Search

The hard particles in the copper-based powder metallurgic material of a brake pad for a wind turbine brake falls off and presses into the surface of the brake disc to form abrasive particles under high-speed and heavy-load working conditions. The presence of abrasive particles will produce abrasive wear with micro-scratch and micro-scribe on the copper-based material of the brake pad. The critical scratch depth effect in the abrasive wear process is proposed based on the critical depth effect of the metal removal process at the micro-scale. The abrasive wear is divided into two types: scratch wear and scratch wear, which is proposed according to the comparison of the actual scratch depth and the critical scratch depth. The range of braking speeds and friction coefficients in abrasive wear is determined by the recommended parameters of the disc brake. The ABAQUS2020 software is used to simulate and analyze the micro-scale abrasive wear of a brake pad. The brake strain/stress curves of the brake pad under different brake speeds and friction coefficients are compared and analyzed for two abrasive wear types based on the range of braking parameters, and the key factors affecting abrasive wear are proposed. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental research conducted in the laboratory with the aim of obtaining new composite materials used for automotive brake pads. The friction material consists of seven components; five of them were kept in a constant proportion (60%wt), and two (40%wt) were varied in fraction volume, namely phenolic resin and hemp fiber. For each recipe, the effect of phenolic resin on density, porosity, hardness, thermal stability, and friction-wear characteristics was analyzed. The study indicates that finding the optimal balance between phenolic resin and hemp fiber constitutes an efficient approach in improving friction performance. Additionally, the study demonstrates the viability of organic composite materials in braking applications, as they are capable of meeting the performance levels established by traditional materials. [ABSTRACT FROM AUTHOR]

Copper-based powder metallurgy materials are frequently utilized in fabricating brake pads for high-speed trains. The preparation process involves mixing, ball milling, pressing, and sintering. Among these steps, hot-pressed sintering stands out as a rapid and efficient method that significantly influences the properties and performance of the products. In this study, four samples (S700/S750/S800/S850) were prepared using hot-pressed sintering at various temperatures, as follows: 700 °C, 750 °C, 800 °C, and 850 °C. The mechanical and physical properties of the four samples were tested, and the microstructure and compositions were investigated using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The findings highlighted the close relationship between sintering temperature and the mechanical and physical properties of the samples, as it impacts the porosity and interfacial bonding of the particles. Notably, Sample S800 demonstrated superior mechanical and thermal conductivity. Furthermore, the coefficient of friction (COF), friction heat, and wear rate of the four samples were also tested under different braking speeds ranging from 150 km/h to 350 km/h. The results indicated that the COFs of the four samples remained relatively stable below 300 km/h but decreased notably above 300 km/h due to heat fading. Sample S800 displayed consistent and high COF under varied braking speeds and exhibited the lowest wear rate. The observed wear mechanisms included abrasive wear and oxidation wear. Additionally, the friction test results underscored the close correspondence of the COF curve of S800 with the standard of the Ministry of Railways of the People's Republic of China. [ABSTRACT FROM AUTHOR]

In a brake system, brake friction composites are essential for converting kinetic energy into frictional heat. An optimal brake friction composite should ensure a stable coefficient of friction under extreme operational conditions. This study examines the tribological performance of brake friction composites incorporating potassium titanate fibres and metal sulphide lubricants in standard brake pad formulation. Brake friction composites were engineered by varying the potassium titanate fibre content from 10 to 30 %, while the lubricant mixture (comprising graphite, MoS2, Bi2S3 and Sb2O3) was proportionally adjusted from 27 to 7 %, with the filler and binder concentrations held constant throughout the formulation. The phenolic resin-based composites were characterised for their physical, chemical and mechanical properties in accordance with the IS 2742 (Part 4) standard. The tribological performance of the fabricated composites was evaluated using a rotating drum setup, following the SAE J661 procedure. The worn surfaces of the samples were analysed to identify wear mechanisms utilising scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). The results demonstrated that the optimal combination of potassium titanate fibres and metal sulphide lubricants significantly influences wear resistance and friction stability, with varying degrees of primary and secondary plateau formation observed. This comprehensive characterisation provides valuable insights into the material's behaviour under operational conditions, guiding the development of advanced brake friction composites.

The paper deals with the evaluation of service brake braking of a selected group of vehicles depending on the wear of brake system‘s parts. During the research, the technical condition of brake systems, the degree of wear of brake discs, brake pads, and the measurement of braking forces using a roller brake tester was monitored and evaluated on a sample of 16 intercity buses for a period of three years. The measurement was carried out on 2 selected intercity buses SOR C 10.5 and IVECO Crossway. The maximum braking forces on both axles of buses were measured using a roller brake tester. Then, the percentage braking of the vehicle was calculated and compared with the minimum required braking according to applicable legislation. Based on the inspection of technical condition of brake pads and discs, it was possible to detect the wear and tear of these elements of the brake system (which was manifested during the inspection of the vehicle on the roller brake tester), and it was also possible to record the insufficient value of the required minimum braking during the calculation.

Clarifying the relationship between friction area and brake disc temperature is helpful to optimizing the brake pad structure. Aluminium-based brake disc temperature paired with circular friction blocks of different diameters (45, 60, and 65 mm) is obtained by the TM-I-type reduced-scale inertial braking dynamometer at braking speeds 60–160 km/h and braking force 1.66 kN. On the basis, the thermo-mechanical coupling model of friction pair is established to simulate the evolution of brake disc temperature by ADINA finite-element software, and the thermal energy gradient factor is proposed. Results indicate that the numerical brake disc temperature agrees with the measured, validating the numerical model. The friction area caused the difference of braking pressure, which affects the brake disc temperature. The decrease in the friction area accelerates the disc temperature rise and increases the area ratio of high-temperature zone and maximum temperature difference. The influence degree of friction area on the brake disc temperature varies with friction zone. The thermal energy gradient factor can effectively predict the distribution of temperature gradient on the disc surface. [ABSTRACT FROM AUTHOR]

Abstract There has been an increase in research over the past decades into the use of environmentally friendly materials in brake pads, such as natural fibres. This is due to the possibility that natural fibbers could serve as an alternative to the noxious asbestos materials in tribological applications like brake pads. As a result, utilizing the compacting mould technique, an asbestos-free friction material was developed using agricultural waste (coconut shell and oil bean stalk) as a filler element, alongside aluminium dross, metal chip industrial wastes and carbon black. The filler material considered had particles as small as 300 μm, with epoxy resin serving as the binding agent. Using these waste materials can help reduce environmental pollution and the risk to animal and plant life (Preeti et al., Pharma Innov J 7:94–102, 2018; Sajib, A Study on the effects of environmental pollution on human life in the riverbank area of Barishal City Corporation (Kirtankhola River), 2021). This research aimed to replace asbestos in brake pads due to its carcinogenic nature, reducing the health risks associated with manufacturing and using these brake pads. The brake pad materials were cast and produced using square wooden moulds. Four samples were created, comprising the same mixing ratio but varying in reinforcement fibre and particle size, with epoxy resin used as the matrix. Various tests were conducted on these samples, including a water absorption test, specific gravity test, compressive strength test, hardness test, thermal conductivity, SEM and EDX. The developed brake pads underwent microscopic characterization and structural examination using a scanning electron microscope (SEM) fitted with energy-dispersive X-ray spectroscopy (EDX) for elemental characterization. Thermal conductivity was obtained using automated Lee’s Disc apparatus. Comprehensive strength analysis was conducted using a universal testing machine (UTM). The specific gravity tests yielded values for the developed composites in the range of 1.136–1.257, while the commercial brake pad had a value of 2.081, indicating that the produced samples were lighter and less dense. The water absorptivity of the developed samples ranged from 0.95 to 2.174%, while the commercial brake pad had a value of 1.031%. For the hardness tests, at three different loads, the developed values ranged from 16.4HV3 to 19.4 HV3; 26.4HV30 to 28.7HV30; and 25.5HV100 to 29.6HV100, while the commercial brake pad had values of 16.5HV3, 28.4HV30 and 28.2HV100. Sample C (212 μm: coconut shell powder) exhibited the most desirable characteristics with five values: water absorptivity 0.95, compressive strength 120.5 MPa, hardness value 29.6 HV100, wear resistance 0.099 mm/mm3, specific wear rate 1.00 mm3/Nm. The outstanding values were attributed to the chemical composition, particle sizes and good interfacial bonding of the microstructure. The developed brake pads performed favourably when compared with the existing commercial brake pads. The chemical tests showed that the natural fibres bonded well with the epoxy matrix. The thermal and mechanical tests yielded comparable results with the values obtained from the commercial brake pads. Therefore, the developed materials for brake pads can be considered suitable replacements for asbestos brake pads.

Tribological test and hybrid ranking techniques are employed to evaluate brake pads from original equipment manufacturers for Indian passenger cars. The study was conducted for four brake pads designated as OE1, OE2, OE3, and OE4. The assessment integrates the analytical hierarchy process with various ranking methods including Extension Evaluation Method, Complex Proportional Assessment, Preference Selection Index, and Technique for Order of Preference by Similarity to Ideal Solution. Brake pad samples undergo testing according to the standard IS2742 part 1-4 of 1994, generating crucial performance parameters such as performance coefficient of friction, hot coefficient of friction, normal coefficient of friction, fade percentage, recovery percentage, variation in coefficient of friction, wear thickness loss percentage, wear mass loss percentage, and time taken to reach maximum temperature. These performance metrics are technically analyzed and ranked using hybrid ranking techniques to enhance the decision-making process. The results show that OE4, a budget-friendly brake pad ranked first, is the best performer. OE2, a more expensive alternative, is placed second, and OE1 and OE3, which are more affordable possibilities, are ranked third and fourth, respectively. This research serves as a valuable resource for selecting brake pads for Indian passenger cars, especially in scenarios where technical specifications and cost-effectiveness are crucial considerations. [ABSTRACT FROM AUTHOR]

The analysis of the statistical values of wear of brake pads in operation, based on which a wear model was developed, is presented in this paper. This model can be used for predicting the remaining service life of brake pads according to the wagon mileage. The distribution function of wear on the upper and lower parts of the pad was determined, which made it possible to find the main qualitative characteristics, namely, the wear intensity, the γ-percentage wear, and the average pad wear at a specified wagon mileage. The results of the study can be factored for solving complex engineering problems of excessive wear of composite brake pads used for freight rolling stock; they could also help to extend the guaranteed overhaul period and improve the railway traffic safety. [ABSTRACT FROM AUTHOR]

The aim of this research is to obtain the properties of glass powder that has undergone a high energy milling process. The properties studied include thermal properties, microstructure, and chemical composition. Glass powder has been characterized through XRF and TGA testing, as well as microstructural observations by using SEM. XRF testing is applied to obtain information regarding the chemical composition of glass powder. On the other hand, in order to obtain information regarding the thermal properties of glass powder, TGA is carried out. SEM has been used to examine the microstructure of glass powder. The XRF test results show the dominance of SiO2 as the main element contained in glass powder. SiO2 has a weight percentage of 65.58%. The second dominant element is CaO, which has a weight percentage of 21.34%, MgO 4.34% and Al2O3 2.26%. The uniformity of the particle size of glass powder that has been treated with HEM is shown from the micrographic images as a result of SEM observations. Through SEM observations, data on the distribution of glass powder particle sizes has been also obtained with an average of 41 µm. The measurement results have showed that the smallest particle size has been 10 µm and the largest size has been 80 µm. TGA produces data on the stability of SiO2 purity at a percentage of 85% at a temperature of 950 °C. This suggests that glass powder has good thermal properties, and has a homogeneous and regular microstructure. This information is very useful for developing glass powder materials for brake pad composite applications. [ABSTRACT FROM AUTHOR]

Research into converting waste into viable eco-friendly products has gained global concern. Using natural fibres and pulverized metallic waste becomes necessary to reduce noxious environmental emissions due to indiscriminately occupying the land. This study reviews the literature in the broad area of green composites in search of materials that can be used in automotive brake pads. Materials made by biocomposite, rather than fossil fuels, will be favoured. A database containing the tribo-mechanical performance of numerous potential components for the future green composite was established using the technical details of bio-polymers and natural reinforcements. The development of materials with diverse compositions and varying proportions is now conceivable, and these materials can be permanently connected in fully regulated processes. This explanation demonstrates that all of these variables affect friction coefficient, resistance to wear from friction and high temperatures, and the operating life of brake pads to varying degrees. In this study, renewable materials for the matrix and reinforcement are screened to determine which have sufficient strength, coefficient of friction, wear resistance properties, and reasonable costs, making them a feasible option for a green composite. The most significant, intriguing, and unusual materials used in manufacturing brake pads are gathered in this review, which also analyzes how they affect the tribological characteristics of the pads. [ABSTRACT FROM AUTHOR]

There has been an increase in research over the past decades into the use of environmentally friendly materials in brake pads, such as natural fibres. This is due to the possibility that natural fibbers could serve as an alternative to the noxious asbestos materials in tribological applications like brake pads. As a result, utilizing the compacting mould technique, an asbestos-free friction material was developed using agricultural waste (coconut shell and oil bean stalk) as a filler element, alongside aluminium dross, metal chip industrial wastes and carbon black. The filler material considered had particles as small as 300 μm, with epoxy resin serving as the binding agent. Using these waste materials can help reduce environmental pollution and the risk to animal and plant life (Preeti et al., Pharma Innov J 7:94–102, 2018; Sajib, A Study on the effects of environmental pollution on human life in the riverbank area of Barishal City Corporation (Kirtankhola River), 2021). This research aimed to replace asbestos in brake pads due to its carcinogenic nature, reducing the health risks associated with manufacturing and using these brake pads. The brake pad materials were cast and produced using square wooden moulds. Four samples were created, comprising the same mixing ratio but varying in reinforcement fibre and particle size, with epoxy resin used as the matrix. Various tests were conducted on these samples, including a water absorption test, specific gravity test, compressive strength test, hardness test, thermal conductivity, SEM and EDX. The developed brake pads underwent microscopic characterization and structural examination using a scanning electron microscope (SEM) fitted with energy-dispersive X-ray spectroscopy (EDX) for elemental characterization. Thermal conductivity was obtained using automated Lee's Disc apparatus. Comprehensive strength analysis was conducted using a universal testing machine (UTM). The specific gravity tests yielded values for the developed composites in the range of 1.136–1.257, while the commercial brake pad had a value of 2.081, indicating that the produced samples were lighter and less dense. The water absorptivity of the developed samples ranged from 0.95 to 2.174%, while the commercial brake pad had a value of 1.031%. For the hardness tests, at three different loads, the developed values ranged from 16.4HV3 to 19.4 HV3; 26.4HV30 to 28.7HV30; and 25.5HV100 to 29.6HV100, while the commercial brake pad had values of 16.5HV3, 28.4HV30 and 28.2HV100. Sample C (212 μm: coconut shell powder) exhibited the most desirable characteristics with five values: water absorptivity 0.95, compressive strength 120.5 MPa, hardness value 29.6 HV100, wear resistance 0.099 mm/mm3, specific wear rate 1.00 mm3/Nm. The outstanding values were attributed to the chemical composition, particle sizes and good interfacial bonding of the microstructure. The developed brake pads performed favourably when compared with the existing commercial brake pads. The chemical tests showed that the natural fibres bonded well with the epoxy matrix. The thermal and mechanical tests yielded comparable results with the values obtained from the commercial brake pads. Therefore, the developed materials for brake pads can be considered suitable replacements for asbestos brake pads. [ABSTRACT FROM AUTHOR]

Copper-based powder metallurgy materials are frequently utilized in fabricating brake pads for high-speed trains. The preparation process involves mixing, ball milling, pressing, and sintering. Among these steps, hot-pressed sintering stands out as a rapid and efficient method that significantly influences the properties and performance of the products. In this study, four samples (S700/S750/S800/S850) were prepared using hot-pressed sintering at various temperatures, as follows: 700 °C, 750 °C, 800 °C, and 850 °C. The mechanical and physical properties of the four samples were tested, and the microstructure and compositions were investigated using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The findings highlighted the close relationship between sintering temperature and the mechanical and physical properties of the samples, as it impacts the porosity and interfacial bonding of the particles. Notably, Sample S800 demonstrated superior mechanical and thermal conductivity. Furthermore, the coefficient of friction (COF), friction heat, and wear rate of the four samples were also tested under different braking speeds ranging from 150 km/h to 350 km/h. The results indicated that the COFs of the four samples remained relatively stable below 300 km/h but decreased notably above 300 km/h due to heat fading. Sample S800 displayed consistent and high COF under varied braking speeds and exhibited the lowest wear rate. The observed wear mechanisms included abrasive wear and oxidation wear. Additionally, the friction test results underscored the close correspondence of the COF curve of S800 with the standard of the Ministry of Railways of the People’s Republic of China.

Fine particles from vehicles occur in a range of particulate matter (PM) sizes and influence the roadside atmosphere. The contribution of fine dust from automobiles to road pollution has reportedly been extremely high. Researchers have estimated that non-exhaust fine dust originating from brakes, tires, clutches, and road surface wear rate is increasing. Several studies have shown that brake pads account for a significant proportion of non-exhaust emissions. In this study, a friction test using vehicle brake pads was carried out with a friction tester to reveal the harmfulness of brake pad particles by the driver's driving habits. Conditions were made considering the pressure, vehicle speed, and temperature and assuming the amount of deceleration of the vehicle. Particle collection devices were used to analyze the concentration of number and the mass distribution of particles produced in the experiment, with a range from 6 nm to 7.3 μm to gauge the toxicity of particles. The results showed that the number concentration of fine particles tended to increase linearly with changes in vehicle deceleration (braking energy) in the particle diameter region around 0.75–7.3 μm. The number concentration of fine particles tended to increase exponentially in the particle diameter region around 71–120 nm. The rapid occurrence of ultrafine particles in nanometers varied depending on the test conditions. [ABSTRACT FROM AUTHOR]

The paper highlights the results of determining the strength of the brake pad of a freight wagon under uneven loading in operation. The main reasons for the uneven loading on the pad have been found. A mathematical tool for determining the strength of the pad unevenly loaded has been proposed. In the study, the pad is considered to be a rod system loaded with concentrated forces and bending moments. Sensors have been used in order to detect the load state of the brake pads. These sensors have been defined in the simulation software, and they have been placed on the working surface of the pad in the area of its interaction with the wheel. The operation of these sensors was simulated in the simulation software package. The results of the calculation have shown that the stresses in the pad are about 21.1 MPa; thus, they exceed the permissible values by 29%. Therefore, considering the uneven loading of the pad in operation, the strength of the pad is not ensured. To test the obtained results, the strength of the pad was determined using the finite element method. The Coulomb criterion was used for the calculation. It was found that the maximum stresses in the pad were about 19 MPa. These stresses were 21% higher than permissible values and occurred in the back of the pad. The study has proven that the uneven loading on the brake pad in operation can cause their destruction during braking. This may also cause traffic accidents with freight trains during their movement. The results of this study will contribute to the theoretical developments and recommendations aimed at improving the brake system of a freight wagon and rail traffic safety. It is considered that the tensometric sensors will be applied in future experimental tests for comparison and verification of the achieved results from the simulation computations. [ABSTRACT FROM AUTHOR]

The work highlights the results of a study into the dual wedge-shaped wear of composite brake pads for freight wagons. It has been found that the overnormative wear makes the area of a composite brake pad larger in the lower part up to a value directly proportional to the wagon mileage and smaller in the upper part. To assess the braking efficiency of a rail vehicle, a graphical analytical method has been developed; it allows determining the factor of dual wedge-shaped wear of pads depending on the wagon mileage. The results of calculation were verified by comparing two samplings obtained by mathematical and computer modelling. The results of calculation have proven that the hypothesis on the adequacy is not rejected. The results of the study conducted will allow more accurate assessment of the braking efficiency of freight rolling stock to be made, as well as contribute to improving the safety of train traffic. [ABSTRACT FROM AUTHOR]

In this study, the effects of red volcanic tuff, which has different uses in automobile brake pads, on the friction performance of brake pads were investigated in a brake pad testing device. Brake pad containing red volcanic tuff was produced using the hot-pressing method at 150 °C temperature, 15 MPa pressing pressure, and 15 min of pressing time at four different mixing ratios. Nine different materials were used in the production of the samples. The developed samples' friction coefficient, mass wear rate and hardness were determined. Optimum friction coefficient and wear rate performance were obtained in brake pad samples produced with red volcanic tuff. The friction coefficient increased with the increase of the red volcanic tuff ratio. The microscopic analysis of the worn surfaces of the brake pad samples, the friction coefficient of which was determined, was examined by scanning electron microscopy. The hardness of the brake pad sample decreased with the increase in the use of red volcanic tuff in the sample content. The decrease in the hardness of the sample caused the wear rate to be within the standard limits but high in the sample using the highest rate of red volcanic tuff. As a result, the performance of brake pad containing red volcanic tuff is similar to the studies in the literature, and it has been determined that this material can be used in the content of brake pads. [ABSTRACT FROM AUTHOR]

The analysis of the statistical values of wear of brake pads in operation, based on which a wear model was developed, is presented in this paper. This model can be used for predicting the remaining service life of brake pads according to the wagon mileage. The distribution function of wear on the upper and lower parts of the pad was determined, which made it possible to find the main qualitative characteristics, namely, the wear intensity, the γ-percentage wear, and the average pad wear at a specified wagon mileage. The results of the study can be factored for solving complex engineering problems of excessive wear of composite brake pads used for freight rolling stock; they could also help to extend the guaranteed overhaul period and improve the railway traffic safety.

Recently, new brake pads have been developed using sustainable materials that are not harmful to the environment. In this study, the effect of using blue-colored Cupressus arizonica cones was determined as a friction modifier in brake pad composites. Four different samples were prepared by grinding the cone material. The samples’ physical and chemical properties and performances were compared, and finally, their microscopic analyses were visualized by scanning electron microscopy. Maximum friction coefficient and minimum wear rate are required for brake pads. The maximum friction coefficient of 0.39 and the minimum wear rate of the samples containing Cupressus arizonica were obtained in the 0.124X10-7 cm3/Nm BCA3 sample. When the brake pads developed from lignocellulosic biomass were compared, it was determined that the BCA3 sample met the most reasonable performance values.

Contact between the automotive brake pad and the disc is mathematically modelled to estimate the coefficient of friction (COF). The mathematical model is proposed for the prognosis of the COF of brake pad material, by considering the contact mechanics between the interfacing surface and their material properties. The Greenwood-Williamson contact model is applied for rough contact surfaces for the estimation of the real contact radius. A MATLAB program has been formulated for generating the surface of brake pad material by considering its material properties which aid in the analytical evaluation of the COF. The proposed model is further validated with experimentation on pin-on-disc apparatus, as it is considered suitable for friction pad product testing according to previous research. The 25 pins were fabricated as per the ASTM G99 test for testing under varying loads and speeds. The obtained results showed that the range of COF has been between 0.2 and 0.4. The investigation presents an analytical approach for estimating COF and contact radius for brake disc and brake pad, which can be used to design an efficient automotive brake disc-brake pad system under the given load and rotational speed. The artificial neural network (ANN) is modelled for predicting the values of the COF for brake disc-brake pad systems, which can be further used for determining the tribological properties of new friction materials and their compatibility for efficient brake systems.

The work highlights the results of a study into the dual wedge-shaped wear of composite brake pads for freight wagons. It has been found that the over-normative wear makes the area of a composite brake pad larger in the lower part up to a value directly proportional to the wagon mileage and smaller in the upper part. To assess the braking efficiency of a rail vehicle, a graphical analytical method has been developed; it allows determining the factor of dual wedge-shaped wear of pads depending on the wagon mileage. The results of calculation were verified by comparing two samplings obtained by mathematical and computer modelling. The results of calculation have proven that the hypothesis on the adequacy is not rejected. The results of the study conducted will allow more accurate assessment of the braking efficiency of freight rolling stock to be made, as well as contribute to improving the safety of train traffic.

Magnesium metal matrix composites for lightweight brake pad applications are developed in this study. The composites are fabricated by using the powder metallurgy process. The addition of 0.5 wt.% to 2 wt.% Y2O3 (Rare Earth Oxide) used as a reinforcement to the AZ31 Mg composite is investigated. Density, hardness, and tribometer tests are carried out according to the ASTM standards. The friction and wear test of magnesium composites is tested against the grey cast iron disc. FESEM analysis shows the microstructure and morphology of worn surfaces. The elemental mapping result depicts that the elements of Mg, Al, Zn, Y, and O are uniformly distributed in the composite. X-ray diffraction analysis shows the compounds of Y2O3, MgO, ZnO, and Al2O4 are present on the worn surface of AZ31 + 2 wt.% Y2O3 composite. The outcome of the experiment reveals that increasing the proportion of yttrium oxide increases the magnesium composite's density and decreases the porosity. AZ31 + 2 wt.% Y2O3 composite exhibits the highest hardness of 122HV, a stable coefficient of friction, and a lower wear rate compared to AZ31 + 0 wt.% Y2O3 composite. [ABSTRACT FROM AUTHOR]

Brake discs play a crucial role in braking railway vehicles, but the frictional heat generated during the braking process can lead to high temperatures on the disc. Changes in the friction block location on the brake pad result in variations in the temperature distribution across the brake disc. This study aims to optimize the positioning of friction blocks on the brake pad using artificial neural networks (ANN) and the Design of Experiments (DOE) approach based on the Taguchi methodology. The primary objective of this study is to mitigate temperature discrepancies in the frictional heating rate among distinct sectors along a radius from the center of the brake disc. To analyze the temperature variations caused by frictional heat, finite element analysis (FEA) is executed to account for the thermomechanical characteristics of the brake disc. The optimized brake pad, obtained through the ANN, is evaluated based on the temperature and thermal stress applied to the brake disc. The optimized model displays a larger hot band on the brake disc compared to the original model, leading to a more even distribution of thermal stress across the brake disc. In conclusion, the use of optimized pads offers significant performance benefits, resulting in a reduced maximum temperature and thermal stress, thus improving the overall braking performance of railway vehicles. [ABSTRACT FROM AUTHOR]

The brake pad is the key component in the braking system of high-speed railway trains. The running speeds of commercial high-speed railway trains in China can reach higher than 350 km·h−1. The friction coefficient of brake pads is a key factor determining the safety of any vehicle brake, and a high and stable friction coefficient is ideal for ensuring the safety of the braking system. In practical applications, the friction coefficient can vary because of the changes in the working conditions, such as sliding speed, braking pressure, and temperature between contact surfaces. Under severe conditions, such as high-speed braking and overload, the friction coefficient decreases markedly, which lengthens the braking distance and braking time. Based on the friction performance collaborative regulation theory of powder metallurgy friction materials, a Cu-based friction material was designed. The performance of the brake pad was tested on the full-scale dynamometer, and the characteristics of the friction film were analyzed in detail. Results show that the brake pad exhibits high stability of the friction coefficient, low wear loss, and the capability to protect the brake disc. Both the instantaneous friction coefficient and average friction coefficient of the developed brake pad meet the requirements of the TJ/CL307—2019 technical condition. The stability of the friction coefficient is 0.0015. The recession of the friction coefficient from 250 to 380 km·h−1 is as low as 0.027. The average friction coefficient at 380 km·h−1 remains at the relatively high value of 0.35, and the average wear loss is only 0.06 cm3·MJ−1. The excellent friction and braking performance of brake pads can be attributed to the formation of friction films with high strength and toughness and low transfer rate. The friction components with large particle sizes are used as external motion obstacles to nail the friction film. The submicron wear debris in the friction film serves as the meshing point between the friction film and the dual disc to provide friction resistance, thus maintaining the friction coefficient during high-speed braking. Oxides are continuously supplied by adding easily oxidized components, and the nanosized oxides generated by the severe grinding process are used in the dispersion-strengthening phase. The multiscale particles synergistically enhance the dynamic stability of the friction film. The metal oxide layer on the friction surface reduces and stabilizes the friction coefficient and enhances the wear resistance because it prevents metal–metal contact between the brake pad and the brake disc. The fade phenomenon that occurs under high braking speed and overload conditions is effectively prevented.

Copper-based brake pad materials with various fractions of praseodymium oxide and yttrium oxide are fabricated through the powder metallurgy processing technique. The influence of praseodymium oxide and yttrium oxide on the microstructure, microhardness, and tribological characteristics of the fabricated specimens are analyzed. The specimen with desired density, high hardness, wear resistance, and optimal friction coefficient is fabricated with gradient layers (pure copper at the brake pad – brake caliper interface and composite at the brake pad – brake disc interface). The result suggested that as the load gradually increases, the wear rate also increases. The surface morphology, elemental composition, and phase composition of the fabricated specimen and worn surface were characterized using advanced instrumental characterization. [ABSTRACT FROM AUTHOR]

Recently, new brake pads have been developed using sustainable materials that are not harmful to the environment. In this study, the effect of using blue-colored Cupressus arizonica cones was determined as a friction modifier in brake pad composites. Four different samples were prepared by grinding the cone material. The samples’ physical and chemical properties and performances were compared, and finally, their microscopic analyses were visualized by scanning electron microscopy. Maximum friction coefficient and minimum wear rate are required for brake pads. The maximum friction coefficient of 0.39 and the minimum wear rate of the samples containing Cupressus arizonica were obtained in the 0.124X10-7 cm³ /Nm BCA3 sample. When the brake pads developed from lignocellulosic biomass were compared, it was determined that the BCA3 sample met the most reasonable performance values. [ABSTRACT FROM AUTHOR]

Brake pads are an important factor in braking, so it is necessary to study the noise and acoustic characteristics of the brake pads using the acoustic simulation method to obtain sound pressure level results, determine the acoustic characteristics of the simulation, compare the noise results in the simulation with experimental testing. The simulated composite brake lining material uses a composition of hazelnut shell, pineapple leaf fiber, aluminum, polyurethane. Researchers used simulations with the application of the finite element method in the form of 3D modeling to analyze the parameters applied. The parameters are material data, mesh size, acoustic region, physics region, force, mass source. The simulation results of the acoustic characteristics of composite brake linings with a load of 500grams obtained a minimum noise at 500rpm rotation with a distance of 15cm of 3.88dB and the maximum noise occurs with a load of 750grams at 900 rpm rotation with a distance of 5cm of 11.54dB. The average sound pressure level value using the simulation method is smaller than the experimental method at 500rpm, 700rpm, 900rpm, a load of 500grams and 750grams, a distance of 5cm, 10cm, 15cm. This could be caused by parameters that were not included in the simulation, such as vibration on the test equipment, brake pad temperature, setup errors or calibration of experimental method measuring devices. The overall percent error of the simulation results at 500rpm, 700rpm, 900rpm, 500gram and 750gram loads, distances of 5cm, 10cm, 15cm, the result percent error are not up to 12%.

The present study aimed to assess the effect of replacing copper as a multi-functional ingredient in the brake pad material with potassium titanate platelet (PTP) and a particular type of ceramic fiber (CF) copper-free composite. Chase dynamometer tests were conducted to compare a brake padchr('39')s tribological behavior when PTP and CF are added to the composition with that of the copper-bearing pad. The results concluded that PTP and CF demonstrated promising outcomes such as a stable coefficient of friction (COF), lower wear rate, and better heat resistance in copper-free friction composite. Scanning electron microscope (SEM/EDS) analysis was conducted to investigate the role of main elements such as Ti, Fe, K, O, and C on the formation of contact plateaus (CPs) upon the worn surface of friction composites. PTP maintained both continuous contact and smooth friction braking application of a brake pad. The uniform distribution of Ti on the wear track on the disc worn surface depicts the role of PTPs on stabilizing the friction film formation and eventually on the stability of COF.

The present study was conducted on the disc brake systems of urban railway vehicles to investigate the effects of braking temperature on squeal noise. A finite element method-based analytical model was constructed to predict the generation of squeal noise through the analysis of complex eigenvalues. The reliability of the analytical model was confirmed by verification with experimental results obtained from a test vehicle on an urban railway track in Korea. The braking temperature of the brake system was applied to the analytical model to analyze the effects of braking temperature on squeal noise. This article proposes a brake pad shape to reduce the impact of squeal noise caused by nonuniform contact between the brake disc and the brake pad due to braking temperature. The results from the present study can be used to reduce squeal noise further. [ABSTRACT FROM AUTHOR]

The use of composite materials in brake pads is becoming increasingly popular due to their high-performance characteristics, including good thermal stability, high wear resistance, and low noise generation. However, the development of new composite materials that offer even better performance is still an ongoing research area. In this study, the composite was made by hand layup method using epoxy resin as matrix material, with rice husk, Al2O3, and Fe2O3 as reinforcing materials. The composition of the composites was varied by changing the percentage of the reinforcement materials. The composites were then subjected to several characterization tests, including density, hardness, flexural strength, thermal analysis, Scanning Electron Microscopy (SEM), TGA/DSC, and wear testing. The test results showed that additional reinforcement materials to the epoxy resin matrix improved the mechanical properties of the composites. Overall, the study demonstrates that a hand layup method is a viable approach for preparing brake pad composite materials and that the addition of rice husk, Al2O3, and Fe2O3 can improve the mechanical properties of the composites. The best properties produced in this research were found in one of the specimens which used epoxy, rice husk, Al2O3, and Fe2O3 with a composition of 50 wt.%, 20 wt.%, 15 wt.%, and 15 wt.%. However, the addition of rice husk also provides wear resistance and thermal stability. This study contributes to the Sustainable Development Goals (SDGs) by advancing innovation, promoting sustainability, and reducing emissions in automotive industry applications. [ABSTRACT FROM AUTHOR]

Automobile sector is an important industry that has a crucial role in balancing the world economy. One of the key research area that every researchers concentrate is on the safety of the passengers. Breaking is a crucial portion of automobile, it plays a significant role in safeguarding passengers. For effective braking system, thermal stability during the braking process is necessary. This thermal stability can be achieved only with the proper heat removal from the brake rotor disc and brake pads, where frictional effects are more. In the present proposed work, a novel semi-empirical model for brake design has been discussed and the temperature distributions in an isotropic and orthotropic type brake rotor are presented. This review will help the research fraternity to understand the thermal deformation, which is affected by material and braking mode. [ABSTRACT FROM AUTHOR]

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]

Biomass fibers are promising materials for applications in modern vehicles. They have great economic and ecological significance, as well as a great potential in the fabrication of composite materials due to the relatively high level of strength and rigidity, low density, availability, recyclability, and biodegradability. In this context, the focus is on the development of automotive brake pad materials from sustainable sources. This work refers to the investigation of the behavior of composite materials made of biomass fibers, phenolic resin, graphite and aluminum oxide. These materials are intended to be used for brake pads on automobiles with moderate efficiency. For this purpose, three recipes of composite materials with different percentages of coconut fiber and wood powder were developed in laboratory. The physical and mechanical as well as functional properties of these composite materials with varying amounts of biomass fibers are examined in this paper. The best performances in this terms was obtained for the composite material containing the highest amount of wood powder and the lowest amount of coconut fiber. [ABSTRACT FROM AUTHOR]

The wear debris from conventional brake pads is a growing source of environmental contamination that often leads to life-threatening diseases for human beings. Though the emerging organic brake pads show potential to serve as an eco-friendly alternative, their mechanical and tribological properties are not adequate to withstand the demands of high-wear resistance of a functioning braking system under regular use. Metal matrix composites have served as an optimal solution with minimal environmental pollution and appreciable physical properties. Owing to the popularity of aluminium metal matrix composites, the present study is based on the fabrication and characterization of SiC-reinforced LM6 alloy through stir casting methodologies for evaluating its worthiness in application as a brake pad material. Microstructural, compositional, and phase characterizations were executed through optical micrography, X-ray diffraction, and energy-dispersive X-ray spectroscopy analysis. Although mechanical properties were evaluated through surface hardness investigation, parallel thermal properties were estimated through thermal conductivity evaluation. Finally, the execution of tribological analysis and precise microstructural observations of wear track at ambient and elevated temperatures helped in establishing the datum that the fabricated metal matrix composite (MMC) is a reliable brake pad material alternative. [ABSTRACT FROM AUTHOR]

The use of composite materials in brake pads is becoming increasingly popular due to their high-performance characteristics, including good thermal stability, high wear resistance, and low noise generation. However, the development of new composite materials that offer even better performance is still an ongoing research area. In this study, the composite was made by hand layup method using epoxy resin as matrix material, with rice husk, Al2O3, and Fe2O3 as reinforcing materials. The composition of the composites was varied by changing the percentage of the reinforcement materials. The composites were then subjected to several characterization tests, including density, hardness, flexural strength, thermal analysis, Scanning Electron Microscopy (SEM), TGA/DSC, and wear testing. The test results showed that additional reinforcement materials to the epoxy resin matrix improved the mechanical properties of the composites. Overall, the study demonstrates that a hand layup method is a viable approach for preparing brake pad composite materials and that the addition of rice husk, Al2O3, and Fe2O3 can improve the mechanical properties of the composites. The best properties produced in this research were found in one of the specimens which used epoxy, rice husk, Al2O3, and Fe2O3 with a composition of 50 wt.%, 20 wt.%, 15 wt.%, and 15 wt.%. However, the addition of rice husk also provides wear resistance and thermal stability. This study contributes to the Sustainable Development Goals (SDGs) by advancing innovation, promoting sustainability, and reducing emissions in automotive industry applications.