铝基复合材料的摩擦磨损性能

在制动试验条件下,研究铝基复合材料的摩擦磨损性能,研究结果表明：与铸铁材料相比,铝基复合材料能大大地降低摩擦表面温度,其摩擦系数可在较大载荷,较高转速下保持稳定,有利于制动性能的提高,复合材料在不同摩擦试验后的磨损量与ＳｉＣ含量和基体种类有关。在相同摩擦条件下,磨损量随颗粒含量增加而减少,与铸铁材料相比,它具有重量轻,导热快,摩擦系数稳定,不产生热裂,是较适宜的制动盘材料。     

银-石墨烯复合材料的滑动摩擦磨损性能

采用球磨混粉、冷等静压和真空烧结的工艺流程制备了含0.5%~2.0%石墨烯的银-石墨烯复合材料,并对复合材料进行销盘式摩擦磨损试验以研究其大气环境滑动摩擦磨损性能。研究结果表明,因石墨烯易团聚,石墨烯含量限于1.5%时能够有效改善复合材料的性能。与未增强的银相比,由于在接触表面形成自润滑碳质膜,银-石墨烯复合材料表现出较低的摩擦系数、较少的磨损量和较低的接触表面温度。随石墨烯含量的增加,复合材料的摩擦系数和磨损量均下降。复合材料的主要磨损机制为粘着磨损和磨料磨损。     

电厂飞灰颗粒增强铝基复合材料的摩擦磨损行为

对挤压铸造制成的飞灰颗粒增强ZL109复合材料在不同条件下的的摩擦磨损行为进行了研究。结果表明：飞灰颗粒的加入可提高铝合金材料的耐磨性,复合材料同基体合金相比,摩擦因数也较低。在摩擦磨损过程中,在较低载荷下复合材料的摩擦表面形成一稳定的摩擦转移层,该转移层的存在可以起到降低摩擦因数的作用。在较高载荷下由于该摩擦转移层遭到破坏,从而影响了其减摩作用的发挥。镶嵌在基体中的飞灰颗粒在摩擦过程中主要起到承受载荷、限制对磨材料与铝基体直接接触的作用。脱落的飞灰颗粒可以起到“滚珠”的作用,在摩擦表面形成“三体”摩擦,从而起到减摩的作用。     

不同成分对C/C-SiC材料摩擦磨损行为的影响与机理

采用温压-原位反应法制备C/C-SiC复合材料,研究了SiC、石墨和树脂炭成分对C/C-SiC材料摩擦磨损行为的影响及其机理.结果表明:SiC在摩擦表面摩擦膜的形成过程中起骨架作用,提高SiC的含量有利于提高摩擦系数,降低磨损率;树脂炭在材料中具有粘结各成分和提高摩擦系数的作用,但其成膜性较差,易增大磨损率;石墨粉在制动过程中起润滑作用,适量石墨粉有助于形成稳定的摩擦膜降低磨损率;摩擦表面摩擦膜的形成有利于减少C/C-SiC材料的磨损率.     

变温条件下石墨形态对缸套铸铁磨损性能的影响

为了研究缸套铸铁材料石墨形态对其磨损过程的影响,选取了灰铸铁、蠕墨铸铁和球墨铸铁3种具有不同石墨形态的铸铁材料为研究对象,分别在不同温度下对其进行了干摩擦磨损实验。结果表明:灰铸铁的摩擦系数及磨损量随温度的上升而上升,而蠕墨铸铁及球墨铸铁随温度的上升呈现先上升后下降的变化趋势;常温下灰铸铁的摩擦系数及磨损量最大,耐磨性能最差;高温时灰铸铁的摩擦系数及磨损量仍然最大,蠕墨铸铁的摩擦系数大于球墨铸铁,但磨损量最小,耐磨性能最优。     

原位Al2O3颗粒增强铜基复合材料的微动磨损特性

采用球-面接触方式,在振幅为300 μm条件下研究了原位Al2O3颗粒增强铜基复合材料在空气和油介质中的往复滑动磨损行为,采用SEM观察磨痕表面形貌,用非接触式表面形貌分析仪测定磨痕的三维表面形貌及磨损体积损失,研究了载荷和介质对复合材料摩擦系数和磨损量的影响.结果表明:在两种介质中铜基复合材料的摩擦系数随着载荷增加而呈下降趋势;铜基复合材料在油中形成的润滑膜可以显著降低摩擦系数;铜基复合材料在空气中的磨损机制为粘着磨损并伴随有少量磨粒磨损,而在油中的磨损机制为磨粒磨损.     

铁基表面复合材料的制备及磨损性能

采用新型制备方法,通过选择大尺寸增强颗粒,改进铁水在陶瓷预成型体中的引入方式以及优化铁水与陶瓷颗粒之间的润湿行为,成功制备了新型铁基表面复合材料,其复合层厚度达25mm以上。该材料与砂轮对磨以及上机试运行的磨损结果均表明,新型铁基表面复合材料磨损量明显低于目前常用的高铬铸铁材料。     

激光表面织构对铸铁摩擦磨损性能的影响

目的找出最佳的表面织构方案,将其应用在摩擦副的表面处理上,从而达到降摩减阻、节能减排的目的。方法设计了两种不同的加工面积占有率(10%和20%),三种不同形状的表面织构(圆坑、椭圆坑、沟槽),对铸铁试件进行激光表面加工,并利用环-块磨损试验机进行油润滑摩擦磨损实验。结果表面织构对铸铁材料的摩擦磨损性能有明显改善,尤其在磨损量方面。三种不同形状的表面织构相比,圆形表面织构试件的磨损量最小。两种不同面积占有率相比,面积占有率为20%的圆形微织构试件的磨损量最小,并在一定程度上减小了摩擦系数。结论在本实验研究条件下,面积占有率为20%的圆形表面织构对改善铸铁材料的摩擦磨损性能最显著。     

A356/SiC_P与列车实用中的有机闸片的滑动摩擦磨损特性

以铝基复合材料作为列车制动盘材料的实用化为目的,选用A356/SiC 20%(体积分数,下同)复合材料和AISI D2工具钢为摩擦材料,以中速列车实用中的有机闸片为对偶材料,进行对比干摩擦磨损试验,并分析比较了磨损特性.结果表明:铝基复合材料在小于200 N(3.98 MPa)的低载荷下,只存在轻微的氧化磨损,耐磨性比实用中的铁合金材料更好;而超过该载荷时,开始发生磨削磨损,磨损量逐步超过铁合金材料,当载荷达到400 N(7.96 MPa)时,由于严重的磨削磨损,磨损量剧增.而铁合金材料则随载荷和滑动速度增加,磨损率缓慢增加;磨损过程中的复合材料的摩擦系数平均值与载荷、滑动速度无关,始终保持0.3～0.4,同时随磨损距离的波动也非常小,而工具钢的摩擦系数平均值则对试验参数的敏感度相对大些,且摩擦系数平均值也比复合材料略小,即摩擦系数方面复合材料具有更好的特性.     

9Cr18和GCr15球-盘摩擦副摩擦学性能分析

利用球－盘摩擦试验机，在大气和真空环境中分别考察了9Cr18和GCr15钢在干摩擦和固体润滑条件下与钢球的摩擦损性能，试验结果表明：两种材料在真空环境中或MoS2基薄膜润滑条件下，摩擦系数都明显低于大气环境或无润滑条件，而且摩擦振动和噪音较低，磨痕表面较光滑，通常的摩擦副在真空环境中的摩擦系数，磨损量比大气中大。研究表明这是由于9Cr18盘表面干摩擦跃迁导致了加工硬化和MoS2基薄膜润滑作用，通过对动态动摩擦系数及其特征值的系统分析，对这两种材料的摩擦过程特性进行了研究。     

Tribological stability of particle reinforced aluminum matrix composites in braking

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High-Speed Tribological and Mechanical Properties of Layered Fe/SiC Composites

In this work, we studied the high-speed tribological and mechanical properties of layered SiC particulate reinforced iron matrix composites. The layered composites consisted of a surface layer with high volume fraction of the reinforcement particles and a layer with low volume fraction in the bulk. The layered composites are a form of functionally graded materials with high wear resistance near the surface and high thermal conductivity in the bulk. The composites were prepared by standard powder metallurgy techniques. The tribological behavior of the composites was evaluated at 25 to 35 m/s sliding speeds using a sub-scale dynamometer disk brake testing system. The properties of the layered composites were compared to those of uniform composites. The results showed that the layered composites have better wear resistance and braking effectiveness in the range of braking speeds considered. The layered composites also showed higher bending strength than the monolayer composites due to the presence of the interfaces between the layers.     

Friction and wear characteristics of polymer-matrix friction materials reinforced by brass fibers

This study is an investigation of friction materials reinforced by brass fibers, and the influence of the organic adhesion agent, cast-iron debris, brass fiber, and graphite powder on the friction-wear characteristics. Friction and wear testing was performed on a block-on-ring tribometer (MM200). The friction pair consisted of the friction materials and gray cast iron (HT200). The worn surface layers formed by sliding dry friction were examined using scanning electron microscopy (SEM), x-ray energy-dispersive analysis (EDX), and differential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showed that the friction coefficient and the wear loss of the friction materials increased with the increase of cast-iron debris, but decreased with the increase of graphite powder content. The friction coefficient and wear loss also increased slightly when the mass fraction of brass fibers was over 19%. When the mass fraction of organic adhesion agent was about 10–11%, the friction materials had excellent friction-wear performance. Surface heating from friction pyrolyzes the organic ingredient in the worn surface layer of the friction materials, with the pyrolysis depth being about 0.5 mm. The surface layers were rich in iron but poor in copper, and they were formed on the worn surface of the friction material. When the mass fraction of brass fibers was about 16–20%, the friction materials possessed better wear resistance and a copper transfer film formed on the friction surface of counterpart. Fatigue cracks were also found in the worn surface of the gray cast-iron counterpart, with fatigue wear being the prevailing wear mechanism.     

蠕墨铸铁在铁道车辆制动系统中的应用研究

在分析车辆制动器摩擦温度场的基础上 ,研究蠕墨铸铁在铁道车辆制动系统中的使用性能 ;研究结果表明 ,在车辆制动器服役条件下 ,摩擦速度与接触压力的提高 ,摩擦副的摩擦系数显著降低 ,磨损率显著增加 ;在所研究的不同石墨形态的铸铁中 ,蠕墨铸铁不但具有低而稳定的磨损率 ,而且具有高而稳定的制动性能 ,是制造车辆制动器部件的合理选材。     

Tribological characteristics of compacted graphite cast iron in dry sliding condition

In tribological system, friction pairs are the core.Different friction pairs show different tribologicalcharacteristics. Dry sliding friction means that there is noliquid lubricator in the process of wear and friction. Inmost cases, friction surfaces contact each other directly,while under some operating conditions, there exists solidlubricant. Among many friction pairs studied, the drysliding friction pairs with background of practicalapplication for brake system increasingly attract theatten…     

STUDY ON THE SiC_p./Al-ALLOY COMPOSITE AUTOMOTIVE BRAKE ROTORS

1. IntroductionThe SiC particulate reinforced aluminum matrix composites (AMC) have sucll characteristics as high specific stiffness and strength, high wear resistance, high thermal condllctivity, and lightweight etc. Using such lightweight material, as aluminum matrix compositein brake systems is one of the ways to reduce unsprung weight of motor vehicles. Thetribological and wear behavior of the aluminum matrix composite have been reported bydifferent ...ea.chers[1--4], and AMC brake roto…     

Abrasion Mechanism of Stainless Steel/Carbon Fiber-Reinforced Polyether-Ether-Ketone (PEEK) Composites

A new type of composite material, stainless steel fiber and carbon fiber-reinforced polyether-ether-ketone (PEEK), was investigated to study its friction and wear properties and mechanisms. The friction materials containing 11 ingredients were hot-pressed and tested using a pad-on-disc type wear tester under unlubricated sliding friction and wear conditions at a constant sliding speed. The worn surface morphology was observed by Field-emission Scanning Electron Microscope (FE-SEM) and Atomic Force Microscope (AFM). The role of transfer film was studied using X-ray photoelectron spectroscopy (XPS) to investigate the thermal decomposition of the friction material. The fade ratio of the composites was only 4.8%, the recovery ratio 107%, and the total wear ratio was as low as 0.99 × 10⁻⁷ cm³(N m)⁻¹, showing the perfect properties of heat stability and recovery, as well as high antiwear ability of the composites. Adherence abrasion and particle abrasion take place at higher temperature. A transfer film is formed, which may improve abrasive resistant performance to get stable friction coefficient and low abrasion value for composite friction materials.