弓网接触界面热效应与磨损量的数值模拟

在高速/强电流作用下,弓网接触界面摩擦磨损程度的量化是衡量弓网系统电能传输稳定性的重要技术指标。分析影响弓网接触界面磨损量的电流、速度、接触压力等定量因素,在COMSOL Multiphysics软件环境下,对这三个因素造成的弓网接触界面温度变化进行量化,间接反映滑动接触界面的摩擦磨损程度。运用该方法所得的数值模拟结果与试验分析的结果是一致的。     

温度对受电弓滑板材料磨损的影响

在销-盘试验机上试验研究温度对受电弓滑板材料摩擦磨损的影响,探索在各种温度下弓网系统的摩擦磨损性能。试验结果发现,温度是影响弓网系统摩擦因数和磨损量的主要因素之一。干态摩擦时,摩擦因数随着试验温度的升高而增大。磨痕的SEM和EDS分析显示,温度较低的情况下,摩擦表面有大量的犁沟和磨粒,主要以磨粒磨损为主,对应的磨损量比较少。高温时,摩擦表面有氧化、熔融的特征,主要以黏着磨损为主,对应的磨损量比较大。     

架空导线的摩擦磨损研究进展

概述了架空导线摩擦磨损行为的研究与应用现状,分析了其产生原理及摩擦磨损过程,综述了国内外对架空导线的摩擦与磨损机制的研究现状,并指出了目前研究的缺陷以及今后需要重点研究的方向.     

弓网振幅对纯碳及浸金属碳滑板载流摩擦磨损性能的影响

应用环-块式摩擦磨损试验机研究不同弓网振动幅值下纯碳/铜合金和浸金属碳/铜合金2种摩擦副的载流摩擦磨损行为。试验结果表明：弓网之间在不间断地发生近似正弦规律的振动,2种摩擦副的电弧功率都随着振动幅值的增大呈现先增大后减小的趋势,纯碳滑块更容易发生起弧现象,电弧功率更大;2种摩擦副的摩擦因数都随着振动幅值的增大而减小,浸金属碳有更好的耐磨性。使用扫描电镜对滑块的磨损形貌进行观察,结果表明：在一定范围内,随着振动幅值的增大,电弧对纯碳和浸金属碳2种滑块材料的烧蚀程度均加剧;纯碳滑块电弧侵蚀的表现形式为烧蚀坑和热应力裂纹,浸金属碳滑块电弧侵蚀的表现形式为犁沟、材料剥离和烧蚀麻点。     

地铁刚性弓网系统接触线磨损特性试验研究

为研究地铁刚性接触网系统接触线磨损的规律,以地铁刚性接触网系统常用的浸金属碳滑板/铜银合金接触线作为摩擦副,通过模拟地铁弓网系统运行参数,使用载流摩擦磨损试验机研究有、无电火花放电情况下,浸金属碳滑板与铜银合金接触线直流电滑动过程中磨损量、摩擦因数、载流效率随滑动距离的变化。试验结果表明：电火花放电会使得接触线与浸金属碳滑板磨损量显著上升,出现电火花放电时摩擦因数较小,弓网系统载流效率会明显降低同时出现大幅波动。试验后对碳滑板和接触线表面形貌的观察可知：电火花放电会使得浸金属碳滑板表面烧蚀坑数量和尺寸大小增加,同时会出现滑板材料大面积剥落和表面裂纹增多的问题,接触线表面形貌变得更加粗糙。     

降低弓网磨耗的受电弓主动控制策略研究

为了减少受电弓与接触网的磨耗,延长弓网使用寿命,同时保证弓网受流质量,在载流摩擦磨损理论、控制理论和微控制技术基础上,提出一种基于接触网磨损量检测和弓网接触压力受控的受电弓主动控制策略,并从软件方面对控制系统受到的电磁干扰进行防护设计。受电弓采用该主动控制策略,能明显降低弓网的磨损量,有效控制弓网接触压力的波动,提高和改善高速机车的受流质量。     

纤维方向对C/SiC复合材料摩擦学特性的影响

以不同纤维方向C/SiC复合材料分别与氧化铝增韧的氧化锆陶瓷(Al_2O_3-ZrO_2)及调质处理的45~#钢组成摩擦副进行销-盘摩擦实验,研究对摩副材料及纤维方向对摩擦副摩擦磨损性能及磨损机制的影响。结果表明,C/SiC复合材料与Al_2O_3-ZrO_2和45~#钢摩擦时,其垂直纤维叠层方向的摩擦磨损性能均优于平行纤维叠层方向,且垂直纤维叠层方向C/SiC复合材料与Al_2O_3-ZrO_2摩擦副具有最小的摩擦因数和磨损率,摩擦过程更稳定;纤维C/SiC复合材料与Al_2O_3-ZrO_2陶瓷和45~#钢摩擦副的磨损形式主要均为磨粒磨损,与45~#钢摩擦时还伴随着化学磨损。     

表面粗糙度对滑动电接触磨损率的影响

在电气化铁路弓网系统中,磨损率是衡量列车运行状态与接触导线使用状态的重要指标。为了充分模拟弓网系统中磨损率情况,利用自行搭建的滑动电接触摩擦磨损试验机对滑板和接触导线进行摩擦磨损试验,分析滑板表面粗糙度、法向压力、接触电流与运行速度对磨损率的影响。得出结论:滑板磨损率随滑板初始表面粗糙度、接触电流、法向压力、运行速度的增加而增加,而高载荷下粗糙度对于磨损率的影响降低;滑板摩擦从磨合期进入稳定摩擦期存在一个临界表面粗糙度,当滑板初始表面粗糙度值等于临界粗糙度值时,其磨损率最低;不同初始表面粗糙度的滑板在跑合期内磨损过程不同,在稳定摩擦期内磨损过程趋于一致,且摩擦试验后滑板表面粗糙度也接近。     

摩擦磨损自修复润滑油添加剂研究进展

阐述了摩擦磨损自修复润滑油添加剂的研究现状,归纳为软金属自修复添加剂、自补偿修复添加剂和矿物微粉自修复添加剂3类主要的研究内容。对今后的研究方向进行了展望,指出了摩擦磨损自修复添加剂的发展方向及思路。     

干摩擦条件下WC-Ni/SiC摩擦副的摩擦磨损性能研究

在MMU-10屏显式材料端面摩擦磨损试验机上采用环-环接触摩擦方式,研究了WC-Ni硬质合金与SiC陶瓷材料异配对摩擦副在干摩擦条件下的摩擦磨损性能,并与WC-Ni/WC-Ni硬质合金自配对摩擦副的摩擦磨损性能进行对比.利用扫描电子显微镜与能谱仪对摩擦副的磨损表面进行了观察和分析.结果表明:在相同试验条件下,对比WC-Ni/WC-Ni硬质合金自配对摩擦副,WC-Ni/ SiC摩擦副的摩擦因数稍低点;WC-Ni/ SiC摩擦副的磨损机制主要为磨粒磨损,而WC-Ni/WC-Ni摩擦副磨损机制为粘着磨损兼氧化磨损;由于WC-Ni/WC-Ni摩擦副的磨损表面发生氧化反应和焊合效应,配对效果劣于WC-Ni/ SiC摩擦副.     

Study of the Tribotechnical Properties of a Cutting Tool Made of Sintered Powder Tool Materials

The research results on the wear of cutting tools made by sintering high-speed steel powders have been presented. It has been shown that powder tool materials based on high-speed steel additionally alloyed with titanium carbide have high wear resistance and can be classified as a new class of self-organized tool materials. As has been shown by the research, the wear resistance of these tools is 2–3.5 times higher than the wear resistance of standard high-speed steel tools.     

Wear by paper and ribbon

A wear apparatus developed by Roshon was used to investigate the nature of wear produced by paper and printer ribbon. The characteristics of the wear produced by these materials on hardened steel were studied and compared with the characteristics of wear produced by abrasive and adhesive wear mechanisms. The wear was also compared with a simulated abrasive situation using a mixture of Al₂O₃ powder and oil on a fabric surface. It was concluded that the wear processes of paper and ribbon are similar and primarily abrasive. Small quantities of hard micron-size and submicron-size particles in these materials were identified as the cause of this abrasive wear. In addition, the influence of such test parameters as load, speed, temperature and humidity on wear was also investigated. Recommendations regarding test conditions to establish the abrasiveness of these materials were developed.     

气氛环境下材料摩擦磨损行为研究进展

综述了国内外近年来气氛苛刻环境条件下材料摩擦磨损行为研究成果,总结了金属及合金材料、复合材料、陶瓷材料、涂层材料等在气氛环境下的摩擦学性能及磨损机制,阐述了气氛环境材料磨损机制分析方法,提出了研究中存在的问题和今后的研究方向.     

Friction and wear of a Zr-based amorphous metal alloy under dry and lubricated conditions

The unusual internal structure of amorphous metals has been of interest to the tribology community for several decades, but most of the research on these materials has involved unlubricated experiments or tests in other than ambient air environments. If the suitability of amorphous metals is to be evaluated for engineering applications, a great deal more research is needed to assess their behavior under liquid lubricated conditions. Studies in the early 1980s focused on Fe---Co---B---Si compositions. The results reported here focus on an alloy system based on zirconium. Pin-on-disk tests were performed both dry and with diesel oil lubrication. The disks were composed of polished SAE 52 100 steel, and pin specimens of type 303 stainless steel, commercially-pure nickel (Ni-200), and an amorphous alloy of Zr---Cu---Ni---Ti---Al were used. The amorphous alloy was the hardest of the three pin materials. Friction coefficients and wear rates were measured under a limited set of conditions. Under dry conditions, the amorphous metal alloy performed comparably or slightly better than the other two pin materials, but under lubricated conditions, it had the highest friction coefficient and highest wear rate of the three combinations. Differences in the ratios of dry to lubricated wear rates for the three material combinations are discussed in terms of the compatibility of non-ferrous materials with current engine lubricants. Observations on the nature of amorphous alloy wear particles are linked to a combination of simultaneously occurring wear processes. No sliding-induced transformations were detected by X-ray methods.     

载流摩擦磨损研究进展

载流摩擦磨损是摩擦副在有电流通过时的接触行为。载流摩擦副在工作过程中受力、电、热等多种因素耦合作用,损伤机制复杂多变。综述载流摩擦中的摩擦磨损机制,重点分析服役工况对载流摩擦磨损性能和导电性能的影响,阐述电弧产生的原因及影响因素,并对载流摩擦中的温度场及其仿真模拟研究成果进行归纳,总结载流摩擦材料的应用现状。概括载流摩擦的研究现状及其存在的问题,并指出未来应加强接触副材料在多环境下、多因素耦合作用下的摩擦磨损行为和失效机制研究,并有针对性地研发新型复合材料,以满足具体的工作条件和特殊的性能要求。     

海洋环境下典型金属材料腐蚀与磨损研究进展

海洋环境下金属材料的腐蚀与磨损及其复杂的交互作用是影响海洋装备可靠性和工作效率的关键因素。在概述海洋环境下金属材料腐蚀和磨损的现象及问题的基础上,分析海洋环境下典型金属腐蚀与磨损的交互作用研究进展及发展趋势,并对不锈钢、钛合金与铝合金等主要海洋环境用金属材料在不同介质下的腐蚀与磨损问题进行探讨,重点阐述海洋环境下金属腐蚀与磨损中相互促进的正交互作用和相互抑制的负交互作用机制以及它们之间的相互影响、过渡和转换等方面的研究进展。在腐蚀与磨损正、负交互作用转变的过程中,从微观角度讲,奥氏体和马氏体相的多次转变是主要影响因素;而从宏观角度看,材料的摩擦因数、载荷、运动形式等动摩擦因素和Cl-浓度、pH值、频率及外加电位等电化学因素是两类主要影响因素。对比分析多种腐蚀与磨损交互作用的计算模型,阐述利用表面技术改善金属材料防腐耐磨性能的研究进展,提出金属材料腐蚀与磨损的负交互作用机制、微生物对腐蚀与磨损交互作用的影响机制、微动磨损与腐蚀的交互作用研究以及腐蚀与磨损交互作用量的准确量化是未来的研究重点。     

Review of research work in sinking EDM and WEDM on metal matrix composite materials

Metal matrix composites (MMCs) are newly advanced materials having the properties of light weight, high specific strength, good wear resistance and a low thermal expansion coefficient. These materials are extensively used in industry. Greater hardness and reinforcement makes it difficult to machine using traditional techniques, which has impeded the development of MMCs. The use of traditional machinery to machine hard composite materials causes serious tool wear due to the abrasive nature of reinforcement. These materials can be machined by many non-traditional methods like water jet and laser cutting but these processes are limited to linear cutting only. Electrical discharge machining (EDM) shows higher capability for cutting complex shapes with high precision for these materials. The paper presents a review of EDM process and year wise research work done in EDM on MMCs. The paper also discusses the future trend of research work in the same area.     

Materials selection to excavator teeth in mining industry

Hard alloys are normally used as materials for excavators teeth in mining industry. In most cases these alloys do not have enough anti-wear properties and coatings are employed as a good alternative. The objective of this work is to test the abrasive wear resistance of several cast irons alloyed with different elements. Laboratory tests based on the ASTM G105-89 standard were compared to tests carried out under real working conditions of excavator teeth in mines.

The experimental results show an acceptable correspondence between laboratory and field tests. To complete the laboratory research, hardness and microhardness measurements and optical micrographs were performed to identify the mechanism of wear. As a result of the experimental work, an economic evaluation of materials was also performed.     

Wear of commercially available plastic materials

This article reviews the data on the wear of commercially available plastic-based bearing materials. Much of these data were obtained during the course of a six-year project at NCT, using a purpose-built test facility. The wear performance of materials has been assessed in terms of the effect of bearing pressure and surface temperature rather than PV factors. Basic wear data are presented on a wide range of materials. The effect of bearing pressure on the wear rate of some composite materials is discussed and the influence of wear debris removal on the wear rate at high loads is also assessed. The wear performance of filled-ptfe composites and polyimides at elevated temperatures is compared. These tribological data are presented in a form which is intended to enable designers to select appropriate materials and to estimate bearing life under the conditions of a particular application     

关节轴承磨损性能试验研究进展

总结了关节轴承的磨损性能试验以及摩擦磨损试验机的研究进展。影响关节轴承摩擦磨损性能的主要因素为载荷、摆频、摆动角度、温度、轴承材料和自润滑材料材质及含量,并根据已有的研究工作对将来试验机的发展趋势提出了一些看法。