块式制动器摩擦磨损特性的实验研究

以块式制动器实物进行了摩擦磨损特性实验,发现制动衬垫比压、制动初速度和制动器温度对摩擦系数有显著影响,制动衬垫比压对单位摩擦功的制动衬垫线磨损率无显著影响;摩擦系数和单位摩擦功的制动衬垫线磨损率均可用正态分布来描述。并指出制动器设计或选用时应考虑制动衬垫比压和制动初速度两因素。     

石油钻机盘式刹车副材料的摩擦磨损性能研究

为提高深井石油钻机盘式刹车副的摩擦学性能和使用寿命,研制开发了新型刹车盘表面堆焊材料和无石棉刹车块摩擦材料,并通过变温摩擦磨损性能实验,研究了刹车副的摩擦学性能。研究表明,刹车副具有良好的变温摩擦特性和高温抗热衰退性能,高温下的摩擦因数比较稳定;刹车块和刹车盘的磨损率均随温度的升高而增大,但刹车盘表现出相对稳定的耐磨性能。载荷对刹车副的摩擦因数影响不大,变化比较平稳;刹车块和刹车盘的磨损率均随载荷的增大而增大,但刹车块表现出相对稳定的耐磨性。刹车副的摩擦因数随滑动速度的增加而增大,并趋向平稳;但速度对刹车块和刹车盘的磨损率影响不大,变化相对稳定。研制的刹车副材料能够满足石油矿场钻机作业的要求。     

Wear mechanism of disc-brake block material for new type of drilling rig

To improve friction and wear performance and service life of the disc-brake pair material of a drilling rig, a new type of asbestos-free frictional material with better performance for disc-brake blocks is developed, and its wear mechanism is investigated by friction and wear experiments. Topography and elementary components of the brake block’s wear surface are analyzed by employing SEM and EDAX patterns, revealing its tribological behaviour and wear mechanism. When the frictional temperature is lower, the surface film of the brake block is thinner, dense, smooth with plasticity, and divided into the mixture area, Feabundant area, carbon-abundant area and spalling area. The mixture area consists of various constituents of frictional pairs without ploughing and rolling trace. The Fe-abundant area mainly consists of iron and other constituents. The carbon-abundant area is the zone where graphite and organic fibre are comparatively gathered, while the spalling area is the zone where the surface film is spalled and its surface is rough and uneven, with a loose and denuded state. During the period of high frictional temperature, the frictional surface is also divided into the mixture area, Feabundant area and spalling area. In this case, the mixture area consists of abrasive dust from friction pairs, and the surface film is distributed with crumby hard granules, exiguous oxide, carbide granules and sheared slender fibre. The Fe-abundant area is mostly an oxide layer of iron with a flaky distribution. Fracture and spalling traces as well as an overlapping structure of multilayer surface films can be easily found on the surface film. The components of the spalling area are basically the same as that of the matrix. At the beginning of wear, the hard peaks from the friction surface of the disc-brake plough on the surface of the brake block. With increasing frictional temperature, the friction surface begins to soften and expand, and oxidized wear occurs at the same time. During the high-temperature wear period, severely influenced by friction heat, obvious softening and plastic flow can be found on the friction surface of the brake block, its anti-shearing ability is weakened, and adhesive wear is intensified. Thermal decomposition of cohesive material in the brake block is simultaneously strengthened, so that constituents shed due to loss of adhesion. Organic fibre is in a flowing state and obviously generates drawing, shearing, carbonization and oxidization. In addition, thermal cracking, thermal oxidization, carbonization and cyclization of organic substances on the surface of brake block can make the friction surface produce pores or cracks, thus fatigue wear occurs.     

材料干滑动摩擦磨损性能的研究进展

介绍高温、高速、载流、气氛、磁场等苛刻条件下材料的干滑动摩擦磨损特性的研究方法和研究结果。得到以下几点结论:材料的干摩擦磨损特性与速度、载荷之间存在着对应关系,当pv值超过临界值后,材料的摩擦因数和磨损率发生突变;摩擦面温度的升高会降低材料的干摩擦磨损性能;环境气氛的改变不影响金属摩擦副pv特性的基本规律,但显著影响其摩擦因数和磨损率数值的大小;电流的存在恶化材料的干摩擦性能;施加磁场可显著改善材料的摩擦磨损性能,并且磁场强度是影响材料干摩擦特性的主要因素。     

PCrNiMo材料摩擦磨损特性研究

采用自制的销盘式干滑动摩擦磨损试验机,研究了不同硬度炮钢材料PCrNiMo自配副时的摩擦磨损特性。研究结果表明：材料的磨损率随着速度、载荷的增加而增大,摩擦因数随着速度、载荷的增加而减小;低速低载条件下,接触表面以磨粒磨损为主,而在高速、高载条件下,接触表面以粘着磨损形式为主。     

基于马尔可夫链的飞机刹车片检查时间确定

为结合飞机实际运行工况,科学合理地制定刹车片检查时间,笔者提出一种基于马尔可夫链理论的预测模型。以某一机群刹车片检查时间确定为实例,分别论述了刹车片磨损状态的划分,转移概率矩阵的构造与估计,并对该机群刹车片磨损状态进行了预测,其预测结果与实际检查情况较吻合。根据刹车片磨损状况的预测结果,制定了该机群在实际运行工况下的刹车片检查时间。实际运行情况表明,所制定的刹车片查检时间可行、有效。     

Triboengineering properties of polytetrafluoroethylene modified by thermally expanded graphite

The paper studies the effect of thermally expanded graphite upon the triboengineering, strain, and strength characteristics, as well as the thermodynamic and structural parameters of polytetrafluoroethylene as dependent on its concentration. Introduction of graphite filler was found to lead to improvement of compressive strength, elasticity modulus, and wear resistance of the polymer. In addition, thermally expanded graphite promotes adaptation of the composite surface layer to frictional conditions.     

四种车辆制动闸瓦材料摩擦特性试验研究

使用MM-1000型摩擦试验机,在不同的压力和速度下作了4种铁路车辆制动闸瓦材料与车轮钢的摩擦试验,测试它们的制动摩擦特性。试验结果表明,闸瓦材质对制动摩擦性能有较大的影响。高磷铸铁A、B两种材料的摩擦因数比较不稳定,在制动过程中摩擦因数出现了较大的波动,而且易受制动压力和速度的影响。高分子树脂复合材料C的摩擦因数比较稳定,受制动速度的影响较小但是受压力的影响较大。高分子树脂复合材料D的摩擦因数受制动速度的影响较大,但是受制动压力的影响则较小。     

Triboengineering and physicomechanical properties of nanocomposites based on PTFE and aluminum oxide

The paper discusses the tribological and physicomechanical properties of composites on the base of polytetrafluoroethylene and different grades of nanosize aluminum oxide powders as dependent on the filler content, technology of combining the ingredients, and operating temperature. It is shown that introduction of nanosize aluminum oxide significantly changes the triboengineering characteristics of the polymer, including the friction coefficient and temperature in the friction zone, which decrease and stabilize. The friction coefficient of the composite is found to decrease with increasing filler content.     

植物性食品中稀土元素的快速测定

采用微波消解处理样品,消化液直接用ICP-MS进行分析,以建立植物性食品中稀土元素的快速测定方法。实验结果证明,该方法检出限0.01～0.2μg/kg,精密度优于10%,对3个标准参考物质的分析结果令人满意。利用该方法对植物性食品中稀土元素进行测定,完成检测只需1～2h,满足日常检验需求,较大地提高工作效率。     

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.     

Investigation of wear resistance of a hard alloy modified by nanoaddititives

The effect of additions of nanostructured tungsten carbide powder into a sinter mixture with compaction of sintered hard alloy VK8 on its tribological properties has been studied. Physicomechanical properties of the material obtained have been estimated. The produced hard alloy shows elevated wear resistance to abrasive wearing.     

Al2O3增强粉末冶金铜基摩擦材料摩擦磨损性能研究

为提高铜基粉末冶金摩擦材料的耐磨性及制动效果,使用粉末冶金法（PM）制备氧化铝增强铜基摩擦材料,采用布氏硬度计、扫描电子显微镜（SEM）、能量色散光谱仪（EDS）等测试手段以及摩擦磨损实验,研究氧化铝的掺杂对摩擦材料微观组织和摩擦行为的影响。结果表明：在制备的铜基摩擦材料中,氧化铝硬质颗粒在铜基体中分布均匀,由于硬质相的存在所形成位错钉扎效应对复合材料的硬度有大幅的提升,而对材料的密度有一定的消极作用。摩擦实验结果显示,氧化铝可以提高材料的摩擦因数并增强其耐磨性;且随着载荷的增大Al2O3-Cu复合材料的摩擦因数较高且稳定性较好,磨损率有明显的降低,表明氧化铝的掺杂对铜基材料有显著的增强效果。通过光学显微镜以及EDS分析得出,Cu基材料的主要磨损机制为氧化磨损和黏着磨损,而Al2O3-Cu材料的磨损机制为氧化磨损和磨粒磨损组成的混合磨损。     

Tribological materials based on polytetrafluoroethylene modified by a liquid lubricant

Technologies are developed for the production of polymeric materials based on polytetrafluorethylene with a microporous structure providing high sorption capacity towards liquid lubricants and for impregnating liquid lubricants into the polymer composites. The tribological properties of the polymeric materials containing liquid lubricants and natural adsorbents are studied. The new materials display a long-lasting self-lubrication effect and increased bearing capacity; they may be employed in friction units of different purposes.     

无石棉制动带摩擦磨损性能预测系统的研究

以实验为基础,利用Matlab软件平台上的BP神经网络工具箱,建立并训练了无石棉制动带复合纤维优化设计中所需的各纤维组分体积百分含量与制动带摩擦磨损性能指标之间的人工神经网络映射模型。研究结果表明,该BP网络映射模型的网络误差小,映射结果与实际实验结果的吻合度高,能较为准确地预测复合纤维组成对应制动带的摩擦磨损性能指标,解决了二者关系无法用显函数表征的问题,为制动带无石棉复合纤维组成的优化设计奠定了基础。     

丁腈橡胶对腰果壳油改性酚醛树脂基摩擦材料性能的影响

为使腰果壳油-酚醛树脂基摩擦材料满足重型机械和设备的使用要求,基于干法工艺,采用丁腈橡胶对腰果壳油-酚醛树脂进行共混二次改性,研究不同含量丁腈橡胶对摩擦材料力学性能、耐热性能、摩擦磨损性能的影响。结果表明:丁腈橡胶的加入能够提高摩擦材料的冲击强度,同时降低材料的弹性模量和剪切模量,但随着橡胶含量的增加,摩擦材料的耐热性逐渐下降;丁腈橡胶含量的增加会提升摩擦材料的摩擦因数稳定性并能够保证较高的低温摩擦因数,当橡胶质量分数5%时,摩擦材料表现出最好的抗磨损性能。     

45钢的摩擦磨损特性实验研究

采用自制的销盘式干滑动摩擦磨损试验机,研究了45钢配副的摩擦磨损特性.结果表明:材料的磨损率随着速度、载荷的增加而增大;摩擦系数随着速度、载荷的增加而减小.磨损机理主要为磨粒磨损和粘着磨损.     

Wear and friction behavior of sand cast brake rotor made of A359-20 vol% SiC particle composites sliding against automobile friction material

The effect of load range of 30-100 N and speed range of 3-12 m/s on the wear and friction behavior of sand cast brake rotor made of A359-20 vol% SiC particle composites sliding against automobile friction material was investigated. Dry sliding frictional and wear behavior were investigated in a pin-on-disc type apparatus. Automobile friction material was used as pin, while the A359-20 vol% SiC particle composites formed the rotating disc. For comparison, the wear and friction behavior of commercially used cast iron brake rotor were studied. The results showed that the wear rate of the composite disc decreased with increasing the applied load from 30 to 50 N and increased with increasing the load from 50 to100 N. However, the wear rate of the composite disc decreased with increasing the sliding speed at all levels of load applied in the present work. For all sliding speeds, the friction coefficient of the composite disc decreased with applied load. The worn surfaces as well as wear debris were studied using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyzer and X-ray diffraction (XRD) technique. At load of 50 N and speed range of 3-12 m/s, the worn surface of the composite disc showed a dark adherent layer, which mostly consisted of constituents of the friction material. This layer acted as a protective coating and lubricant, resulting in an improvement in the wear resistance of the composite.     

一种轿车摩擦材料配方的优化方法

为快速优化出摩擦材料的配方,利用均匀设计方法设计配方优化试验,按照国标GB5763—2008规定测定所制备材料的摩擦因数和磨损率,经过综合评价后获得摩擦因数稳定性参数、摩擦因数偏移系数、综合磨损率作为均匀设计试验的3组结果。利用SAS统计分析软件,通过编写计算程序,分别求出3个二次回归模型。再将3个模型合成为一个摩擦磨损性能综合分析模型,用MatLab软件经编程获得最佳配方。结果表明:用此方法优化后摩擦材料的摩擦因数稳定,与指定摩擦因数接近,磨损率明显降低。     

高速列车制动片摩擦块尺寸对制动噪声特性的影响

同一工况下,在制动摩擦噪声试验机上使用3种不同尺寸的圆形摩擦块进行制动摩擦噪声对比试验,通过对不同摩擦块尺寸状态下的界面噪声信号进行等效声压级分析和频谱分析,研究摩擦块尺寸对制动噪声特性的影响;对界面磨损形貌采用光学显微镜和二维轮廓仪进行分析,并计算出摩擦界面上的摩擦弧长,以揭示摩擦块尺寸对制动噪声行为的影响机制。结果表明:在试验条件下,摩擦面积相同时,大圆形摩擦块能有效地抑制制动噪声,而中圆形和小圆形摩擦块的制动噪声强度较大;相较于大圆形摩擦块,中圆形和小圆形摩擦块表面出现明显犁沟和剥落等"不平顺"磨损因素会造成高强度的尖叫噪声;大圆形摩擦块相比于中圆形和小圆形摩擦块的摩擦弧长较短,这也是造成大圆形摩擦块状态下制动噪声强度减弱的一个重要因素。