Performance Of Friction Materials Research Articles

Braking Performance of Copper-Based Friction Materials Reinforced by AlCoCrFeNi High-Entropy Alloy

It is essential to improve the braking performance of friction materials for high-speed trains. Copper-based friction materials reinforced with AlCoCrFeNi high-entropy alloy (HEA) contents of 0–40 wt% were prepared by powder metallurgy, and the braking performance of these materials at braking speeds of 40, 80, 120, and 160 km/h was investigated. The composition of AlCoCrFeNi HEA particles changes due to the elemental diffusion and alloying between AlCoCrFeNi HEA particles and the copper matrix during sintering. With the AlCoCrFeNi content increasing, the amount of interfaces between AlCoCrFeNi particles and Cu matrix increases and the bending strength of the materials decreases, owing to the formation of oxides. The friction coefficient, braking time, and absorbing power of copper-based friction materials can be significantly improved by adding AlCoCrFeNi particles. However, the improvement in their wear resistance is not significant. The spalling pits and oxides are detected on the worn surfaces. The dominant wear mechanisms of copper-based friction materials are spalling and oxidation.

Comparative assessment of the performance of friction materials based on different agricultural wastes

The composition of friction materials is being revolutionised to exclude contentious components. This work comparatively used palm kernel shells, maize husks, cocoa bean shells and melon shells separately with seven other component materials to achieve novel friction materials. Friction and wear of the friction materials were measured using the test rig designed and constructed in-house for this research. Results showed that the maize husk-based friction material performed greatest in terms of thermal stability, wear, porosity and water absorption. Their thermal stability level indicates suitability for use in low-speed passenger cars and other allied braking applications. Using the selected agricultural residues in place of the contentious components in traditional friction materials would potentially solve health and environmental safety challenges.

Tunable Thermal, Mechanical, and Tribological Properties of Polybenzoxazine-Based Composite for Vehicle Applications

In this study, a series of composites comprising polyether ether ketone (PEEK) and carbon fiber (CF)-reinforced polybenzoxazine for high-temperature friction materials for vehicle brake applications were developed using a high-temperature compression molding technique. The objective of this research was to systematically investigate the thermal, mechanical (tensile and flexural), and tribological performance of friction materials made from polybenzoxazine-based composites by varying the PEEK/CF mass ratio. Our study reveals the substantial improvement effect of the increased content of PEEK fibers on the thermal conductivity, the coefficient of friction, and the friction strength of the polybenzoxazine-based composite materials. Meanwhile, the introduction of carbon fibers was found to have a monotonic positive effect on the mechanical (tensile and flexural) properties and wear performance of the polybenzoxazine-based composites. The polybenzoxazine-based composites exhibit high mechanical strength, with a tensile strength of 50.1–78.6 MPa, Young’s modulus of 10.2–24.3 GPa, a flexural strength of 62.1–88.3 MPa, and a flexural modulus of 13.1–27.4 GPa. In addition, the polybenzoxazine-based composite with a PEEK/CF mass ratio of 75:25 exhibits a high and stable coefficient of friction (0.33) and a specific wear rate (1.79 × 10−7 cm3/Nm at room temperature). Subsequent to the wear test at ambient temperature, the worn surfaces of five polybenzoxazine-based composite samples with various PEEK/CF mass ratios were studied using electron microscopy technology (SEM). The observation of small cracks and tiny grooves on the worn surfaces indicates a combined abrasive and adhesive wear mechanism of the material. Our experimental results clearly reveal superior mechanical properties and excellent tribological characteristics. As a result, these composites show promising potential for the application of friction materials in terms of vehicle braking system applications.

Effect of blending cashew oil modified phenolic resin and nitrile rubber on thermal, mechanical, and tribological performance of friction materials

AbstractThis study aims to investigate the effects of blending cashew nutshell oil modified phenolic resin and nitrile rubber (NBR) on the thermal, mechanical, and tribological performance of brake friction materials. The friction materials, which have a total binder of 25 wt% and different ratios of cashew nutshell oil modified phenolic resin and NBR, were prepared by hot press molding process. The experimental results show that NBR is beneficial to improve the hardness and compression modulus of the brake friction materials. The coefficient of friction (COF) is proportional to the wear rate, when the ratio of cashew nutshell oil modified phenolic resin and NBR is 13:12, the friction material has good heat resistance and exhibits excellent friction stability in the braking process, and the COF is steady between 0.420 and 0.448 at different braking speeds, while the wear resistance of material is optimal. The worn surfaces of the friction materials were examined by scanning electron microscope, and it was determined that the friction film is predominantly secondary plateaus, which can stabilize the COF and reduce the wear rate.

Performance analysis of automotive braking friction materials based on surface roughness

The traditional friction material performance analysis method has the problem of high wear rate. Therefore, this paper proposes a performance analysis method of automobile braking friction material based on surface roughness. The calculation formula of material friction is described by classical friction law, the material performance analysis function is constructed according to Mamdani fuzzy algorithm, the influence function of friction coefficient is determined through the optimal fusion position constraints, and the multi-objective function model is constructed according to surface roughness to analyse the performance of automobile braking friction materials. The results show that the friction coefficient of the material is 0.38 at 200°C. When the service life of the friction material is 150 days, the wear rate of the friction material is 0.22%. This shows that this method can improve the friction performance of automotive braking friction materials, which has a certain practical significance.

Influence of contact pressure and velocity on the brake behaviour and particulate matter emissions

In this work, the braking performance and the emission behavior of airborne wear particles of a low-metallic and NAO friction material have been investigated using a reduced-scale dynamometer, adapted for emission measurements. A specific braking cycle has been developed to assess the influence of velocity and pressure on the tribological performance of friction materials sliding against a cast iron disc. The adopted brake cycle consists of a factorial design of blocks of repeated brake stops, where each block was intercalated with a so-called reference block, meant to recover the initial characteristics of the sliding surfaces. A progressive stabilization of the tribological parameters was observed during the blocks featuring a higher initial velocity. The relevant values of these parameters would depend on the extension of the secondary plateaus in the friction layer. At high pressure and velocity, the low-metallic friction material exhibited a higher wear rate and lower friction coefficient than the NAO material, although the NAO material displayed a weaker recovery behavior regarding the friction coefficient. The emissions of the NAO material were found to be lower and more stable than the low-metallic material. In general, the emissions were found to be correlated with the initial brake velocity mainly, through a cubic relationship, whereas the emissions did not show a clear dependence on contact pressure.

Исследование структуры и свойств фрикционного композиционного материала на основе железной матрицы

The continuous increase in the speed and load of railway transport operating in a wide range of climatic zones of the Russian Federation creates a need to develop new friction materials with the improved performance properties that can ensure high functioning reliability of the electric switch mechanisms. The paper presents the results of the study of the microstructure, physical, mechanical, and operational properties of a new material for friction inserts based on an iron matrix for the switch gear clutches. The new material composition includes such components as Fe, Cu, BaSO4, SiO2, C, and Zn. The authors propose a technique for selecting materials with the specified performance properties based on the results of the research carried out using the experiment factorial planning. For this purpose, the authors carried out the studies and established a relationship between the values of microstructure indicators, physical, mechanical and operational properties of the materials with different quantitative composition of components. The grain boundary density was proposed as an indicator of the dissipative properties of the material, and the possibility of its application as a structural parameter for evaluating the friction material performance characteristics. To assess the friction material performance characteristics, which determine the possibility of its application as a part of the friction clutches of the electric switch mechanism, the authors proposed a new parameter – the endurance period . Another service property was the deviation of the friction coefficient ƒ values in the range of values of the clamping force of the electric switch mechanism. According to the results of bench tests of a new friction material within the friction clutches of the electric switch mechanism, the authors identified a high wear resistance of the material and the possibility of its use in severe climatic conditions. The proposed testing technique allows predicting the performance properties of new materials at the stage of studying the microstructure based on the obtained dependences, which can significantly narrow the search range.

Interfacial characteristics between mineral fillers and phenolic resin in friction materials

Mineral fillers are indispensable constituent part of friction materials, which are capable of improving and stabilizing coefficient of friction, decreasing wear, enhancing thermal conductivity and reducing costs of friction materials, in addition, decreasing the noise in brake application. Based on their roles in the friction materials, mineral fillers are classified into abrasives, lubricants, functional fillers, and space fillers. Herein, four typical commercial mineral fillers, namely quartz, graphite, expanded vermiculite, and barite were studied for revealing their effects on the performance of friction materials. The composition, thermal stability, structural characteristics such as surface area, pore volume, and distribution of the pore size, and thermal conductivity of these mineral fillers were researched mainly by X-ray diffraction (XRD), differential scanning calorimetry and thermogravimetry (DSC-TG), N2 adsorption–desorption isotherms, and thermal conductivity tester. Moreover, in order to illustrate the interfacial characteristics of mineral-based in friction materials, four ideal brake pads only consisting of mineral filler, BaSO4 and phenolic resin were prepared. Microstructure and combination of mineral fillers and phenolic resin were investigated by scanning electron microscopy (SEM), polarizing microscope, and Fourier transformation infrared spectroscopy (FTIR). The results showed that different types of material fillers had special functions for friction materials, and they combined with phenolic resin mainly in a physical way.

Mechanical properties of brake pad composite made from candlenut shell and coconut shell

Development of technology, driving a lot of demand for materials that are cheaper, durable, and environmentally friendly for various purposes, especially in the automotive field. The most important safety feature of any vehicle is its braking system. The ability of brakes is to provide safe and repeatable stopping, which is related to safety of automobiles and human. In this study, candlenut shells (CdNS) and coconut shells (CNS) are used as composite materials in the manufacture of brake linings. The presented research work investigates / explore the mechanical properties and physical of brake pad composites formed candlenuts shell (CdNS) and coconut shell (CNS) composite and wear performance of friction materials. The specific wear rate generally increases with the increase in applied load and sliding speed for all compositions.

Tailoring friction interface with surface texture for high-performance ultrasonic motor friction materials

Abstract Interfacial issues have always been the top priority of tribology which directly affect tribological performance of friction materials and output characteristics of Ultrasonic Motors (USMs). Therefore, from the perspective of bionics, a series of surface textures with different parameters were designed to regulate friction interface. The tribological properties of textured friction materials were systematically analyzed. The results found that tribological performance was affected by positive and negative aspects. Consequently, there is an optimal parameter in the case of the best tribological behavior. The optimal parameter was obtained by virtue of orthogonal experimental design and matrix analysis based on mathematical statistics. Additionally, the energy conversion efficiency of USMs with textured friction materials compared to untextured samples increased by 29%.

Resin Matrix Brake Materials Reinforced by Nano-Al2O3 for Mining Equipment

To verify the effect of Al2O3 particle content and size as an abrasive on resin matrix friction materials for mining equipment, the tribological performance of friction materials was studied by using a blockon- ring tribotester over a wide range of applied load and sliding speed. The testing conditions simulated brake conditions of mining equipment. The antiwear property of nano-Al2O3 was superior to that of micro- Al2O3 for friction materials. The friction coefficients of specimens increased with the increase of nano-Al2O3 content. The wear rates decreased with increasing nano-Al2O3 content. The wear rates of specimens containing nano-Al2O3 was about 2–8 times lower than that of specimen with micro-Al2O3. The specimen with 10.5 vol% nano-Al2O3 showed the best tribological properties. The wear mechanism of specimens with nano-Al2O3 was abrasive wear and plastic deformation.

Formulation Optimization of Friction Material with Golden Section Approach

ABSTRACTThe formulation of boron phenolic resin (BPR)-based nonmetallic friction material was optimized with a Golden Section approach. Eight ingredients were selected as raw materials and divided into three groups: fiber (aramid pulp and K2Ti6O13), filler (nitrile rubber, vermiculite, potash feldspar, graphite, and BaSO4), and resin (BPR). The optimization of formulations was performed in three steps: (1) finding the optimal proportion of each fiber and filler within their groups; (2) optimizing the proportion between fibers and fillers; (3) searching for the optimal volume fraction of resin. The friction coefficient and specific wear rate of composites were chosen to evaluate the formulation. After performing 18 formulation experiments with an MRH-3-type ring-on-block test rig measuring the tribological performance of friction materials, the optimal formulation (F14) was eventually obtained with moderate μ and low specific wear rate.

Influence on Friction Material Performance of Nano-MMT Composites of PF by <i>In Situ</i> Method

Mass fraction of 1.5%, 3% of the nanomontmorillonite (MMT) were separately added in the phenol prepolymer, phenolic resin/ MMT was synthesized by in-situ method (it is called PF/M). The PF/M was carried out TG analysis using thermal analyser, and the synthetic resin PF/M were as new resin matrix to prepare semimetallic friction material, tribological performance test was carried on XD-MSM fixed speed type friction-wear testing machine in accordance with the GB_5763-2008. The results show that the heat resistance of composite PF/M and tribological performance of friction material are best when nanoMMT is 3% in the resin, the Carbon residue rate of PF/M is an increase of 37% compared with PF without nanoparticles at 600°C, thermal recession temperature of sample by the preparation of PF/M increases above 100°C, and it has stable friction coefficient, overall wear rate decreases 26%, especially in high temperature stage at 350°C, the wear rate decreases significantly, its wear rate decreases 30%.

Optimized selection of metallic fillers for best combination of performance properties of friction materials: A comprehensive study

Metallic fillers are considered as very important and almost indispensible in non-asbestos organic (NAO) friction materials as they contribute to the performance properties in various ways. In spite of the awareness of the fact that their type, size, shape, amount, and combination control the performance of friction materials, hardly any systematic efforts are devoted in this direction. Authors in their earlier studies have highlighted some of the aspects in this area. The present paper has focused on very systematic and in depth investigations on these aspects by investigating the role of three different metallic fillers with variation in amount, shape, and size on the performance properties of NAO brake-pad materials. Two series of composites named P (powdery) and F (fibrous) were developed in such a way that the variation in metallic fillers was managed as; three types (copper, brass and iron) and three amounts (0, 10 and 20wt%). Composites were characterized for physical, thermal, mechanical and tribological properties (on brake inertia dynamometer) as per the standard industrial practice. It is observed that the inclusion of metallic fillers enhanced the performance properties of composites significantly. Improved thermo-physical properties especially thermal conductivity of composites played an important role in the performance properties as copper powder based composites showed best tribo-behavior followed by brass and iron powder. In some properties 10% filler loading proved most promising while for others 20% proved beneficial. From shape point of view, powdery fillers had a clear edge over fibrous. Overall, 10% loading of copper powder proved promising in most of the properties, while composite without metallic fillers proved poorest.

Effects of bamboo fibers on friction performance of friction materials

The mechanical properties of bamboo ( Phyllostachys heterocycla) fiber were evaluated. The friction and wear performance of the bamboo fiber-reinforced friction materials (BFRFMs) were tested on a constant speed friction tester. The results showed that the friction coefficient of BFRFMs (reinforced with 3 wt.%, 6 wt.% and 9 wt.% bamboo fibers) was higher than those of the non-BFRFM with identical ingredients and process conditions during the temperature increasing procedure. The friction coefficient of 12 wt.% BFRFMs decreased with increasing temperature during temperature increasing procedure, but fluctuation appeared at 200°C and then it decreased again with increasing temperature. The friction coefficients of BFRFMs with 3 wt.% bamboo fiber were higher than that with other bamboo fiber contents. Specific wear rate of BFRFMs increased with the temperature increasing during temperature-increasing procedure, and the wear rates of BFRFM with 3 wt.% fiber were lower than that of others. Morphologies of wear surfaces of friction materials were analyzed using scanning electron microscopy (SEM) and the friction characteristics were discussed. The results showed that carbonized bamboo fiber can reduce the specific wear rate and the noise and provide stable friction coefficient.

CAD of Friction Material for Automobile Brake Using Artificial Neural Networks

The brake friction materials in an automotive brake system are considered as one of the key components for overall braking performance of a vehicle. Temperature sensitivity of friction materials has always been a critical aspect while ensuring their smooth and reliable functioning, and that sensitivity need to be constantly optimized. The performance of friction materials at elevated temperatures is defined by their fading performance.In this paper,a group of non-asbestos organic based friction materials containing different relative amounts of the ingredients of aluminosilicate fiber, steel fiber, phenolic resin and Cu powder mostly effecting on the tribological properties of designed brake material were manufactured by compression molding. Dry sliding friction characteristics of composites were tested on a model JF150D-II pad-on-disk type friction tester. A model of feed-forward artificial neural networks (ANN) consisting of four input neurons, six output neurons and one hidden layer, was used for the analysis and prediction of the correlation between material components and friction performance. The input parameters of ANN were the contents of four main components as aluminosilicate fiber, steel fiber, phenolic resin and Cu powder. The outputs were the friction coefficients of brake material against cast iron at six different operating tempetures from 100°C to 350°C. Based on ANN model trained successfully by 25 pieces samples, genetic algorithm(GA) was used to optimize the input parameters of compositions of brake material with the goal of minimizing fluctuation of friction coefficients at 100°C to 350°C. The optimum composition of brake material was obtained. The friction experiments of optimized material showed excellent stability of friction coefficients for automotive brake material as test temperatures increased from 100°C to 350°C. The neural network has impressive potential for solving time-consuming problems for the design of automobile brake material.

Artificial Neural Network for Predicting Wear Properties of Brake Lining Materials

Many factors influence the wear of friction material performance such as formulation, manufacturing condition and operating regimes, and so on. In this paper, the wear rate variation has been modeled by means of artificial neural network, the network have been developed with all these relevant factors taking into consideration. 16 influence factors and wear rate selected as input and output respectly, 16 [10-8]2 1 is regarded as the best architecture of neural network, the Levenberg-Marquardt algorithm is used for training the network. The result shows that the model is valid to predict the wear property, as well as that it is useful for optimizing the formulation and manufacturing conditions, the relatively excellent combination of the ingredients and the appropriate manufacturing condition parameters can be obtained by this approach.

Effect of Nano-AlN on the Friction Performance of Cu-Based Friction Material

The Cu-based friction materials with nano-AlN (n-AlN) particles were prepared by powder metallurgy technology. The friction performance of the friction materials was investigated through test rig. The microstructure and worn morphology were studied through scanning electron microscopy (SEM). The results indicate that the coefficient of the Cu-based friction materials with 0.75 wt % n-AlN is high and stable. Comparing with the traditional friction materials without n-AlN, the wear resistance and heat resistance of the friction materials with n-AlN has been improved by 25 % and 18 %, respectively. The n-AlN particles can reduced the abrasive wear and enhance the wear resistance of the Cu-based friction materials.

Studies on reduced scale tribometer to investigate the effects of metal additives on friction coefficient – Temperature sensitivity in brake materials

▶ New approach defined in this study on RSP proved to have potential to study temperature sensitivity of μ (fade and recovery behavior). ▶ This method has significant advantages such as very limited infrastructure, substantially less testing time and manpower along with extremely low cost as compared to the standard method on full scale dynamometer. ▶ Use of metallic ingredients in NAO friction composites affected all performance properties in a beneficial way. Cu was most effective in boosting TC significantly followed by brass and iron). ▶ Inclusion of metallic fillers enhanced all performance parameters related to friction and wear. Copper which is most expensive filler proved best followed by brass (moderately expensive) while iron powder (cheapest) was least effective in boosting performance of reference composite. ▶ Increased TC of the composites due to metallic fillers was the main reasons for improved friction performance. Standard methods practiced by the industry to evaluate performance of friction materials need huge infrastructure, manpower and time. It is necessary for researchers working in this applied field to develop a different approach to screen the potential of friction materials on reduced scale prototype (RSP) which would rank the materials based on performance. In this paper a new test methodology is reported to study the influence of metallic contents on temperature sensitivity of friction composites on RSP. Three friction composites were developed with identical parent composition (90% by wt.) except metallic filler viz. brass, copper and iron powder (10% by wt.). One more was developed without metallic powder by adjusting 10% amount with barite (space filler). All composites were characterized for physical, chemical and mechanical properties. These were tribo-tested on RSP for friction, wear, fade and recovery behavior as per new test methodology. It was concluded that with use of metal contents, friction and wear performance of composites improved in general. Copper containing composite showed best friction and wear behavior followed brass, while iron powder based composite showed moderate behavior. Thus new test methodology proved very effective to rank the performance of friction composites.

Prediction of brake friction materials recovery performance using artificial neural networks

The brake friction materials in an automotive brake system are considered as one of the key components for overall braking performance of a vehicle. The sensitivity of friction material performance and accordingly brake performance, versus different operating regimes, has always been an important aspect of its functioning. In this paper, the influences not only on the brake operation conditions but also on the formulation and manufacturing conditions of friction materials have been investigated regarding friction materials recovery performance by means of artificial neural networks. A new neural network model of friction material recovery performance, trained by the Bayesian Regulation algorithm, has been developed.