Sustainable Biocomposites Materials for Automotive Brake Pad Application:An Overview

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.

Application Research on Self-healing Technology with Microcapsules for Automobile Brake Pad

In order to improve the performance of non-asbestos composite auto brake pads that are composed of matrix resin, reinforced material and fillers, a novel method with new technology of self-heal microcapsules was proposed. Nano reinforced fillers＇ effects were also considered in the experiment project. Five recipe designs for new composite auto brake pads were carried out and cor-responding samples were prepared as well. The friction coefficient and wearing properties at certain temperature, impact intensity and hardness were comparatively studied. Investigations indicate that properties of such composite auto brake pads meet the requirements of the national standards while microcapsule＇s weight content varies from 5.5wt%-1.09wt% of matrix resin and microcapsule＇s loca-tion varies in the pads. Nano reinforced fillers have the effects of increasing composites＇ impact in-tensity and hardness. Application of self-healing microcapsules in auto brake pads is feasible.

Reliability Evaluation of CRH_(3C) Brake Pads Based on Bayes Method

In the reliability life evaluation of CRH_(3C) brake pads,the evaluation model of reliability life is put forward based on the Bayes method in the small sample. The correctness of evaluation model is validated by comparing and analyzing with the evaluation results based on Bootstrap simulation. Also by comparing the result with the semi-empirical method,the life evaluation results of the brake pads which are based on the Bayes method are more actual. The results which are based on the Bayes method can provide the theoretical basis and guidance for the repair and replacement of brake pads.

Rock Magnetic Characterization of Fine Particles from Car Engines, Brake Pads and Tobacco: An Environmental Pilot Study on Oahu, Hawaii, USA

Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Hawaii, of particulate matter (PM) PM = 60, PM = 10, and PM = 2.5. In order to do a rock magnetic characterization we have performed low field susceptibility vs. temperature [k-T] experiments to determine the Curie points of small particles collected from exhaust pipes, as well as from brake pads of four different types of car engines using gasoline octane ratings of 87, 89, and 92. The Curie point determinations are very well defined and range from 292°C through 393°C and up to 660°C. In addition, we have conducted magnetic granulometry experiments on raw tobacco, burnt tobacco ashes, as well as on automotive engine exhaust, and brake pads in question. The results of the experiments show ferro and ferrimagnetic hysteresis loops with magnetic grain sizes ranging from superparamagnetic-multidomain [SP-MD], multidomain [MD] and pseudo-single domain [PSD] shown on the modified Day et al., diagram of Dunlop (2002). Thus far, the results we have obtained from this pilot study are in agreement with other studies conducted from cigarette ashes from Bulgaria. Our results could be correlated to the traffic-related PM in Rome, Italy where the SP fraction mainly occurs as coating of MD particles originated by localized stress in the oxidized outer shell surrounding the un-oxidized core of magnetite-like grains. All these magnetic particles have been reported to be very harmful to our human bodies (i.e. brain, lungs, heart, liver etc.).

CNN-LSTM based on attention mechanism for brake pad remaining life prediction

In order to predict the remaining service life of brake pads accurately and efficiently,and to achieve intelligent warning,this paper proposes a CNN-LSTM brake pad remaining life prediction model based on an attention mechanism.The model constructs a non-linear relationship between brake pad features such as brake temperature,brake oil pressure and brake speed and brake pad wear data through convolutional neural network(CNN)and long and short term memory network(LSTM),as well as capturing the time dependence that exists in the brake pad wear sequence.The attention mechanism is also introduced to assign different weight values to the features output from multiple historical moments,highlighting the features with high saliency and avoiding the influence of invalid features,so as to improve the prediction effect of the remaining brake pad life.The results show that the proposed CNN-LSTM-Attention model can effectively predict the remaining life of brake pads,with the mean absolute error MAE value of 0.0048,root mean square error RMSE value of 0.0059 and coefficient of determination R2 value of 0.9636;and compared with the BP model,CNN model,LSTM model and CNN-LSTM model,the coefficient of determination R2 values are closest to 1,with an improvement of 8.26%,5.25%,3.99%and 1.85%respectively,enabling more effective monitoring and intelligent warning of the remaining brake pad life.

Experimental investigations on wear properties of Palm kernel reinforced composites for brake pad applications

The use of asbestos material is being avoided to manufacture the brake pads as it is harmful and toxic in nature. Further it leads to various health issues like asbestosis, mesothelioma and lung cancers. These brake pads can be replaced by natural fibers like Palm kernel (0-50%), Nile roses (0-15%) and Wheat (0-10%) with additives like aluminum oxide (5%-20%) and graphite powder (10%-35%). Phenolic resin of 35% is utilized as a binder. Particulated Nile roses are used to increase the friction coefficient and wheat powder is used to reduce the wear rate. Aluminum oxide and graphite are abrasive in nature. This helps to make brake pads with high friction co-efficient and less wear rate with low noise pollution. The wear of the proposed composites have been investigated at different speeds. Various tests like wear on pin-ondisc apparatus, hardness on the Rockwell hardness apparatus and oil absorption test have been conducted. Phenolic resin produces good bonding nature to fiber. Thus, Fibers found to have performed palatably among all commercial brake pads. The objective of the research indicates that Palm kernal shell could be a conceivable alternative for asbestos in friction coating materials.

Mechanical Properties of Powder Based Steel used as Backing Plate in Heavy Duty Brake Pad Manufacturing

The aims of the present study is to develop a powder based steel used as backing plate for heavy duty brake pad applications. Three powder based back plate steel compositions namely B1 (C- 0.3, Cu – 1.5, P -0.3, Fe – 97.9), B2 (C- 0.1, Cu – 2.5, SiC-1, Fe – 96.4) and B3(C- 0.5, Cu – 2.5, SiC-1, Fe – 96.0) were prepared using a hot powder preform forging technique. The forged samples are of (25× 50×10 mm3) dimensions. These samples were hot rolled and annealed to relieve the residual stresses. These samples were characterized in terms of microstructure, porosity content/densification, hardness and tensile properties. Densification as high near to theoretical density has been realized. Hot powder preform forging using closed die showed better densification. Rolled and annealed microstructure showed lesser porosity content than the forged one. Phosphorous causes hardening of ferrite in solid solution with iron. Compositions B1, showed reasonable elongation and it improved further on annealing. It was observed in this present investigation that, the addition, such as SiC and Cu caused increase in strength. Steel developed in the investigation are used as powder based backing plate in Manufacturing of iron based brake pads used in heavy duty applications.

Weibull approach to brake pad wear analysis in the Nigerian market

In this study,we evaluated the wear properties of four brands of brake pad available in the Nigerian market.In particular,we assessed the tribo performance and service life of the brake pads.We purchased four commercial brands of brake pads used in light duty cars and coded them as AU,SN,TY and SM,respectively.A small piece of the brake pad lining materials was carefully chiseled from the back plates to obtain samples for the experiments.We conducted Brinell hardness tests using a tensometer and a pin-on-disc test rig to determine the coefficient of friction and the wear characteristics of the materials.We then correlated the wear on each set of brake pads with the running time and used Weibull’s equation to determine average service life.Sample TY exhibited the highest hardness value(29.09)and sample SN the lowest(10.05).The determined coefficients of friction ranged between 0.3-0.36,with sample AU exhibiting the lowest value and sample SM the highest.Sample SN showed the lowest wear rate of 3.53×10^(9) g/min,while the wear rates of samples TY,AU,and SM were 5.64×10^(8),8.19×10^(9),and 2.10×10^(8) g/min,respectively.The relative service life of samples SN,TY,and AU were similar,with average values of 2778.09,2725.41,and 2717.34 min,respectively,and SM had a relatively low service life(2017.82 min).We conclude that the overall performances of Nigerian brake pads do not meet all the specifications for friction materials used in road vehicle brake linings and pads.

Role of titanium carbide and alumina on the friction increment for Cu-based metallic brake pads under different initial braking speeds

To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produced and tested using a scale dynamometer under various initial braking speeds(IBS).The results showed that at IBS lower than 250 km/h,both TiC and Al_(2)O_(3) particles acted as hard points and exhibited similar friction-increasing behavior,where the increase in friction was not only enhanced as IBS increased,but also enhanced by increasing the volume fraction of the abrasives.However,at higher IBS,the friction increase was limited by the bonding behavior between the matrix and abrasives.Under these conditions,the composite containing TiC showed a better friction-increasing effect and wear resistance than the composite containing Al_(2)O_(3) because of its superior particle-matrix bonding and coefficient of thermal expansion(CTE)compatibility.Because of the poor interface bonding between the matrix and Al_(2)O_(3),a transition phenomenon exists in the Al_(2)O_(3)-reinforced composite,in which the friction-increasing effect diminished when IBS exceeded a certain value.

列车刹车闸片冶金材料成分配比优化研究

为了促进我国列车刹车闸片粉末冶金材料的发展,研究分析了不同增强组元对粉末冶金材料制备的摩擦材料性能影响。研究分析的2种增强组元分别是羰基铁粉和磷铁粉,粉末冶金材料的基体为超细铜粉,润滑组元为镀铜石墨,摩擦组元为铬铁粉。结果显示,时速低于275 km/h时,磷铁粉材料的摩擦系数更高,时速高于275 km/h时,羰基铁粉的摩擦系数更高,时速为350 km/h时,羰基铁粉材料磨损量为0.625 mg/kJ,磷铁粉材料磨损量为1.634 mg/kJ,研究还探讨了磷铁粉及羰基铁粉对列车刹车材料摩擦性能的影响,对我国粉末冶金材料、制备列车刹车闸片的发展具有指导意义。

250 km/h动车组用闸片制动摩擦及噪声特性

利用1∶1台架试验探究了250 km/h城际动车组闸片-盘紧急制动过程中的摩擦及噪声特性。结果表明当速度为50~250 km/h时,摩擦系数受制动速度增长影响较小,而制动压力的增加仅在250 km/h时诱导摩擦系数下降,表明该型闸片具有优异的摩擦系数稳定性。对于噪声特征,5000 Hz以下的噪声占主导地位,而更高频噪声只出现在某些特定的频率段。制动速度的增加会增加制动初期的噪声强度和频率范围,而压力提高则带来相反的抑制作用。高制动压力会促使制动后期高频啸叫的产生。因此,在制动时采用先高压力后低压力的变压力制动方式可能是降低高频制动噪声的方法。

刹车片颗粒及其主要成分硫化锑呼吸暴露对小鼠健康危害研究

目的研究刹车制动来源颗粒物对机体的潜在危害。方法研磨刹车片颗粒、硫化锑颗粒,小鼠通过气管灌注暴露1个月后,观察肺、心脏、肝等内脏器官病理改变,同时用流式细胞术分析外周血巨噬细胞和自然调节T淋巴细胞(regulatory T cell,Treg)的变化。结果刹车片颗粒及硫化锑颗粒暴露小鼠肺泡壁外源物质沉积,血管周围出现明显的炎症细胞浸润并随着暴露浓度的增加而加重,同时可出现心脏血管炎症和微血栓以及肝细胞肿胀等病理改变;Treg细胞减少,硫化锑组和低剂量刹车片组巨噬细胞增加,同时M2型巨噬细胞比例下调。结论刹车片颗粒及其成分硫化锑颗粒暴露对小鼠肺、心脏、肝等脏器具有不同程度的毒性作用,并对免疫系统造成了影响,提示刹车来源的空气污染存在潜在健康危害。

合成摩擦材料在轨道交通领域的应用与发展

合成摩擦材料以其重量轻、摩擦系数稳定、性能可调节性强等优点,成为轨道交通列车制动装置中的关键材料,主要产品应用于制动的合成闸片、合成闸瓦和用于踏面清扫及修形的研磨子。综合概述了合成摩擦材料在我国轨道交通领域的发展历程,详细介绍了3种产品的物理力学性能和摩擦性能特点,并就合成摩擦材料在铁路机车、城市轨道交通列车、动车组列车等轨道交通上的应用实例和发展情况做了分析。基于列车行驶和制动的复杂工况,对合成摩擦材料在使用过程中常见的金属镶嵌、裂纹、异常磨耗等问题进行成因剖析并提出解决策略。面对轨道交通“提速、重载、轻量化、安全”的发展趋势,提出合成摩擦材料在深化基础理论研究、更高速度等级应用及摩擦副匹配关系等方向的发展需求,为我国在合成摩擦材料的研究及应用提供参考和思路。

Transient Temperature Field Analysis of Brake in Nonaxisymmetric Three-dimensional Model

The disk-pad brake used in automobile is divided i nt o two parts: the disk, geometrically axisymmetric, and the pad, of which the geo metry is three-dimensional. In the course of braking, all parameters of the pro cesses (velocity, load, temperature, physicomechanical and tribological characte ristics of materials of the couple, and conditions of contacts) vary with the ti me. Considerable evidence has show that the contact temperature is an integral f actor reflecting the specific power friction influence at the combined effect of load, speed, friction coefficient, thermo physical and durability properties of materials of a frictional couple. Furthermore, the physic mechanical state of t he interface of the disk and pads is determined not only by the contact temperat ure but also by the nonstationary temperature field. Using the two-dimensional model for thermal analysis implies that the contact conditions and frictiona l heat flux transfer are independent of θ. This may lead to false thermal elast ic distortions and unrealistic contact conditions. An analytical model is presen ted in this paper for the determination of contact temperature distribution on t he working surface of a brake. To consider the effects of the moving heat source (the pad) with relative sliding speed variation, a transient finite element tec hnique is used to characterize the temperature fields of the solid rotor with ap propriate thermal boundary conditions. And the transient heat conduction problem can be solved as a nominal 3-D transient heat transfer problem with an immovab le heat source. Numerical results shows that the operating characteristics of th e brake exert an essentially influence on the surface temperature distribution a nd the maximal contact temperature. The temperature field presents a noaxisymmet ric characteristic (a function of θ) and proves to be strongly localized and po ssesses a sharp gradient in both axial and radial directions.

时速350km高速列车用铜基闸片材料的摩擦性能

闸片是高速列车制动系统的核心部件,本文设计了350 km·h^(-1)高速列车用铜基闸片材料,对闸片进行了1∶1台架实验考核,重点分析了摩擦膜的性质及闸片的摩擦磨损性能.结果表明,研制闸片不仅具有优异的摩擦系数稳定性和低的磨耗,还具有不伤盘的特点.瞬时摩擦系数和平均摩擦系数均满足TJCL/307—2019标准的要求,摩擦系数稳定性为0.0015,250~380 km·h^(-1)制动速率范围内的摩擦系数热衰退仅0.027,在380 km·h^(-1)下的平均摩擦系数仍维持在0.35,平均磨耗仅0.06 cm^(3)·MJ^(–1).闸片优异的摩擦制动性能归因于形成了高强韧、低转移速率的摩擦膜.利用大粒径摩擦组元作为外部运动障碍钉扎摩擦膜.摩擦膜中的亚微米磨屑作为摩擦膜与对偶盘的啮合点,提供摩擦阻力,以保持高速制动时的摩擦系数.添加的易氧化组元为摩擦膜源源不断提供氧化物,研磨生成的纳米氧化物作为弥散相强化摩擦膜.通过多尺度颗粒的协同增强,实现了摩擦膜的动态稳定化,赋予了闸片优异的摩擦磨损性能.

Development of Iron Based Brake Friction MMC Used for Military Aircraft Application by A New P/M Route

A new P/M route based hot powder pre-form forging process has been evolved to develop high density brake materials for heavy duty applications. Number of iron based MMC’s so developed offer better characteristics for braking applications in comparison to the materials developed through conventional P/M route based on high pressure compaction and pressure sintering. The process so developed in the present investigations is much simpler and easy to adopt by existing P/M industries. Hot powder pre-form forging technique for making heavy duty brake pads offers better opportunity for pore free material with better bonding between various metallic and non-metallic constituents. After conducting an initial characterization such as hardness, density and Pin-on Disc tests, the samples were tested for high energy (32,933kgfm) on Sub-scale dynamometer under Rejected Take Off conditions. The results have also been compared with respect to brake pads employed in heavy duty Military aircraft tested under identical laboratory conditions. The present work indicates that the newly developed materials compare better than the one being currently employed in heavy duty aircraft. The reasons for better performance are improved processing technique and resulting higher levels of density and improved binding of the product.

Development of Iron Based Brake Friction Material by Hot Powder Preform Forging Technique used for Medium to Heavy Duty Applications

A promising friction material, Iron -based friction material, was prepared by powder metallurgy (PM) processing utilizing hot powder preform forging (near net-shape).The preparation of the product and its characterization are presented in this paper. These products are useful in heavy duty Military Aircraft applications such as AN-32. In order to eliminate costly environmental control systems to protect products during their high temperature processing (as is conventionally practiced employing hydrogen gas), the present investigation relies on carbon (mixed in the brake pad formulation) as reducing agent and high temperature oxidation resistant glassy coating (separately developed) applied over the product’s surface after cold compacting. After conducting an initial characterization such as hardness, density and Pin-on Disc tests, the samples were tested in sub-scale dynamometer under Rejected Take Off conditions. It was observed that the obtained density in the present investigation is higher than the reported density obtained by sintering route, and wear is on the lower side of the range as per the Aeronautical Standards. Optical metallography was used to investigate the microstructure of friction, interface and backing layer. It was observed that the distribution of ingredients in matrix was homogeneous. The results also indicate that the coefficient of friction is more stable, and wear is lower with respect to temperature rise. .

基于卷积神经网络的盘式刹车片表面缺陷检测

汽车刹车片质量关系车辆驾驶安全,目前汽车刹车片表面缺陷主要采用人工抽检和机器视觉检测的方法,人工抽检存在效率低、易出现漏判与误判表面缺陷的问题,机器视觉检测则需要依靠被检测对象的特定特征进行检测。为此,以业界广泛应用的盘式刹车片为研究对象,提出一种改进AlexNet卷积神经网络模型,即AlexNet6_BN模型,对盘式刹车片进行表面缺陷检测。对经典AlexNet卷积神经网络模型中的卷积层进行调整,增加了1层卷积层和1层池化层,调整首层卷积核大小为13×13以提取更为显著的样本特征,并在每层卷积层后用批量标准化代替原来的局部响应归一化以加快网络收敛速度。实验测试表明,改进后的网络模型对刹车片表面缺陷识别的准确率均高于AlexNet、VGG16等经典网络,其检测准确率达到97%。

B_(4)C改性Cu基刹车片配对C/C-SiC的摩擦学行为及机理

Cu基刹车片在高速循环制动过程中存在基体软化和摩擦膜破裂的问题。采用粉末冶金法制备碳化硼(B_(4)C)质量分数为0~6%的Cu基刹车片,并选取C/C-SiC制动盘作为对偶件,研究制动过程中形成的B_(2)O_(3)摩擦膜对摩擦磨损性能的影响,并分析磨损机制。结果表明,通过B_(4)C改性可降低Cu基摩擦材料的密度,w(B4C)为4%和6%时,材料密度显著降低,强度大幅提高,并分别获得最优的抗热衰退性能和最低磨损率。制动过程中B_(4)C氧化形成的B_(2)O_(3)具有类似于MoS_(2)和石墨的层状晶体结构,在滑动界面处容易剪切,从而提高平均摩擦稳定系数并降低磨损率。在B4C表面形成的B_(2)O_(3)与Cu基体结合良好。当B_(4)C质量分数超过4%时,Cu基刹车片的磨损机制从分层磨损为主转变为氧化磨损为主。

铜基粉末冶金摩擦块摩擦磨损特性研究

为了探究铜基粉末冶金闸片块的摩擦磨损特性,在UMT-5摩擦试验机上进行销-盘摩擦试验,研究分析了转速、压力、温度对摩擦磨损性能的影响,并用3D光学显微镜对摩擦表面形貌进行分析。研究表明:摩擦块在235N法向压力时,随着摩擦盘转速的升高和摩擦时间的增加,摩擦块表面逐渐形成稳定的摩擦膜,平均摩擦系数先上升后下降,磨损量先下降后上升,然后再下降;在353N的法向压力下,随着摩擦盘转速的升高和摩擦时间的增加,没有形成稳定的摩擦膜,平均摩擦系数呈增大趋势,磨损量先减小后增大。两种压力下摩擦块的主要磨损形式都从轻微剥落向磨粒磨损转变,最终转变为剥层磨损和黏着磨损。