therefore, EDAS (evaluation based on the distance from the average solution) MADM approach has been applied to pick the best alternative from sixteen natural fiber-based brake friction composites. As an input to EDAS, different types of objective and subjective weighting methods were used to identify the importance of each attribute. These methods include the CRITIC (criteria importance through inter-criteria correlation), entropy, BWM (best-worst method), and AHP (analytic hierarchy process). The results show that the composite alternative with 5 wt% ramie fiber exhibits the optimal tribological properties. The sensitivity analysis and validation reveal the robustness of the results, demonstrating that the same alternative dominates in diverse MADM and weighting conditions.

Friction Performance Improvement of Phenolic/Rockwool Fibre Composites: Influence of Fibre Morphology and Distribution

The size and morphology of reinforcing fibres have a great influence on organic brake friction composite material properties and performance. This research aims to establish the link between friction material microstructure heterogeneity induced by rockwool fibre morphology and distribution and the resulting tribological behaviour. The adopted approach is based on simplified formulations designed to limit synergistic effects by reducing the number and size distribution of constituents. Two simplified materials are developed with different rockwool fibre size and morphology. The first material is elaborated with calibrated fibre balls, and the second one is performed with separated fibres. Friction and wear behaviour are correlated with thermal phenomena in order to reveal wear mechanisms and thus understand the link between microstructural characteristics and the resulting tribological behaviour. It was found that a regular size and distribution of rockwool fibre balls induce better tribological behaviour and enhance wear resistance. Indeed, a homogeneously distributed porosity, which is induced by fibre balls, favours the development and preservation of the load-bearing plateaus in the contact. This, consequently guarantees a stable friction and a reduced wear rate. Consequently, reducing microstructural heterogeneity, resulting from rockwool fibre morphology and distribution, improves the performance of composite friction material.

Influence of ground granulated blast furnace slag on the tribological characteristics of automotive brake friction materials

PurposeThe 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/approachCu 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%.FindingsThe 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/valueThis paper explains the influence of GGBFS as a replacement of barytes in brake pads formulation to enhance the tribological performance.

The Carbon of Swietenia Machrophylla Fruit Peel and Coal Fly Ash as Bio-Composite Brake Ingredients

The eco-friendly brake composite has been still an interesting issue in the development of brake friction materials. Wastes of S. Macrophylla (mahogany) fruit skin and coal fly ash are available as organic ingredients of bio-composite brakes. In this research, we investigated the effects of both ingredients on the brake composite properties which were fabricated using hot isostatic pressing at temperature 200 °C and pressure 5 kN for 3 h. The specimens were prepared in some volume fractions of carbon (2 vol% - 12 vol%). As a result, several tested specimens containing mahogany fruit skin carbon revealed maximum Rockwell hardness 69 HRB, wear 2.49x10-4mm2/kg, and water absorption 2.72 %, while specimens containing coal fly ash showed 78 HRB, 1.1x10-3mm2/kg, and 3.5 %, respectively. The brake composites containing coal fly ash performed better than ones containing mahogany fruit skin carbon. The hardness and wear of these two types of brake composite friction materials meet the minimum criteria required by SAE, JA661, and are close to the quality of the brake pads of two commercial brake composite materials. Water absorption in the brake lining specimens with mahogany leather carbon showed that the addition of the volume fraction caused an increase in water absorption, while the specimen containing coal fly ash showed that the increase in the carbon volume fraction caused a decrease in water absorption.