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毕业设计（论文）译文毕业设计（论文）外文翻译题 目 汽车盘式制动器摩擦 磨损性能与固体润滑剂专 业 车辆工程 班 级 学 生 指导教师 汽车盘式制动器摩擦磨损性能与固体润滑剂文摘在汽车制动系统、高的温度和压力下产生的接触表面。这一切影响着垫和阀瓣材料,创造一个电圈之间的摩擦表面,由穿粒子和挥发性反应物从垫和阀瓣获得合适的摩擦学性能,垫矩阵包含20个不同的成分,主要选自经验。在本报告的影响已经研究了固体润滑剂在三个不同的垫以相对少的元件作为矩阵相比其余的刹车片。这些成分的组成是相当复杂的，这是众所周知的性能和稳定的摩擦系数。摩擦系数和磨损率进行了测功机垫,模拟真实的汽车制动系列活动。两个不同的能级和两个环境温度均包括在内。在这些试验中,分析了制动盘表面能量色散x射线EDX。电子光谱和光钻AES。结合氩离子溅射法研究了横向和深入的微观分布和水面以下的元素,寻找痕迹的摩擦的原理。这些实验是用来讨论中的摩擦学性能之间的关系和外部变量-制动器温度、固体润滑剂和垫矩阵。为1999农业科技有限公司版权所有。关键词:摩擦学;汽车制动器;固体润滑剂、摩擦流延膜表面分析1、介绍他开发新垫材料是一个复杂的物质为组件之间的交互和协同难以展开起来。通常,选择不同的部件都是基于经验,这意味着一些组件的增加更多基于传统的原因,而不是在了解制动性能的影响。在接触区之间的阀瓣和垫、能量和热量消退。如此一来,一种方法是创造摩擦接触区。这垫圈的角色取决于摩擦衬垫配方中。金属物品已知的领域和稳定的摩擦系数,但更具体的效果尚不清楚。虽然他们通常是非常昂贵的,因此增加了主要用于原始设备主机和原配件海洋能。从而更好地了解影响的增加这些组件,可以提高研究过程和使用受到限制降到最低的价格,这是一个在世界汽车工业中非常重要的问题。其他团体的形成进行了研究摩擦的领域。他们在寻找涂膜性能的影响,对摩擦系数，一个坚实的转移的化学结构,研究了x射线能量分散领域的EDX。XPS和成像的沃思等问题。一个时期被称为时间,在此期间摩擦力波动减少的资料数量达到稳定条件转移。添加剂的具体作用就相对铁氧在阀门中,起到明显的作用。铁层的形成对石棉刹车片钢表面上滑动,利用了扫描电镜进行测试。从以往的研究经验对摩擦学试验下电影的样本显示硬球轴承钢一层很薄的膜大约30的样子。参考上面都有激发我们研究金属硫化物的影响,形成一个摩擦点及其影响制动系统的表面显示特定的光盘和摩擦磨损行为.2、材料和实验程序2.1、摩擦衬垫配方三种不同的设计,特别是对基础矩阵这个项目,他们得到简化,对照商业刹车垫。矩阵是:无金属纤维高考。和两个与金属纤维含量低Low1和Low2。很简单的高考只有六个部件,而Low1和Low2是14成分。三种不同的金属硫化物被添加到基础矩阵来检查他们的影响。贴上不同的刹车片与基地矩阵和各自的添加剂,例如,Low1-Cu是标签的基础矩阵Low1 8 % 2秒vol.铜中,Low1-Ref选定基地Low1没有金属硫化物矩阵。在这种情况下,vol. % 1是调整平等桌子共有100%的成分的刹车片。2.2、摩擦学试验样品测试是在测功机配备一辆车的刹车卡钳。两个测试程序-一个在低,一个在高职用于检测金属硫化物的影响在两个不同的能量输入。检验一个低的标准，包括600个周期进行智能制动以温度50以下来进行观察。当温度下降到50C时,下一个制动周期开始。执行每一个制动以不变的制动压力、制动转矩的测量过程中,摩擦系数的比值提取动量和制动压力测量乘以恒定值为会计的几何学。在一个类似的程序中进行研究分析,并归纳成参数表2。在每个测试一个新的碟安装在钻机。这光盘使用的是标准后盘沃尔沃unven-tilated。经检测,根据阀瓣标示类型的摩擦材料和测试程序,例如,Low1-Sb-1A与矩阵与锑的基地Low1测功机测试后,阀瓣切成块14 14平方毫米用锯子而冷却以防止活动流体加热。样品都储存在之前大气的分析中。磨损的变化量作为垫层厚度和重量损失摩擦材料相比,穿圆盘估计的要低得多,因为它是不可估量的，所以使用千分尺螺丝。2.3、表面分析 首先,分析了样品的阀瓣在Jeol强电子显微镜和一个35 EDAXe EDX系统。分析确是一个现场分析,使用一个初级能源15强。构图计算与EDAXe峰的计算机程序,适合的背景与一个光滑函数和谱减去它从光谱。比较和评述的标准峰值,从数据库中与ZAF-method w5x进行比较。盘的表面,用扫描电镜检查,塑造一个形象与二次电子逐出表面。combi-nation SEMrEDX的是一个强大的工具,以获得更快速的概要双方的地形和主要成分的表面大数量的样品在很短的时间。 后来,一个选择的样品是进行电子光谱AES钻。这是做了3层强原电子入射能量结合深度profil-ing氩离子溅射用1.1分钟之间每个记录频谱。这种分析方法是非常敏感的,并给出了其表面浓度随深度compo-nents作为光谱之间的每一周期记录氩铁溅射业务。在AES中人们可以看到其他元素比和EDX,例如,氧气和二氧化碳这被认为具有重要意义的发现。3 、结果3.1 、摩擦磨损平均水平为每一个制动摩擦测量仪测试周期1和2。一个如图1，这两个图展示了摩擦度发展从一开始直到最后。在那个阶段摩擦水平比较稳定,分析研究了表面存在摩擦。这些结果是典型的所有摩擦材料,但仍有变动之间的摩擦度三个基础矩阵。显示结果的磨损和摩擦在图二形象化摩擦值的平均值测量摩擦后的阶段摩擦已趋稳,这是在200年和100年分别测功机测试一个停止为2。一个比较不同摩擦材料为一个很少显示测功机测试磨损的变化,在0.10.3毫米。摩擦不同于0.36 0.53。针对三种基本矩阵对某人的摩擦是最高的2秒3,在0.47至0.49之间,和一个小低PbS,大约0.40 -0.47。最大的变化是见过用铜年代,为测功机测试,更穿不同的摩擦材料,从1.5毫米。磨损是迄今为止的最高为基数矩阵和低得多的。再加上金属硫化物的磨损提高,且情况相对来说严重。添加铜之后导致较高的磨损,有时候却有较低的摩擦。重复测量显示一些变化对于两摩擦磨损。差异是5 - 10%的摩擦,20 - 30%衬垫的磨损。几个因素造成的磨损大变化。在重量、测量、磨损粒子并非移除。受测厚仪的永久膨胀加热后的垫。不同的粗糙度,这可能会导致在不同情况下结果不同。3.2、 SEM盘的表面,用扫描电镜检查,而创造出图像的二次电子逐出表面。图象反映一个依赖的两对地形和构成。图3显示图像测试新的阀瓣之前和之后15强和放大扫描。从下面的纵向线条的加工阀瓣。除此之外,两个不同的领域是环绕。一个区域看起来光滑科学其他地区粗糙。两种类型的领域是建立在所有阀瓣包括新的阀瓣。下一段介绍了EDX考试结果证明粗顺利地区性质的摩擦的电影。3.3 、EDX分析经检测,分析了所有的光盘和EDX和粗糙区流畅。总体结果进行了分析讨论通过比较两种阀瓣,一个测试,对参考资料没有金属硫化物和其他测试,对摩擦材料的硫化锑。从样品,样品的变化与个人摩擦材料间的差异。从现场的散射反射点一个样品表面形貌;因此,光滑的相似地区组成。一个典型的例子的分析圆盘EDX是显示在无花果饼来。第四款、第五款分别给出两种成分与光滑粗略部分的光盘。光谱图4中一个和图5 a都记录在一个光滑的地区。这位前没有显示比其他部件从阀瓣:硅、铁和锰。后者显示一些相似点图4 b和图5 b,也载入在崎岖不平的地区的光盘。这些光谱峰组件包含从起源在垫矩阵。几个分量的存在与起源在垫摩擦材料表明转会。锑、硫之间的比值,钡和硫,这都是原创的化合物在垫,是特别有趣的。如果发生了化学变化,其比例阀瓣应该有改变从价值观的原始材料。.Wear 232 1999 168175 rlocaterwear Tribological properties of automotive disc brakes with solid lubricants Luise Gudmand-Hyer a,), Allan Bachb, Georg T. Nielsenc, Per Morgena a Physics Department, Odense Uniersity, Campusej 55, 5230 Odense M, Denmark b Roulunds Fabriker, Hestehaen 51, 5260 Odense S, Denmark c Tristan, Kochsej 1, 2600 Glostrup, Denmark Abstract In automotive brake systems, high temperatures and pressures are generated at the contacting surfaces. This affects the pad and disc materials, creating a friction film between the surfaces, which consists of wear particles and volatile reactants from the pad and disc. To acquire suitable tribological properties, a pad matrix contains up to 20 different ingredients, mainly selected from experience. In the present report the effect of solid lubricants has been studied in three different pad matrices with relatively few components as compared to commercial brake pads. The components are Cu S, PbS and Sb S , which are known to modify and stabilise the friction coefficient. The 223 friction coefficient and wear rates of the pads are examined on a dynamometer, which simulates series of real-life car brake events. Two different energy levels and two ambient temperatures are included. After these tests, the brake disc surfaces are analysed with energy .dispersive X-ray EDX and Auger electron spectroscopy AES in combination with argon ion sputtering to study the microscopic lateral and in-depth distribution of elements on and below the surface, looking for traces of the friction film. These experiments are used to discuss the correlation between the tribological properties and the external variables braking temperature, solid lubricants and pad matrix. q1999 Elsevier Science S.A. All rights reserved. Keywords: Tribology; Automotive brakes; Solid lubricants; Friction film; Surface analysis 1. Introduction The development of new pad materials is a complicated matter as the components interact and synergetic effects that are hard to disentangle arise. Quite often, the selection of the different components is based on empirical experi- ence, which means that some components are added for reasons based more on tradition and less on knowledge about their influence on the brake performance. In the contact zone between the disc and pad, energy is trans- ferred and heat is dissipated. As a consequence, a friction film is created in the contact zone. The character of the film depends on the friction pad formulation. Metal sul- phides are known to modify and stabilise the friction coefficient, though the more specific effects are not well known. They are usually added though very expensive and .therefore primarily used for original equipment OE and ) Corresponding author. Tel.: q45-65573509; fax: q45-65158760; E-mail: lghfysik.ou.dk .original spare parts OES . Thus a better knowledge of the effects of adding those components can improve the opti- misation process and limit their use to minimise the price, which is an important issue in the car industry. Other groups have studied the formation of the friction film. They looked for the influence of the film properties on the friction coefficient. The chemistry of a solid transfer .film was studied with energy-dispersive X-ray EDX and w ximaging XPS by Wirth et al. 1 . A wear-in period has been described as the time during which the friction is fluctuating with decreasing amount of material transfer as stable conditions are reached. The specific role of additives with respect to the relative amount of iron and oxygen in w xthe discs was discussed recently by Holinski2 . The formation of an iron layer on asbestos brake pads sliding w xover steel surfaces has been investigated by Scieszka 3 with SEM together with tribo-oxidation. Experience from previous studies on friction film for- mation under tribological testing with samples of hard ball w x bearing steel indicated a very thin film of around 30 A 4 . The references above have inspired us to study the effects of metal sulphides on the formation of a friction 0043-1648r99r$ - see front matter q 1999 Elsevier Science S.A. All rights reserved. .PII: S0043-1648 99 00142-8 ()L. Gudmand-Hyer et al.rWear 232 1999 168175169 Table 1 The composition of the friction materials is given in vol.%. The numbers in parenthesis indicate the reference friction material without metal sulphide .Main elementCharacteristic namesNmet vol.%Low1 vol.%Low2 vol.% .FibreOrganic aramid5 5.411 125 5.4 .Metal9 9.8 .Other inorganic18 19.615 16.318 19.6 .FillersBarytes, friction dust, and vermiculite41 44.625.5 27.729 31.5 .MetalsBrass5 5.49 9.8 .AbrasivesZirconium silicate5 5.45 5.4 .Aluminium oxide0.5 0.5 .BindersResin, rubber23 25.026 28.326 28.3 . . .Metal sulphideCopper, lead or antimony sulphide8 08 08 0 Total vol.%100100100 film in a brake system and its effect on the surface of the disc as indication of specific wear and friction behaviour. 2. Materials and experimental procedures 2.1. Friction pad formulation Three different base matrices are designed especially for this project, and they are simplified and compared to a commercial brake pad. The matrices are: one with no .metal fibre Nmet and two with a low content of metal .fibreLow1 and Low2 . The Nmet is very simple with only six components while Low1 and Low2 consist of 1314 constituents. Three different metal sulphides are added to the base matrices to examine their effects. We labelled the different brake pads with the base matrix and the respective additive, e.g., Low1-Cu is the label of base matrix Low1 with 8 vol.% Cu S added, and Low1-Ref 2 designates the base matrix Low1 without metal sulphide. In this case the vol.% in Table 1 are adjusted to equal a total of 100% of the components in the brake pads. 2.2. Tribological tests The samples are tested on a dynamometer equipped with a car brake caliper. Two test procedures one at low and one at high duty are designed to examine the effects of the metal sulphides at two different energy .inputs. The test at low duty 1A consists of 600 braking cycles performed from 50 kmrh down to rest. When the temperature of the disc has decreased to 508C, the next braking cycle begins. Each braking is performed with a constant braking pressure. During braking the torque is measured, from which the friction coefficient is extracted as the ratio between measured momentum and braking pressure multiplied by a constant value accounting for the geometry. A similar procedure is performed at high duty .2A , and the parameters are summarised in Table 2. Before each test a new disc is mounted on the rig. The discs used are Volvo standard rear discs, which are unven- tilated. After testing, the discs are labelled according to type of friction material and test procedure, e.g., Low1-Sb- 1A corresponds to base matrix Low1 with antimony sul- phide tested at 1A. After the dynamometer testing, the discs are cut into pieces of 14=14 mm2with a saw while cooling with a commercial fluid to prevent heating. The samples are stored in atmospheric air before analysis. The wear of the .pads is measured as change of thickness mm and weight .loss g . Compared to the friction material, the wear of the discs is estimated to be much lower as it is immeasurable using a micrometer screw. 2.3. Surface analysis First, the samples of the disc are analysed in a Jeol 35 keV electron microscope with an EDAXe EDX system. The analysis is performed as a spot analysis, using a primary energy of 15 keV. The composition is calculated from the peaks with the EDAXe computer program that fits the background of the spectra with a smooth function and subtracts it from the spectrum. The peaks are com- pared to standard spectra from a database, and evaluated w xwith the ZAF-method 5 . The surfaces of the discs are examined with SEM in which an image is created with secondary electrons ejected from the surface. The combi- nation SEMrEDX is a strong tool to get a quick overview Table 2 Dynamometer tests 1A and 2A, indicating the initial velocity from which the braking is performed, the initial temperature of the disc when each braking cycle begin, and the applied brake pressure. The cycles are repeated N times DynamometerVelocityTemperaturePressureStop no. .testkmrh8CbarN 1A507030600 2A12020040350 ()L. Gudmand-Hyer et al.rWear 232 1999 168175170 of both the topography and the main composition of the surface of a large number of samples in a short time. Afterwards, a selection of the samples is examined with .Auger electron spectroscopy AES . This is done with 3 keV primary electron energy combined with depth profil- ing using 1 keV argon ion sputtering for 1 min between each recorded spectrum. This analysis method is very surface sensitive and gives the concentration of the compo- nents with depth as spectra are recorded between each cycle of argon iron sputtering. With AES it is possible to see other elements than with EDX, e.g., oxygen and carbon which are believed to play an important role in the formation of a friction film. 3. Results 3.1. Friction and wear The average friction levels measured for each braking cycle for dynamometer tests 1A and 2A are shown in Fig. 1. The two graphs show how the friction level develops .from the beginning, during conditioning bedding-in until the end. At that stage the friction level is stable and the surfaces are analysed to study the existence of a friction Fig. 1. The friction levels of different brake couples measured on a dynamometer. The shown friction material is base matrix Low1 with .Cu S, PbS or Sb S , and the reference without a metal sulphide.a 223 .Dynamometer test 1A. b Dynamometer test 2A. Fig. 2. Dynamometer results. The average friction of the different friction . .materials tested against cast iron brake discs B . The pad wear = . a .Dynamometer test 1A. b Dynamometer test 2A. film. These results are typical for all friction materials, though with some variations in the friction level between the three base matrices. The results of wear and friction are visualised in Fig. 2. The friction value is the average value of the measured friction after the bedding-in period when the friction has stabilised, which is respectively after 200 and 100 stops for dynamometer test 1A and 2A. A comparison of the differ- ent friction materials for dynamometer test 1A shows little variation of the wear, around 0.10.3 mm. The friction varies from 0.360.53. For all three base matrices the friction is highest for Sb S , around 0.470.49, and a little 23 lower for PbS, around 0.400.47. The largest variations are seen with Cu S, from 0.370.53. For dynamometer 2 test 2A, the wear varies much more with the friction material, from 1.56.5 mm. The wear is by far highest for base matrix Nmet and much lower for Low1 and Low2. The addition of one of the metal sulphides to Low1 improves the wear, and the situation is opposite for Low2. Addition of Cu S leads to relatively higher wear and 2 .sometimes lower friction. The repeated measurements show some variations for both friction and wear. The variation is 510% on the friction, and 2030% on the pad wear. Several factors cause the large variations of wear. Before the weight ()L. Gudmand-Hyer et al.rWear 232 1999 168175171 measurement, wear particles are not removed. The thick- ness is affected by the permanent swell of the pads after heating. The roughness of the discs varies, which can cause different wear during bedding-in. The result is there- fore to be used merely as indication of the trend. 3.2. SEM The surfaces of the discs are examined with SEM in which the image is created with secondary electrons ejected from the surface. The image reflects a dependency both on topography and composition. Fig. 3 shows an image of a new disc before and after testing scanned with 15 keV and magnified 400=. The underlying longitudinal lines are from the machining of the disc. Apart from that, two .different areas are circled. One area looks smooth S and .the other area is roughR . Both types of areas are found on all the discs including the new disc. The next paragraph presents the results of EDX examinations of the rough and smooth areas to demonstrate the character of the friction film. 3.3. EDX analysis After testing, all the discs have been analysed with EDX at a smooth and rough area. The overall results are discussed by comparing two discs, one tested against the reference material without a metal sulphide and the other tested against a friction material with antimony sulphide. The variation from sample to sample is comparable to the differences between the individual friction materials. The scatter from spot to spot on one sample reflected the surface topography; thus, the smooth areas were similar in composition. A typical example of the EDX analysis of the discs is shown in Figs. 4 and 5 of Low1-Sb-1A and Low1-Sb-2A, .respectively, giving the composition of both a roughR .and a smooth S part of the discs. The spectra in Fig. 4a .and Fig. 5a are both recorded at a smoothSarea. The former shows no other components than those from the disc: silicon, iron and manganese. The latter shows some similarities with Fig. 4b and Fig. 5b, which are recorded at .roughR areas on the discs. These spectra contain peaks from components with origin in the pad matrix. The existence of several components with origin in the pad indicates a transfer of friction material. The ratios between antimony and sulphur, and barium and sulphur, which are original compounds in the pads, are especially interesting. If chemical changes have taken place, their ratios in the discs should have changed from the values of the original material. The element concentrations for Low1-Sb-1A and 2A and Low1-Ref-1A and 2A are calculated from the spectra, as shown in Table 3. For all eight measurements shown, except for Low1-Ref-1A, the ratio MnrFe is almost the same. At the rough areas, the ratio BarS and SbrS are the . .same for Low1-Sb-1AR and Low1-Sb-2AR , but the concentrations are different. This indicates that the surface layers are similar and that the same reactions have taken place, but the thickness of the layers is different. At the smooth areas no antimony and barium is found .for Low1-Sb-1A S , only sulphur, copper, and zinc. This .is in contrast with the spectrum of Low1-Sb-2A S , which .contains the same elements as Low1-Sb-2ARbut the ratios between the elements are different. Compared to . .Low1-Sb-2A S , Low1-Ref-2A S contains 10 times less sulphur and no barium, indicating that no friction material . .Fig. 3. Typical SEM images of a cast iron disc before and after testing on a dynamometer. The rough R and smooth S areas are indicated with a circle. . .a New disc. b Low1-Sb-2A. ()L. Gudmand-Hyer et al.rWear 232 1999 168175172 . .Fig. 4. Typical EDX-spectra measured on the cast iron disc surface tested against friction material Low1-Sb-1A. The spectra are recorded on a a smooth area and b a rough area. ()L. Gudmand-Hyer et al.rWear 232 1999 168175173 . .Fig. 5. Typical EDX-spectra measured on the cast iron disc surface tested against friction material Low1-Sb-2A. The spectra are recorded on a a smooth area and b a rough area. ()L. Gudmand-Hyer et al.rWear 232 1999 168175174 has been transferred at the smooth areas for the reference material. The ratio ZnrCu is the same for Low1-Ref-1A . .S and Low1-Ref-2A S . 3.4. AES depth profile The existence of antimony on the surface can be ob- served in Fig. 6 showing a decreasing concentration with depth; thus, antimony has been transferred and dissolved at the very upper surface of the disc. The amounts of iron, oxygen and carbon also change with depth. The oxygen concentration follows the iron concentration closely, in- creasing with depth whereas the carbon concentration de- creases. The ratio between iron and oxygen indicates that a homogeneous phase of FeO has formed at the surface. This iron oxide phase is stable compared to higher oxidation w xlevels and is discussed by Jansson et al. 6 . A further discussion of the AES analysis of all samples is to be published later in relation to a discussion of the general concepts of formation of the friction film. 4. Discussion It takes many small bits of information to create a full picture of the effects, e.g., to see which constituents have been transferred and which are gone or not active. Also, the atomic stoicheiometric percentages indicate if there has been any chemical change. When one component is pre- sent with a different relative amount than the original constituent, as in the case of barium sulphate and antimony sulphide, it indicates a chemical reaction. The present measurements and procedures allow for at least a partial understanding of the friction film formation process. This is definitely demonstrated here with Low1- Sb-2A where a friction film forms at 120 kmrh, 2008C, and a brake pressure of 40 bar at the presence of antimony sulphide in the pad. In this case, even smooth-looking areas of the disc have undergone compositional modifica- tion, as shown with EDX. The presence of sulphur moni- Table 3 Surface concentration measured with EDX of the cast iron discs tested with the friction materials Low1-Sb and Low1-Ref analysed at smooth . .S and roughR areas on the discs ElementLow1-Sb-1ALow1-Sb-2ALow1-Ref-1A Low1-Ref-2A . . . . . . . .SRSRSRSR At.%At.%At.%At.% SiK3.310.3 SK10.00.13.00.112.1 Sb