汽车摩擦材料的研究现状与发展趋势

现代汽车的发展对汽车摩擦材料提出了更高的要求,摩擦材料性能的优劣将直接影响到汽车行驶安全性、稳定性、舒适性。从汽车无石棉摩擦材料种类、配方设计、制备工艺与设备、摩擦材料性能评价与测试方法等方面介绍了现代汽车摩擦材料的研究现状与发展趋势。     

汽车制动摩擦材料研究进展

简述了汽车制动摩擦材料的发展史,对常见汽车制动摩擦材料进行分类并对其性能进行了比较,介绍了现代汽车制动摩擦材料的发展趋势。     

微型汽车离合器摩擦材料的热衰退现象

设计了适合研究树脂基汽车复合摩擦材料摩擦性能的小样试验,进行不同环境温度、不同滑动速度和定载荷下的摩擦试验。并通过扫描电子显微镜的分析手段,结合摩擦学原理分析了摩擦材料的热衰退机理,得出树脂基汽车复合摩擦材料热衰退的实质是树脂的高温热分解所生成的润滑层或气垫层的动力润滑而导致摩擦因数的明显下降,其机理是从典型的磨粒磨损和粘着磨损的干摩擦过渡到具有流体润滑磨粒磨损的润滑摩擦等结论。     

汽车摩擦材料摩擦磨损性能试验的现状与发展

汽车摩擦材料的摩擦磨损性能直接影响车辆行驶的安全性、舒适性和耐久性。工况条件是影响摩擦磨损性能的重要因素。摩擦磨损性能的试验结果将为摩擦材料的配方设计、制造工艺的调整提供依据。因此试验工况的模拟性及测试评价方法的选择显得至关重要。介绍了汽车摩擦材料摩擦磨损性能试验的类型、方法、使用范围及应用现状,对现有不同的试验进行了比较,并对其发展趋势加以总结。     

水润滑条件下制动材料摩擦学性能研究进展

汽车刹车片摩擦因数在雨天或湿润的环境里衰退到非常低的水平是一个很严重的问题,直接威胁到交通安全。但目前国内外关于摩擦材料的试验规范并没有涉及到水润滑条件,相关的研究应越来越受到人们的重视。介绍摩擦材料在水润滑条件下的摩擦性能及相关研究的现状,对比干、湿2种条件下的摩擦机制,表明水作为一种冷却介质和润滑介质,对摩擦材料性能产生了复杂的影响。提出水润滑条件下摩擦材料的研究方向。     

多纤维增强汽车制动器摩擦材料的研制

用芳纶浆粕、玻璃纤维、硅灰石纤维和钛酸钾晶须混杂增强汽车制动器摩擦材料,在XD-MSM定速式摩擦试验机进行摩擦磨损性能实验,并探讨了纤维含量对摩擦磨损性能的影响.实验表明所研制的摩擦材料完全满足汽车制动性能的要求,具有良好的机械性能,热衰退小、恢复性能好.混杂纤维的质量分数为29%时,材料摩擦磨损性能最佳.     

混杂纤维含量对汽车制动摩擦材料性能的影响

研究了不同混杂纤维含量对汽车制动摩擦材料性能的影响.结果表明,随着坡缕石纤维和钢纤维含量的增加,摩擦材料的冲击强度均增加;坡缕石含量的变化对磨损率影响不大,Kevlar含量较高时,混杂纤维摩擦材料200 ℃时磨损率增加,250 ℃和350 ℃时磨损率降低;Kevlar纤维随着其含量的增加,混杂纤维摩擦材料高温摩擦性能(250～350 ℃)有所降低.     

多纤维增强汽车制动器摩擦材料的摩擦磨损特性研究

制备一种多纤维增强汽车制动器摩擦材料。为了解多纤维增强摩擦材料各组分在制动摩擦过程中所起的作用,采用XD-MS定速式摩擦试验机测定所制备的摩擦材料的摩擦磨损性能,通过扫描电镜观测在不同温度下磨损后的表面形貌。结果表明:摩擦材料的摩擦因数比较稳定且在高温时摩擦因数没有显著下降,磨损率也在规定范围内;摩擦材料在低温下主要是磨粒磨损,高温下树脂分解产生热磨损,同时伴随着磨粒磨损和疲劳磨损。     

干式制动片摩擦材料的研制和性能试验

采用MM—1000型摩擦试验机,对自行研制的FM粉末冶金摩擦材料进行模拟试验。研究压力、速度、温度对该材料摩擦学性能的影响,通过多种型号汽车装车试验证实,该材料制动灵,使用寿命长。可用作各种干式制动器摩擦片材料。     

经济型汽车干摩擦式离合器的磨损及影响因素

磨损是经济型汽车干摩擦离合器损坏的主要原因.通过分析经济型汽车干摩擦式离合器在滑动摩擦条件下磨损的基本类型及其影响因素,得出磨粒磨损、粘着磨损和疲劳磨损是其磨损的基本类型,摩擦材料、温度和滑动速度是磨损的主要影响因素;通过分析经济型汽车干摩擦离合器磨损过程三个阶段的磨损类型和磨损量,得出缩短磨合磨损阶段、延长稳定磨损阶段和推迟剧烈磨损阶段可以提高离合器的使用寿命;通过摩擦学性能试验和耐磨损性试验,得出提高离合器摩擦副的材料性能、降低离合器摩擦副的表面粗糙度和改善离合器工作条件(温度、滑动速度和工作载荷)等措施,有助于增强干摩擦式离合器的摩擦性能和耐磨性,从而降低经济型汽车干摩擦式离合器的磨损.     

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.     

机械自动化技术在摩擦材料行业的应用研究

汽车制动摩擦材料是汽车制动系统中至关重要的部件,起到保障行车安全的作用。摩擦材料的生产方式从简单的手工操作及批次生产逐步发展到机械控制自动化和流水线生产。机械自动化不仅提高了劳动生产率,减少了粉尘污染,而且改进了生产技术及产品质量控制,推动了汽车制动行业的发展。通过介绍机械自动化技术在车用摩擦片生产过程中的应用,来解读先进的摩擦片生产过程。     

On the role of copper in brake friction materials

Copper is a major ingredient in friction materials used for automotive braking. The purpose of this study was to find out how copper contributes to good brake performance properties in addition to providing good thermal conductivity. Microstructural investigations of copper chips at the surfaces of brake pads revealed a zone of severe plastic deformation which provides high hardness, but there is also evidence of recrystallized copper nano-particles which are incorporated into friction layers as soft ingredient once detached from the pad surface. Thus copper seems to play a dual role, firstly as reinforcing element of the brake pad providing primary contact sites, and secondly as solid lubricant by contributing to the formation of a layer of granular material providing velocity accommodation between the rotating disc and fixed pad. Confirmation for this hypothesis was obtained by modelling contact sites on the nanometre scale with the method of movable cellular automata. Results show both, the similarity of steel fibres and copper macro-particles in respect to providing primary contact sites, as well as similar sliding behaviours of friction layers containing either copper or graphite as soft inclusions. Furthermore, it is shown that not only material properties, but also the concentration of solid lubricant particles in the friction layers, determine conditions for friction force stabilization and smooth sliding behaviour.     

Neural network prediction of disc brake performance

An automotive brake's performance results from the complex interrelated phenomena occurring at the contact of the friction pair. These complex braking phenomena are mostly affected by the tribochemical properties of the friction material's ingredients, the brake disc properties, and the brake's operating regimes. In this paper, the synergistic effects of the friction material's properties, defined by its composition and manufacturing conditions, and the brake's operating regimes on the disc brake factor C variation have been modelled by means of artificial neural networks. The influences of 26 input parameters, determined by the friction material composition (18 ingredients), its manufacturing conditions (5 parameters), and the brake's operating regimes (3 parameters) on the brake factor C variation, have been predicted. The neural model of the disc brake cold performance has been developed by training 18 different neural network architectures with the five different learning algorithms. The optimal neural model of disc brake operation has been shown to be valid for predicting the brake factor C variation of the cold disc brake over a wide range of brake's operating regimes and for different types of friction material.     

半金属基提速客车盘形制动闸片摩擦特性的研究

介绍了一种适用于制造提速客车（v＝160km／h）盘形制动问片的半金属基摩擦材料的摩擦磨损特性。试验表明,研制的A配方半金属摩擦材料具有稳定的摩擦系数和较好的耐磨性及其抗热衰退性。实物惯性台某试验结果表明,研制的A配方问片具有较高的摩擦系数,制动距离较短,制动性能稳定,完全能满足提速客车运行的制动要求。     

Tribological study of gray cast iron with automotive brake linings: The effect of rotor microstructure

Experimental studies of friction characteristics were conducted using gray cast iron and automotive brake linings. The gray iron samples were manufactured to have different microstructures by changing the carbon equivalent and cooling speeds of melts and two different types of non-commercial brake linings (non-steel and steel-containing linings) were used as a counter material. Friction tests were performed on a pad-on-disk type tribotester and particular emphases were given to the effect of graphite flakes and ferrite in the gray iron disks on fade phenomena and the level of the coefficient of friction. Results showed that the coefficient of friction increased with the amount of graphite flakes on the gray iron and the effect was more pronounced in the case of using steel-containing linings. The amount of ferrite phase on the disk surface showed little influence on the coefficient of friction. Fade resistance of non-steel linings was improved with the increase of graphite flakes on the disk surface and steel-containing linings showed good fade resistance regardless of graphite contents in the gray iron disks.     

Experimental investigation and neural network prediction of brakes and clutch material frictional behaviour considering the sliding acceleration influence

The developers of innovative automotive active systems have recently stimulated new interest toward the analysis of the frictional behaviour of brake and clutch facings.This paper presents the experimental results acquired with a laboratory setup on brake and clutch facing samples in sliding motion for different operating conditions. An artificial neural network has been used to obtain a comprehensive view of the influence of the main sliding parameters.The study has also taken into account the not weak influence of the sliding acceleration to improve the friction coefficient prediction during transient operations of these dry friction based devices.     

Wear performance and wear debris of semimetallic automotive brake materials

Wear performance of automotive brake material is addressed and debris collected after brake dynamometer test and after ball-milling of identical semimetallic friction lining is characterized using a combination of analytical techniques. The differences between dynamometer wear debris and ball-milled samples are demonstrated. Wear debris is typified by the presence of numerous nanoparticles formed during wear process. Their chemistry resembles the chemistry of friction layer described previously. Contradicting findings by different research groups addressing automotive wear particulates are discussed and further refinement of analytical and testing techniques as well as their combination is suggested.     

汽车液压制动软管的寿命优化

液压制动软管因有可靠的柔韧性、耐压性和耐高温性而被广泛应用于机械和化工行业,在汽车、火车、飞机以及高铁动车组列车中都得到广泛应用,而使用寿命则是判断制动软管性能的重要因素之一。介绍常见的传递非石油基制动液的汽车制动软管布置形式,从结构和材料两方面重点分析了制动软管寿命的影响因子。介绍一种新型软管仿真软件,利用该仿真软件优化制动软管布置,以提高制动软管在汽车上的使用寿命。     

Numerical Simulation of Mechanically Mixed Layer Formation at Local Contacts of an Automotive Brake System

Processes taking place at local contacts in an automotive brake system are analyzed on the basis of computer simulation with the method of movable cellular automata. The conditions of a mechanically mixed layer (MML) formation on the tribosurfaces and the influence of the layer on the friction coefficient are investigated. The results show that the MML formation leads to the stabilization of the coefficient of friction at a convenient range (0.3–0.4) for brake application. The presence of graphite particles in the MML decreases the critical value of local normal stress for switching from stick-slip to smooth relative motion with MML formation.