氮离子注入浓度对弹条钢基体Cr/CrSiN复合涂层的摩擦学性能影响研究

在轨道用扣件弹条钢(60Si2Cr)上注入不同浓度的氮离子,用电弧离子镀技术沉积了Cr过渡层,并在其上制备了CrSiN/Cr复合涂层。在UMT-3多功能摩擦磨损机上对复合层进行了法向载荷为20N的摩擦磨损实验,探讨了经不同氮离子注入浓度后Cr/CrSiN复合涂层摩擦磨损行为和损伤机理,研究发现,经氮离子注入后,复合涂层表面硬度明显的增加,随着离子注入浓度的升高涂层的耐磨性逐渐提高,其磨损机制主要为剥落和磨粒磨损。     

玻璃纤维增强聚醚醚酮复合材料在水润滑下的摩擦学性能

利用球盘式摩擦磨损试验机考察了玻璃纤维(GF)增强聚醚醚酮(PEEK)复合材料在干摩擦和水润滑条件下的摩擦磨损性能,并探讨了其磨损机理。结果表明:在干摩擦和水润滑条件下,PEEK和GF/PEEK的摩擦因数和磨损率均随载荷和对磨时间的增加逐渐增大并趋于稳定,GF的加入可以显著降低GF/PEEK复合材料的摩擦因数和磨损率;在水润滑条件下,PEEK和GF/PEEK的摩擦因数和磨损率比干摩擦下显著降低。干摩擦下,PEEK以黏着磨损和磨粒磨损的混合磨损形式为主,水润滑条件下,磨损方式主要是以轻微的黏着磨损为主;干摩擦下,GF/PEEK磨损表面有大量的微观断裂裂纹和破碎,以磨粒磨损和疲劳磨损为主,水润滑条件下,磨损表面仅有微观切削的痕迹,磨损方式以轻微磨粒磨损为主。由于水的冷却和润滑作用,使得复合材料向对偶钢球的黏着转移明显减弱,同时阻止了对偶钢球上的Fe向复合材料磨损表面转移,从而减轻摩擦、降低摩擦表面温升,显著改善复合材料的摩擦磨损性能。     

面齿轮副齿面磨损动态响应及其典型特征分析EI北大核心CSCD

为了揭示齿面磨损对面齿轮传动的影响,提出了一种结合黏着磨损公式的面齿轮副齿面接触分析方法。通过齿面接触分析得到面齿轮副接触椭圆离散点上的相对位移及接触应力,再根据黏着磨损公式可以定量得到齿轮的磨损深度;编写了含磨损的面齿轮副齿面坐标,并在ABAQUS软件中计算了不同磨损下系统的啮合刚度;将齿面磨损等效为齿面偏差,讨论了不同磨损对静态传递误差的影响;对比了面齿轮副在正常和磨损时的动态响应,分析了转矩对磨损的影响。结果表明:齿面磨损主要影响啮合刚度和静态传递误差的幅值,并且会导致加速度与啮合力幅值的快速增长;转矩的增大会引起磨损加重;相比于无量纲统计指标,加速度均方根对于磨损故障更敏感。     

冷水水表耐久性试验失效现象及原因分析

论述了冷水水表耐久性试验可能出现的失效现象,包括顶尖头磨损、滤水网缠有脏物和塑料丝等杂质、上顶尖头磨损、防反向流截止阀断裂,并进行了原因分析。     

WC-Al_2O_3复合材料摩擦磨损性能

在HT-1000型高温摩擦磨损实验仪上采用球面接触形式对WC-Al_2O_3复合材料进行滑动摩擦磨损实验,研究了WC-Al_2O_3复合材料从常温25℃到600℃温度条件下的摩擦磨损特性,并与WC-6Co进行对比。采用SEM、超景深显微镜及XRD对磨痕表面微观形貌及物相进行观察和分析。结果表明,在常温时,WC-Al_2O_3复合材料的摩擦系数较小,摩擦磨损性能较好。当温度升至600℃时,WC-Al_2O_3复合材料磨痕表面逐渐有氧化物生成,摩擦系数减小,磨损机制由低温下的磨粒磨损为主转化为氧化磨损,WC-Al_2O_3复合材料摩擦磨损性能较差。     

聚醚醚酮摩擦磨损行为和机理的研究

本工作通过摩擦过程中聚醚醚酮(PEEK)结构(包括材料与磨屑结构)的变化研究了PEEK的摩擦磨损机理。结果表明,低负载下,材料的摩擦表面不熔融,但表层的凝聚态结构发生了变化,摩擦状态不变,磨损是由于摩擦对偶的连续作用下产生疲劳而脱落。高负载下,材料表面熔融并发生氧化交联,摩擦状态改变,材料外形结构与内层凝集态结构发生变化,磨损是熔融了的表面层粘附于对偶上经进一步的交联反应后,受剪切力作用而脱落。材料在摩擦磨损过程中的表面状态决定了其摩擦磨损机理,并导致了材料摩擦磨损行为对负载的特殊依赖性。     

C/C复合材料的摩擦转变和磨损机理

总结了国内外各种解释C/C复合材料摩擦磨损转变的观点,C/C复合材料摩擦磨损转变归因于摩擦膜的变化、水和氧的解吸附、磨屑氧化和应力集中四大原因.归纳了不同刹车条件下C/C复合材料的磨损机理,并指出国内关于C/C复合材料摩擦磨损的研究主要集中在摩擦后磨屑和摩擦膜的"静态"观察上,提出了进一步研究应关注"动态"磨损过程.     

活塞式压缩机气缸壁Ni-P刷镀层的耐磨损性能

活塞式压缩机气缸壁磨损严重,为此,分析了磨损过程中磨粒对活塞式压缩机气缸壁磨损机理,研究了对活塞式压缩机气缸壁电刷镀Ni-P层的工艺,并进行了耐磨对比试验.结果表明,在相同条件下,活塞式压缩机气缸壁Ni-P镀层能在很大程度上提高活塞式压缩机气缸壁的使用寿命.     

汽车发动机汽缸磨损诊断及检验措施

发动机的磨损是不均匀的。从汽缸的纵断面来看，磨损一般是上大下小。这种上大下小的磨损俗称为汽缸的“锥形”磨损，在特殊情况下，有的则类似“腰鼓形”的磨损，从汽缸的横断面来看，磨损会使汽缸市区原来的正圆形，俗称为汽缸“失圆”。     

超音速火焰喷涂氧化铬陶瓷涂层的干滑动摩擦磨损性能

采用箱式电阻炉对超音速火焰喷涂氧化铬陶瓷涂层进行热处理,利用显微硬度计、扫描电子显微镜(SEM)、能谱分析仪(EDS)和摩擦磨损试验机等设备,研究热处理温度对氧化铬涂层室温条件下干摩擦性能的影响,并讨论涂层的磨损机制。结果表明,在实验条件下,500℃热处理涂层的综合耐磨减摩性能最好。热处理未能改变涂层的磨损机制,在10N载荷下,涂层的磨损机制以磨粒磨损为主,并伴有轻微的剥落磨损;而在25N载荷下,涂层的磨损机制则以剥落磨损为主,并伴有磨粒磨损。     

The wear behaviour of oxide ceramics-A Review

The paper reviews the wear behaviour of oxide ceramics. Wear maps are considered and consequently mild and severe wear are defined. Since the use of ceramics in engineering applications require operation in the mild wear regime, the paper concentrates on mild wear mechanisms, but also considers factors which control the transition to severe wear. Within the mild wear regime, the formation of tribofilms are discussed and the manner in which dislocation activity leads to the wear transition is considered. The wear of so-called ceramic nanocomposites, for which no time dependent wear transition has yet been observed, is considered and the reasons for enhanced performance discussed. The role of transformation toughening in zirconia ceramics is considered in detail, and reasons for the generally poor wear response of these materials defined.     

高寒动车组车轮磨耗演变特性及其影响分析

对某线路上运行的高寒动车组车轮磨耗进行长期跟踪测试,得到车轮磨耗演变规律。将实测车轮踏面分别与CHN60轨和60 N轨匹配,分析车轮磨耗对轮轨接触几何关系和接触力学特性的影响。利用多体动力学软件SIMPACK建立车辆动力学仿真模型,研究车轮磨耗过程中车辆动力学性能的演变规律。研究结果表明:车轮踏面磨耗随运行里程呈线性增加趋势,动车和拖车平均磨耗速率分别为0.0434 mm/万千米和0.0398 mm/万千米,且几乎没有轮缘磨耗。等效锥度随运行里程呈前期增长较快后期平缓的非线性特性,且与CHN60匹配时等效锥度明显高于与60 N轨匹配。实测轮轨匹配下的力学特性及动力学性能均略有下降,车辆与60 N轨匹配时体现出更好的服役性能。     

Neuentwicklungen für den Verschleiß‐ und Korrosionsschutz beim Plasma‐Pulver‐Auftragschweißen

New developments for wear an corrosion protection by weld surfacing with plasma transmitted arc process Highly wear‐resistant claddings which contain carbides can be applied by weld surfacing with the PTA process. The use of vanadium carbide prevents undesirable reactions with the matrix material. Thus, highly corrosion‐resistant Fe‐based claddings can be produced for applications in the food and marine industries, and Ni‐based claddings can be applied to components exposed to inorganic acid attack. A combined test is applied for determining the relative effect of corrosion under combined exposure to abrasive wear and corrosion and indicates the primacy of abrasive wear for behaviour in operation.     

Abrasive wear of individual grits in diamond rollers and sticks and its relation to the overall tool wear in dressing operations

Abrasive wear of individual grits in diamond dressing tools during the dressing of abrasive wheels is studied. The wear rate is assessed analytically allowing for mechanical-statistical and temperature characteristics of the grit operation in dressing with rollers and sticks, as well as for the temperature-induced variations of the diamond hardness. A relationship is established between wear of individual grits and that of the diamond-containing layer as a whole.     

On the pretreatment process for the object extraction in color image of wear debris

In this article, some pretreatment techniques used for the object extraction in color debris image were introduced, which was an important basic work in ferrographic technology to identify precisely wear debris produced by friction and wear from the relative motions between machine parts. These pretreatment techniques included image enhancement, image segmentation, filling pore, image erosion, and recognition of wear debris. The results showed that these methods were feasible and effective, which could be applied to extract object of color wear debris image successfully and precisely. It provided an important basis for the recognition technique of wear debris which was related to monitoring machine operation state and fault diagnosis. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 277–284, 2007     

Numerical study on the abrasive wear of screw flights considering the scaffolding near the bustle pipe zone in a COREX shaft furnace

Scaffolding near the bustle pipe zone is a common problem in the operation of the COREX shaft furnace. To study the asymmetrical abrasive wear of screw flights in the presence of scaffolding, a three-dimensional COREX shaft furnace model with two representative locations of scaffolding is established based on the Discrete Element Method. Two different structures of the screw are investigated and the abrasive wear is calculated using Archard wear equation. The results show that the maximum abrasive wear of the screw flights occurs on the opposite side of the scaffold. The abrasive wear of screw flights is greater when the scaffold is located directly above the middle of two adjacent screws than above a certain screw. The abrasive wear of equidistant screw flights is about twice the modified screw under the same scaffold condition. The findings of this study provide a theoretical basis for the optimization of the COREX shaft furnace.     

Unlubricated sliding of a titanium aluminide alloy against M2 tool steel

Abstract

This study is an extension of continuing research on the wear behaviour of gamma-TiAl base alloys, which has demonstrated how a surface reaction layer, made of native oxides, can dramatically improve the dry sliding wear resistance of the Ti-48Al-2Cr-2Nb-1B at.- alloy. The results presented provide a further insight on the wear behaviour of the coated alloy under different loading conditions. Moreover, specific attention has been paid to the study of the tribological coupling and of the wear mechanisms affecting an M2 steel counterface disc. The steel counterface is abrasively worn by the oxide asperities present on the alloy surface. Wear debris remains trapped between the sliding surfaces and gets oxidised. Therefore, wear debris may contribute to further accelerate the wear rate before leaving the system or being compacted on the wear tracks to form protective glazes. Once the main wear mechanism was clearly identified, some tests were conducted on alloy specimens which had their surface oxide mechanically smoothed. This operation proved to be very successful indeed. In fact as a result, not only did the gamma-TiAl alloy have a zero wear rate, but also a significant reduction of the abrasive contribution to the wear rate of the steel counterface was detected. Both these improvements were observed even at the highest load employed in the investigation 500 N.     

考虑研磨子——车轮和轮轨作用的城际动车组车轮磨耗预测

针对站间距短、研磨子频繁作用的城际铁路,建立了集车辆系统动力学、研磨子―车轮接触和车轮磨耗等模型于一体的动车组车轮磨耗预测模型,车轮磨耗采用Archard模型计算,实现了研磨子―车轮和轮轨接触对车轮磨耗贡献的定量预测。以中国南方某城际线路上运行的某型城际动车组为例,模拟了动车组车轮LM廓形在一个车轮镟修周期内的演化,通过对比跟踪测试结果,确定研磨子所致车轮磨耗的磨耗系数取1.45×10-4,并完成了模型验证。上述城际铁路的模拟结果显示,该模型的车轮磨耗预测误差仅为5.00%。以0.30 MPa工作气压下的高硬度研磨子为例,发现其最佳工作模式为“工作20 s—停止工作25 s”的间歇式工作模式。为动车组研磨子系统的优化设计提供有效模拟工具。     

基于切削振动相关性识别刀具磨损状态的模型与实验

本文提出基于切削振动相关性识别刀具磨损状态的研究思想,建立了车削中刀杆双向横振动系统及其单输入双输出系统的数学模型。理论和实验均表明,刀杆双向横振动之加速度响应在固有基频处的相干函数与刀具磨损状态之间有很好的规律性,它反映了两者之间的本质机理,并提供了识别刀具磨损状态的新途径。