Wear behaviour of organic asbestos based and bronze based powder metal brake linings

Bronze based brake linings, were produced by powder metallurgy technique and their wear behaviour was investigated and compared to that of asbestos ones. Bronze powders were compacted under 350, 500 and 600 MPa pressures and sintered at 810 °C in ammonia atmosphere for 75 min. For the same friction distance, it was determined that temperature increase in the bronze based brake linings was lower than that of asbestos based ones. However, higher wear rate was observed in the bronze based brake linings. Moreover, thermal conductivity was decreased with high porosity level with low densities. Although, friction coefficient remained the same during breaking, an increase in wear resistance was observed.     

改性酚醛树脂陶瓷摩擦材料的摩擦磨损性能

以普通酚醛树脂、硼改性酚醛树脂、三聚氰胺改性酚醛树脂为黏结剂,以陶瓷纤维为增强纤维,制备了3种酚醛树脂陶瓷摩擦材料。对其冲击韧性和硬度进行实验测试,采用摩擦磨损试验机考察其摩擦磨损性能,采用扫描电子显微镜(SEM)和X射线能谱仪分析其磨损表面形貌及其成分,并探讨其磨损机制。结果表明:硼改性酚醛树脂黏结剂能够提高摩擦材料的硬度,三聚氰胺改性酚醛树脂黏结剂能够提高摩擦材料的冲击韧性,降低摩擦材料硬度;在摩擦过程中三聚氰胺改性酚醛树脂在高温下炭化,在摩擦材料表面形成一层致密的摩擦层,摩擦层的存在使摩擦材料的摩擦因数相对比较稳定,降低了摩擦材料的磨损率。     

C/C刹车盘快速致密化工艺及其性能

为了缩短C/C刹车盘制备周期并提高其性能,介绍了一种制备C/C飞机刹车盘的快速致密化工艺,即采用天然气与丙烷气的混合气体为炭源气体的等温压差CVI法。与常规致密化工艺（丙烯气为炭源气体的等温压差CVI法）相比,C/C刹车盘的CVI(Chemical vapor infiltration) 时间缩短了一半,其导热性能提高5%以上,拉伸、压缩、弯曲与剪切性能提高10%以上,摩擦磨损性能提高20%以上。      

汽车刹车装置摩擦噪声的试验研究

本文对刹车时发出的尖叫摩擦噪声的机理进行了研究。通过对不同工况下摩擦噪声及振动的测量和频谱分析，以及对刹车装置动力学模型的分析与研究表明：尖叫摩擦噪声是由摩擦引发的高频自激振动所致。同时还探讨了这种噪声产生的原因及不同工作条件对其影响的规律。     

多维复合增强汽车摩擦材料

以玻璃纤维、 铜纤维、 矿物纤维、 芳纶纤维、 纳米钛酸钾晶须和片状蛭石等制备多维复合增强非石棉有机汽车摩擦材料, 构成具有“微米和纳米”尺度、 “一维（纤维）和二维（片状）”形态、 “无机和有机”材质的多维复合增强体系。基于材料的力学和摩擦磨损性能测试结果, 通过回归模型分析对复合体系配方进行了优化。通过材料的内部结构和摩擦面的形貌观察, 分析了多维复合增强体系提高材料力学和摩擦磨损性能的内在机制。结果表明, 通过优化配方, 各增强相之间表现出良好的混合和协同效应, 优化多维复合增强汽车摩擦材料的冲击强度为0.54J/cm2、 总磨损率为1.35×10-7cm3/(N·m)、 摩擦系数的变异系数为5.86%。      

列车制动摩擦材料研究进展

简单概述了各类列车制动摩擦材料的发展历史及现状;阐述了它们各自的性能和特点,并据此分析了它们的适用条件与范围。介绍了高速列车制动元件及其材质优化组合与工艺技术的发展趋势     

Performance evaluation of brake pads developed using two different manufacturing methods

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

制动工况参数对制动盘摩擦温度场分布的影响

车用盘式制动器是车辆中的重要零件。在紧急制动过程中,制动压力、整车参数以及轮胎与路面间附着系数之间的关系对制动器摩擦温度场分布有重要的影响。通过有限元仿真,探讨不同制动工况参数对瞬时温度场分布的影响。结果表明：如果忽略制动过程中摩擦热流强度的变化,会给温度场模拟带来较大的偏差。制动初始动能和摩擦力增长过程是影响盘表面温度场的关键因素。     

基于铝热反应Cu-Fe二元合金的微观组织与摩擦性能研究EI北大核心CSCD

基于铝热法制备含2%(质量分数)Al的Cu-Fe合金,采用XRD,SEM,EDS和EBSD技术对Cu-Fe合金的相结构、微观组织进行表征,同时采用HVS-1000A维氏硬度仪和CFT-1材料表面性能测试仪测试Cu-Fe合金的硬度及抗磨损性能。结果表明:利用铝热反应可高效地制备Cu-Fe合金,成分可控,组织致密无夹杂,其中Fe相均匀地分布在Cu基体中,Cu和Fe的相界面结合良好;Fe相的硬度为322.2HV,基体Cu相的硬度为169.3HV,Cu-Fe合金的电导率为40.8 MS/m。铝热法制备的Cu-Fe合金具有较低的摩擦因数,平均摩擦因数为0.124,磨损率为2.17×10^(-3) mm 3·N^(-1)·m^(-1)。     

减少恶性交通事故 汽车制动器“热衰退”现象应予重视

文章从汽车制动器“热衰退”引发的事故入手,分析“热衰退”形成的机理,提出通过采用新型摩擦材料、提升摩擦材料标准水平及社会多方综合治理等措施减少“热衰退”现象。     

Al_2O_3颗粒镀铜对铜基粉末冶金摩擦材料Al_2O_3-Fe-Sn-C/Cu摩擦磨损性能的影响

通过对陶瓷摩擦组元的表面进行化学镀铜来改善铜基粉末冶金摩擦材料中陶瓷相与基体间的结合效果,从而提高材料摩擦磨损性能。分别采用镀铜Al2O3颗粒和未镀铜Al2O3颗粒与铜粉和铁粉等经混合、压制、加压烧结制备Al2O3-Fe-Sn-C/Cu摩擦磨损试样。测试并分析了摩擦材料的微观结构、力学性能及摩擦磨损性能。结果表明:摩擦组元镀铜可使硬质颗粒与铜基体结合紧密;摩擦材料的布氏硬度增加了12%,弹性模量提高了约7%,摩擦系数提高了5%~10%,线磨损量降低了20%~50%;表面镀铜后的Al2O3颗粒不易脱落,摩擦系数稳定性提高了13%~23%。研究结果表明,摩擦组元表面镀铜可提高材料的综合性能。     

三维网络SiC对铝合金干摩擦磨损性能的影响

用销-盘式高温摩擦磨损实验机研究了LF3铝合金及三维网络SiC(体积分数分别为10％、20％、30％)增强LF3铝基复合材料的干摩擦磨损性能，测量了复合材料及基体合金在室温和高温(25-300℃)条件下的摩擦系数和磨损率，用扫描电镜(SEM)观察其磨损表面，研究了三维网络SiC对铝合金磨损机制的影响．结果表明：复合材料的干摩擦磨损性能远优于基体合金(LF3)，而且随着温度的升高，复合材料的抗磨损性能明显提高．三维网络SiC在磨损表面形成硬的微凸体起承载作用，同时其独特的结构制约基体合金的塑性变形和高温软化，并保护在磨损表面形成的氧化膜．在相同实验条件下，复合材料的摩擦系数、磨损率随着增强体的体积分数的增加而降低．复合材料的摩擦系数在滑行过程中的稳定性明显高于基体合金．     

Linear eigenvalue analysis of the disc‐brake squeal problem

This paper presents a numerical method to calculate the unstable frequencies of a car disc brake and suggests a suitable analysis procedure. The stationary components of the disc brake are modelled using finite elements and the disc as a thin plate. The separate treatments of the stationary components and the rotating disc facilitate the modelling of the disc brake squeal as a moving load problem. Some uncertain system parameters of the stationary components and the disc are tuned to fit experimental results. A linear, complex‐valued, asymmetric eigenvalue formulation is derived for the friction‐induced vibration of the disc brake. Predicted unstable frequencies are compared with experimentally established squeal frequencies of a real car disc brake. Copyright © 2004 John Wiley & Sons, Ltd.     

Wear resistance of plasma coatings for a constant work of friction

We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of fatigue processes on the surfaces. The comparative characteristics of coatings are presented. __________ Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007.     

铜-塑自润滑复合材料的设计和性能

提出了一种新的铜--塑自润滑复合材料的设计方法，导出了其极限承载力与摩擦系数的关系．在此设计理论基础上研制出新型铜一塑复合材料NTS-100．自润滑复合材料承受的弹性模量越小、接触应力越大，其承载力越大；接触面的剪切强度越小，摩擦系数越小．铜--塑自润滑纳米滑块的承载能力高、摩擦系数小．填充纳米A1203在保持低摩擦系数同时，提高承载力，抑制聚四氟乙烯(PTFE)塑料的蠕变，减少实际接触面积，降低时效摩擦系数．     

Influence of friction stir processing parameters on surface modified 90Cu-10Ni composites

Friction Stir Processing (FSP) has emerged as a distinctive and pioneering solid state technique to produce surface composites. The objective of the present research is to produce reinforced 90/10 Copper–Nickel surface composites with different carbide-based ceramic particles through FSP and study the relationship of its dynamic parameters including tool rotational speed, tool traverse speed, and width of the groove over the surface behavior. Responses such as sliding wear, microhardness, and surface modified area in the friction stir processed region are modeled using polynomial, nonlinear, multiple regression based on the central composite design of experiment. Analysis of the developed models showed that the FSP parameters; traverse speed, rotational speed, and groove width have significant influence on both the sliding wear and microhardness of developed surface composite. And furthermore, tool rotational speed and tool traverse speed, simultaneously control dispersion of reinforcement in the surface. To validate the abovementioned noteworthy results and to study the microstructural aspects, selected specimens were carried over metallurgical analysis and the obtained results were put forward in detail in this paper.     

汽车制动钳滑移阻力检测系统研制

依据国家汽车制动系统行业相关标准研制汽车制动钳滑移阻力检测系统.以行业标准和企业测试要求为依据,制定活塞滑动阻力测试方案,引入高精度数据采集、伺服精密加载控制、测量系统分析等技术,设计基于伺服运动控制的精密加载机构的测量装置、采用真空泵用来对系统抽真空实现系统自动可调节的真空源,利用气液增压器、电气比例阀来满足对气液源...     

汽车树脂基刹车材料的摩擦机理及其对刹车材料的要求

介绍了汽车刹车材料的摩擦磨损理论,在此基础上对树脂基刹车材料及其原材料的要求做了综述性介绍.指出:①对酚醛树脂进行增韧和耐热改性是刹车材料用酚醛树脂的重要研究方向;②混杂纤维是增强纤维研究的重要内容;③填料的作用不可忽视.最后提出高性价比的环保型刹车材料是刹车材料的研究方向.     

C/C复合材料飞机刹车盘的结构与性能

采用企业、行业及国家相关标准的试验方法，对超码复合材料公司，英国Dunlop公司，法国CarbonIn-dusty公司，美国B．F．Goodrich、ALS公司等生产的9种C／C复合材料飞机刹车盘的物理、力学、热学、摩擦磨损的性能特征，以及中南大学生产的C／C复合材料刹车盘的有关性能，进行了对比分析。结果表明，选择适宜的炭纤维预制体结构，控制热解炭基体微观结构为光学粗糙层结构，合理的热处理温度是获得高性能炭刹车盘材料的关键。我国拥有自主知识产权研发的大型民机炭刹车盘在高摩擦特性方面获得了重大突破，已用于波音757—200型飞机，实现了国内C／C复合材料具有里程碑意义的第四个重大突破。     

AZ91及AZ91-Y合金复合干摩擦性能的对比

为了探究AZ91镁合金的复合干摩擦行为,以未淬火45钢为摩擦副,在不同载荷下(100,200,300 N),开展AZ91及Y含量为1.0%(质量分数)合金的复合干摩擦实验。采用OM,XRD,SEM等观察合金的磨损形貌并分析磨损机理。结果表明:增加法向载荷,两试样复合磨损率线性增加但摩擦因数却逐渐减小;Al 2Y硬质颗粒可细化晶粒、弱化相界面开裂倾向以提高AZ91-Y合金耐磨性。100,300 N法向载荷下,AZ91-Y合金主要磨损机制分别为磨粒磨损和剥离磨损,与基体(AZ91)一致,其磨损率分别降低了21.7%和5.9%。