不同湿度环境中钢/铜配副摩擦磨损性能研究

应用QG-700型高温气氛摩擦磨损试验机研究了CrNiMo钢/黄铜配副在不同环境湿度条件下的滑动摩擦磨损性能,利用三维形貌轮廓仪、EDAX能谱分析仪(EDS)分析了其磨损机制。结果表明:随着环境气氛湿度的增加,配副的摩擦因数、销/盘试样磨损率和摩擦温度均呈降低趋势,摩擦学性能得到改善。销试样的磨损机制主要为黏着磨损,环境湿度的增大弱化了配副材料的黏着磨损。     

永磁场条件下45钢与GCr15钢摩擦磨损性能试验研究

基于HSR-2M高速往复摩擦磨损试验机,研究在永磁体磁场条件下滑动速度、载荷等参数对45#钢/GCr15钢摩擦副摩擦学性能的影响,通过磨痕形貌分析其磨损机制,并与无磁场条件下的试验结果进行对比。试验结果表明:磁场的引入可以在一定程度上减小摩擦因数和降低磨损率,证明磁场能够改善45#钢/GCr15钢摩擦副的摩擦学性能;增大滑动速度将降低摩擦因数和磨损率,增大载荷将降低摩擦因数,增加磨损率。无磁场时,摩擦副的摩擦磨损为典型的磨粒磨损,磨损系统的磨损率和摩擦因数较大;有磁场时,磨损形式主要为黏着磨损,摩擦因数和磨损率较小。     

表面粗糙度对黄铜/铬青铜摩擦副载流摩擦磨损性能影响的研究

以黄铜/铬青铜为摩擦副,在销-盘式摩擦磨损试验机上进行了载流摩擦学特性研究,探讨了载流条件下摩擦副的表面粗糙度对摩擦学特性的影响.结果表明:摩擦副表面粗糙度存在一个最佳值,使质量磨损率最小,载流效率、载流稳定性也较好;摩擦因数先随表面粗糙度的降低而升高,当表面粗糙度降低到一定程度以后摩擦因数的变化趋于平稳.质量磨损率随着表面粗糙度的降低先减小后增大;载流导致质量磨损率增大,且随着电流密度的增大,这种影响更加显著.     

受流条件下碳碳复合材料的摩擦学特性研究

以碳碳复合材料和铬青铜作为配副,研究了受流条件下碳碳复合材料的摩擦学特性.结果表明:速度、载荷和电流是影响受流条件下碳碳复合材料摩擦学特性的重要因素.在电流一定的条件下,碳碳复合材料的摩擦因数和磨损率随速度的增大而增大;摩擦因数随载荷的增加而增大,而磨损率随载荷的增加而减小.在载荷一定条件下,随着电流的增加,碳碳复合材料的摩擦因数减小而磨损率增大.与一般条件下的摩擦学特性相比较,碳碳复合材料在受流条件下的摩擦因数明显降低,而磨损率却明显提高.     

稀土化合物改性复合材料在油润滑下的摩擦学性能

以竹纤维为增强相,通过稀土化合物改性制备一种树脂基复合材料;采用环块式摩擦磨损实验,研究稀土化合物改性复合材料在油润滑状态下载荷、转速对试样摩擦学性能的影响,以及稀土化合物改性对复合材料试样摩擦学性能的影响;比较干摩擦状态和油润滑状态下复合材料的摩擦学性能,观察和分析试样磨损表面形貌,探讨其磨损机制。实验结果表明:油润滑条件下,稀土化合物改性复合材料的摩擦因数和磨损率都随着载荷的增大而增加;较高载荷下摩擦因数随着转速的增大先增加后减小,而磨损率则呈现逐步增加的趋势;稀土化合物的改性使竹纤维和基体界面结合更为紧密,提高摩擦因数的同时降低了磨损率;在油润滑作用下,试样磨损由干摩擦时的磨粒磨损和疲劳磨损转变成为轻微的疲劳磨损;在油润滑状态下,复合材料处于边界润滑状态,故摩擦因数和磨损率均低于干摩擦。     

磁场条件下钢轨材料的摩擦磨损性能试验研究

基于HSR-2M高速往复摩擦磨损试验机,试验研究在永磁体磁场条件下,法向载荷、往复速度等参数对钢轨材料摩擦性能的影响,通过磨痕形貌分析其磨损机制,并与无磁场条件下的结果进行对比。试验结果表明:磁场的引入可以在一定程度上减小钢轨材料的摩擦因数、磨损率;增大滑动速度对摩擦因数和磨损率均有减小作用,增大载荷能够降低摩擦因数,但磨损率增加;磁场能够提高钢轨材料在摩擦过程中的磨损性能。无磁场时,钢轨材料磨损形式为典型的磨粒磨损,摩擦系统的磨损率和摩擦因数较大;有磁场时,磨损形式主要为黏着磨损,摩擦因数和磨损率较小。     

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。     

烧结压力对铜基粉末冶金闸片材料摩擦学性能的影响

在不同烧结压力下制备了铜基粉末冶金闸片材料,研究了烧结压力对其孔隙率和硬度的影响;采用高速摩擦磨损试验机,选择15CrMo钢作为配副材料,研究了铜基粉末冶金闸片材料的摩擦学特性,并用扫描电镜观察分析了材料显微组织及磨损表面形貌。结果表明:随着烧结压力从0 MPa增大到1.25 MPa,试验材料的孔隙率降低而硬度得到提高,摩擦因数和磨损率都同步减小;再继续增大烧结压力对孔隙率和摩擦磨损性能的影响不大。     

玻璃和碳纤维含量对树脂基摩擦材料摩擦学性能的影响

采用腰果壳油改性酚醛树脂为基体,添加不同比例的碳纤维和玻璃纤维,利用热压烧结的方式制成摩擦材料。利用环-块摩擦磨损实验机与高速钢配副研究摩擦材料在不同制动条件下的摩擦学性能。研究结果表明:碳纤维和玻璃纤维的总量一定时,随着玻璃纤维的含量增加,摩擦材料的摩擦因数随之增大;而相应的磨损率先减少后增大;在摩擦过程中,摩擦材料极易在磨损表面形成一层致密的摩擦膜,摩擦膜的产生降低了摩擦材料的摩擦因数和磨损率,且在高速条件下,摩擦膜更容易形成;当玻璃纤维和碳纤维的质量分数分别为8%、9%时,摩擦材料表现出最好的摩擦学性能;玻璃和碳纤维填充摩擦材料的磨损机制主要为黏着磨损。     

高温氧气条件下CrNiMo钢的摩擦磨损特性研究

以CrNiMo钢和H96黄铜组成配副,利用QG-700型高温气氛摩擦磨损试验机,研究了高温氧气气氛环境中滑动速度、接触压力等对CrNiMo钢摩擦学特性的影响.采用扫描电子显微镜(SEM)和能谱仪(EDS)对磨损表面进行表征.结果表明:在高温氧气气氛中,随着滑动速度和接触压力的增大,摩擦因数逐渐减小,磨损率逐渐增大.在滑动速度和接触压力逐渐增大的过程中,CrNiMo钢的主要磨损机制由粘着磨损转变为氧化磨损.     

MoDTC增强型磁性液体减摩性能试验研究

为提高磁性液体的减摩性能，在现有Fe3O4磁性液体的基础上，通过微量添加二烷基二硫代氨基甲酸钼（MoDTC），制备一种MoDTC增强型磁性液体。对MoDTC增强型磁性液体微观粒子的结构、组成成分、磁性能进行测试分析，在不同载荷、速度条件下进行摩擦磨损试验，探究MoDTC含量对磁性液体摩擦磨损性能的影响。实验结果表明：MoDTC增强型磁性液体比铁磁性液体饱和磁化强度小，且剩磁几乎为0，具有较好的磁性能；在试验研究范围内，Fe3O4磁性液体润滑下的摩擦因数比油润滑低，MoDTC增强型磁性液体的摩擦因数低于Fe3O4磁性液体的摩擦因数，且MoDTC质量分数为6%时减摩效果较佳；当载荷在25~45 N范围内，MoDTC增强型磁性液体的摩擦因数先随载荷增大而减小，超过临界值30 N后，摩擦因数随载荷增大而增大。研究结果表明，磁性液体中加入适量的MoDTC具有较好的减摩性能，能在一定程度上改善磁性液体的润滑性能。     

Wear and Friction Characteristics of Magnetorheological Fluid under Magnetic Field Activation

In this article, wear and friction characteristics of a magnetorheological (MR) fluid were studied under different magnetic fields. Using a pin-on-disc tribometer, the wear loss and friction coefficient were obtained with and without a magnetic field. The friction and wear of three typical materials under magnetic field were investigated at various normal loads and rotating speeds. After the wear tests, the worn surfaces of specimens were observed using a scanning electron microscope (SEM) in order to investigate the wear mechanisms, and the contacting surfaces were analyzed by energy-dispersive X-ray spectroscopy (EDS) to investigate the variation of elemental composition on the worn surface. Test results showed that the MR fluid exhibits better tribological characteristics under a magnetic field compared to the case without a magnetic field. The general morphology of the MR particles and wear debris was observed to assist with the analysis of friction and wear. The SEM micrographs and EDS spectra of the worn surfaces showed that the predominant wear mechanism in the case of the steel and brass specimens was abrasive wear by asperities and MR particles on the worn surfaces, whereas a mixed wear mechanism that included adhesive wear and abrasive wear was observed in the case of the aluminum specimen.     

直流磁场下销盘摩擦副接触面的磁感应强度和磁吸力分析

为了研究磁场对材料摩擦磨损性能的影响,通过试验检测了销盘接触时的磁吸力,利用电磁场有限元软件分析计算了销盘摩擦副在接触区域的磁感应强度大小和分布及磁吸力的大小。试验和仿真结果表明:磁感应强度和磁吸力都随线圈电流的增大和气隙的缩小而增大,并且与材料的磁化特性有关;销盘上的磁场分布不均匀,当盘旋转进行摩擦磨损试验时,盘上各点将产生动态磁化现象;由于销和盘之间的微凸峰接触存在漏磁,故在磁场仿真时可用一个极小的间隙来表示其实际磁接触状态;在销和盘接触时,可用试验得到的最大磁吸力值根据麦克斯韦公式计算出接触面的平均磁感应强度。     

Research on tribo-magnetization phenomenon of ferromagnetic materials under dry reciprocating sliding

In order to reveal tribo-magnetization phenomenon of ferromagnetic materials, a new apparatus which involved reciprocating friction tests of pin-on-block type under the geomagnetic field has been built to perform the tests. Based on the changes of the surface magnetic field of wear scar and the macroscopic and SEM analyses, it is concluded that tribo-magnetization of ferromagnetic materials is a two-stage process and the demarcation point of these two stages is the transition point of the friction forms. Furthermore, the shape and the position of wear scar can be estimated through measuring the surface magnetic field of wear scar.     

Magnetic fluids in sealing and lubrication – a state of the art review

The paper is a review of the properties and functions of magnetic fluids and their potential use in tribological applications, such as seals and bearings. They offer new possibilities for achieving low friction, low wear, and no leak- age. Magnetic fluids or ferrofluids consist of magnetic particles suspended in a carrier fluid and a coating on the particles. The coating prevents the agglomeration of the particles through magnetic and molecular attraction by keeping the distance between them sufficiently large. The magnetic fluids have the basic properties of liquids and they act like ferromagnetic materials in the presence of an external magnetic field. Shaft sealing is the most promising potential application for ferrofluids. Magnetic seals have zero-leakage and low friction, they are non-stick and they have high-performance properties. Lubrication is another important application of ferrofluids. The advantage over conventional lubricants is the possibility of keeping the lubricant exactly and only where it is needed. They provide the possibility of increasing the life of components. Furthermore, because they do not contaminate, ferrofluids are also used as lubricants in clean environments.     

Effect of Temperature and Relative Humidity on Friction and Wear Properties of Silicone-Based Magnetorheological Elastomer

In this study, the effect of varying temperature and humidity on the friction and wear properties of a silicone-based isotropic magnetorheological (MR) elastomer were examined with an applied magnetic field. Specifically, MR elastomer specimens were fabricated, and a temperature- and humidity-adjustable reciprocating friction tester was employed. The results indicated that the friction coefficient decreased across all tests when a magnetic field was applied. The friction coefficient increased when the temperature increased and slightly decreased following an increase in relative humidity. The wear depth results also exhibited an increasing pattern as the temperature increased and a decreasing pattern when the relative humidity increased. The surface state experienced significant changes under varying temperatures and relative humidity conditions with and without a magnetic field.     

Effect of Magnetic Oxidation and Surface Carbon Distribution on Friction and Wear Characteristics of 45 Steel under the DC Magnetic Field

Abstract

The sliding dry friction behaviors and wear properties of normalized 45 steel and annealed 45 steel under different magnetic field intensities were experimentally studied using a self-made HY-100 pin–disc friction and wear tester. The influence of a magnetic field on the friction and wear of 45 steel were also investigated by analyzing the microscopic friction surface and subsurface using a 3D shape analyzer and metallographic microscope. The experimental results show that the friction coefficient of the normalized 45 steel was greater than that of the annealed 45 steel under magnetic field. In addition, the results illustrate that the external magnetic field can effectively improve the wear performance of carbon steel. The wear rate of normalized 45 steel was lower than that of annealed 45 steel. The wear performance of normalized 45 steel was more significantly improved compared to annealed 45 steel with a magnetic field. Energy spectrum analysis indicated that the effect of the magnetic field on the degree of friction and oxidative wear of the normalized 45 steel was weaker than that of the annealed 45 steel, and the ratio of oxygen to iron and the oxidation area on the friction surface of the normalized 45 steel were smaller. It is believed that as an oxidation protectant, carbon reduces the oxidation wear of 45 steel. The carbon on the normalized 45 steel surface was uniformly distributed and the protective effect of friction surface was better. Therefore, the oxidation wear and oxide shedding were reduced and the wear performance was improved.     

Magnetoelastic Stability of Magnetic Axial Bearings

Permanent magnet bearings offer no wear and no mechanical friction. Recently, Rare Earth (RE) permanent magnets have been used, which give rise to force fields 20 times greater than those of common magnets. RE also allows to build magnets suitable for bearings of every shape. RE bearings are then profitable. On the other hand, permanent magnet bearings are unstable. For example, the levitated ring of the axial bearing with opposite magnetic fields of Fig. 1 is stable axially, but unstable radially. It has been, however, verified that a permanent magnet system may become stable under peculiar conditions. As an example, if the above-mentioned levitated ring is subjected to a parametric axial excitation, its radial instability can be removed. In our opinion, it may also be possible that stability is obtained by exploiting microstructural properties of ferromagnetic materials, especially of RE, like dimensional and magnetic changes if subjected to mechanical stresses. Then, in this paper, the stability of the levitated member of an RE axial ring bearing is investigated by a suitable exploitation of magnetoelastic properties of the ring.

微米Wp/Cu基复合材料耐磨行为

以微米级的钨粉和铜粉为原料,采用冷压烧结方法制备出Wp/Cu基复合材料,并进行了热挤压加工,考察了该材料的耐磨行为。结果表明:该复合材料不仅具有良好的抗磨性能,而且适宜同40Cr钢组成在油润滑条件下工作的摩擦副;在油润滑条件下,其磨损体积损失仅是QSn6.5-0.4的11.6%,磨损表面呈Cu基体、凸出Wp和少量孔隙的耐磨组织,并且未发现来自40Cr钢的转移物。     

干摩擦机械密封端面材料配对性能的台架试验研究

为了研究密封端面材料配对对干摩擦机械密封性能的影响,使用自主设计研发的干摩擦机械密封试验系统,选择浸锑石墨、浸树脂石墨,分别与38CrMoAlA(不喷涂)、38CrMoAlA(表面喷涂Cr 2O 3)、40CrNiMoA(表面喷涂Cr 2O 3)3种典型的材料配对进行干摩擦和磨损试验,并对端面温升、磨损率、摩擦功耗和泄漏率等试验结果进行对比分析。结果表明:在干摩擦状态下,对于不同材料配对,摩擦磨损规律显示出了多元性;在6组端面配对中,浸锑石墨与38CrMoAlA(表面喷涂Cr 2O 3)配对性能最佳,浸金属石墨更适用于极端工况,摩擦磨损性能更佳,但浸树脂石墨材料密封性能更好,泄漏率更小;动环表面喷涂材料可有效提高动环表明硬度,优化表面结构,改善动环摩擦磨损性能和密封性能;动环基体材料对配对性能影响不可忽视,导热效果好、线膨胀系数低的材料可降低端面温度。