MgO/SiO2复合纳米添加剂的自修复性能试验研究

以纳米MgO/SiO2作为添加剂,在HQ-1摩擦磨损实验机上进行自修复实验。试验考察载荷、转速、修复时间对纳米MgO/SiO2复合添加剂自修复性能的影响。实验结果表明,纳米MgO/SiO2在适宜的条件下对钢-钢摩擦副磨损金属表面有修复效果,其修复性能受载荷、转速及修复时间等条件影响;纳米MgO/SiO2添加剂对磨痕具有一定的填平作用,在一定程度上能够改善磨痕的粗糙度。     

纳米TiO2的磨损自修复特性

为研究纳米TiO2的磨损自修复作用及摩擦条件对修复的影响,将纳米TiO2作为添加剂加入350 SN基础油中,采用HQ-1环决摩擦磨损试验机考察了纳米TiO2对磨损表面的修复作用,在不同载荷、转速、修复时间条件下进行了磨损试验,以质量变化及粗糙度变化来评价添加剂的修复效果.结果表明:纳米TiO2添加剂对磨损表面具有良好的修复作用,修复后表面粗糙度降低了10.26%;其自修复性能受载荷、速度、摩擦时间的影响.     

纳米锌粉的摩擦自修复研究

将纳米Zn作为添加剂加入350SN基础油中,在WMW-1P立式多功能试验机上考察纳米Zn对磨损表面的修复作用,并探讨了摩擦条件下对修复效果的影响.结果表明,纳米zn添加剂对磨损表面具有良好的修复作用,其修复性能受摩擦条件的影响.在适当的摩擦条件下,试环有明显的增重,修复后磨痕表面粗糙度降低了13.5%,扫描电子显微镜及能谱分析表明磨痕表面覆有一定厚度的金属zn层,其质量分数为97.68%.     

ZnO纳米微粒作为润滑油添加剂的摩擦学作用机理

通过实验研究了 Zn O纳米微粒作为润滑油添加剂的摩擦学特性 ,提出了作用机理模型。在润滑油中同时加入 Zn O纳米微粒和分散剂可显著改善润滑油的耐磨减摩性能。其作用机理是 ,分散剂吸附在 Zn O纳米微粒团簇表面 ,然后共同吸附在摩擦副表面 ,在剪切力的作用下 ,Zn O纳米微粒团簇分割成更小的单元 ,当载荷继续增大时 ,Zn O纳米微粒处于熔化或半熔化状态 ,从而起到降低磨损 ,减小摩擦的作用     

纳米TiN润滑油添加剂的摩擦学性能研究

使用四球摩擦试验机研究纳米TiN作为润滑油添加剂的摩擦学性能, 并利用磨斑测量系统、激光共聚焦显微镜OLS1100和EDS测试分析其磨损特性和自修复性能。实验结果表明：纳米TiN作为润滑油添加剂具有良好的抗磨减摩和自修复性能;在润滑油中加入质量分数为05%的纳米TiN添加剂和10%的PEG 200分散剂,可达到最佳的抗磨减摩效果。在高载荷下,纳米TiN润滑油的自修复比表面抛光的效果更好。     

不同工况对金属磨损自修复层形成的影响

为了研究不同的工况对金属磨损自修复层的形成所产生的影响,以羟基硅酸镁为自修复剂,通过改变转速、载荷、磨损时间和磨损介质等试验工况,利用销盘磨损试验机模拟了缸套-活塞环的磨损状态.结果表明,在摩擦条件适当时,试样盘表面会形成一层平整光滑的保护层,但表面仍然存在细微的裂纹和一些微小的坑洞,修复层不会随磨损时间的增加而脱落或造成磨损加剧,另外金属磨损自修复剂在水介质中难以形成保护层.     

含超细SiO_2/MoS_2粉锂基润滑脂摩擦学性能研究

采用四球摩擦磨损试验机研究了纳米SiO_2及超细MoS_2的粒径、添加量和载荷对2~#锂基脂摩擦学性能的影响,并研究了2种超细粉复配比例和载荷对2~#锂基脂摩擦学性能的影响。结果表明:单一纳米SiO_2和超细MoS_2的加入均能明显减小润滑脂的摩擦因数和钢球磨斑直径,纳米SiO_2和超细MoS_2的复配有助于进一步改善含超细粉锂基脂的摩擦学性能。当纳米SiO_2与MoS_2质量比为2∶8,总加入质量分数为2.0%时,润滑脂的摩擦因数和钢球磨斑直径较基础脂分别减小了77.1%和46.42%。利用SEM和EDS分析磨斑表面形貌及元素组成,初步探讨了含超细复合粉润滑脂的抗磨减摩机理。SEM和EDS分析表明:纳米SiO_2在摩擦过程中主要作用是填补磨痕沟壑,而超细MoS_2除填补沟壑外还对摩擦副表面有抛光研磨和形成减摩膜的作用,2种超细粉的协同使润滑脂具有自修复和抗磨、减摩作用。     

复合纳米粒子作为润滑油添加剂的摩擦学性能

研究了复合纳米粒子作为添加剂对润滑油摩擦学性能的影响.将改性纳米CaCO3和纳米Zn按一定质量分数进行复配后,加入到液体石蜡中,采用摩擦磨损试验机考察了其摩擦学性能;并采用正交试验方法分析了2种纳米粒子的最佳配比和最佳添加量.结果表明,复合纳米粒子综合了CaCO3和Zn 2种纳米粒子的性能,作为润滑油添加剂,比单一的纳米CaCO3和纳米Zn添加剂有更好的抗磨减摩性能;在本文试验条件下,纳米CaCO3和纳米Zn的质量比为1∶1,总质量分数为0.6%时,配制的润滑油具有更好的抗磨减摩性能.     

含纳米镍粉齿轮油摩擦学性能研究

为提高传统齿轮油的摩擦学性能,选择高速剪切和纳米镍粉表面修饰相结合的分散方式制备含纳米镍粉的齿轮油,采用四球试验机研究高速剪切转速和时间、KH560分散剂及纳米镍粉加入量对齿轮油摩擦学性能的影响,并采用SEM和EDS等对磨斑形貌和成分进行分析表征,初步探讨其抗磨减摩机制。结果表明:高速剪切转速为3 000r/min,剪切时间为30 min,分散剂KH560质量分数为6%时,纳米镍粉在齿轮油可的分散效果最好;纳米镍粉质量分数为0.5%时,齿轮油综合摩擦学性能较好,摩擦因数和磨斑直径较未添加镍粉的齿轮油分别下降25.5%和22.6%;含纳米镍粉齿轮油在不同载荷下均具有较好的减摩性能,但只在较低压力下具有较好的抗磨性能。磨痕形貌及能谱分析结果表明:在摩擦过程中含纳米镍粉齿轮油中的纳米镍粉能起到填平犁沟、修复磨痕表面的作用。     

不同纳米添加剂下GCr15/45钢自修复性能研究

利用高精度液压式往复试验机研究了纳米羟基磷酸钙、纳米二氧化钛、纳米氮化钛3种纳米添加剂润滑条件下GCr15/45钢对摩时的摩擦磨损性能,通过扫描电子显微镜和EDX能谱对磨斑进行了微观分析。结果表明:纳米润滑添加剂可以降低摩擦副摩擦因数和材料磨损量,表现出优良的抗磨损性能;3种纳米添加剂具有不同的自修复机制,其中纳米羟基磷酸钙和纳米二氧化钛的修复机制主要为铺展成膜自修复,而纳米氮化钛为铺展成膜自修复和原位摩擦化学自修复并存;纳米氮化钛的自修复效果最佳,纳米二氧化钛的自修复性能最差。     

金属纳米复合粉体改善润滑油的摩擦磨损性能研究

研究了金属纳米铜镍复合粉体的添加量对润滑油极压、抗磨性能的影响，考察了载荷变化对添加铜镍复合粉体润滑油减摩性能以及长效减摩性能的影响。结果表明，铜镍复合粉体的添加对提高润滑油的极压性和抗磨性能有显著作用，铜镍复合粉体的质量分数为0．05％时可使PB值提高52．6％，质量分数为0．3％时，油样的PB值达到最大696N，提高了77．6％。当铜镍复合粉体的质量分数达到0．1％时，磨斑直径降低幅度最大，达35．6％，并具有很好的长效减摩性能。研究还发现金属纳米铜镍复合粉体在高载荷下具有很好的减摩性能。     

基于UHMWPE/纳米ZnO复合材料的滑动摩擦磨损机制

用热压成型法制备了超高分子量聚乙烯(UHMWPE)纳/米ZnO复合材料,采用销盘式摩擦磨损试验机考察了载荷和相对滑动线速度对复合材料摩擦学性能的影响;采用扫描电子显微镜观察了复合材料磨损表面形貌。结果表明:在低载荷试验条件下磨损机制为粘着磨损,在高载荷试验条件下磨损机制为粘着磨损和疲劳磨损。而在一定载荷试验条件下,无论相对滑动线速度高或低,复合材料的磨损机制主要表现为粘着磨损,只是在高速情况下粘着磨损程度加大,局部还出现了表面撕裂的痕迹。     

摩擦磨损自修复原理及纳米自修复添加剂研究进展

摩擦磨损导致能源浪费和零部件失效,纳米自修复添加剂能够降低摩擦磨损,延长机械的使用寿命,还可在不拆卸的情况下对机械零件表面进行在线修复,实现终身免大修,给传统的维修带来了全新的理念。探讨了摩擦磨损自修复的原理,指出摩擦磨损自修复的原理主要有摩擦自修复、原位摩擦自修复和摩擦自适应修复等。概述了几种纳米自修复添加剂的研究应用现状,包括纳米金属粉末、纳米金属氧化物、纳米硫化物、纳米硼系和稀土类化合物及其它新型纳米材料。     

碳纤维改性热塑性聚酰亚胺材料摩擦磨损性能

通过正交实验设计和方差分析，系统考察了工况（温度、速度及载荷）对碳纤维改性热塑性聚酰亚胺（TPI）摩擦磨损行为的影响。用电子显微镜（SEM）观察其磨损面形貌分析材料磨损机制。研究表明：随着温度升高，分子链相对滑移增强，体现出良好的自润滑特性，材料的摩擦因数和磨损率均有所下降；排除摩擦热的干扰，方差分析表明载荷、速度及其交互作用对材料摩擦磨损行为影响不显著。根据粘着摩擦理论，载荷的改变对材料抗剪切强度无明显作用，表现为材料摩擦磨损性能稳定。随速度的增加，材料抗剪切强度呈现下降趋势，同时考虑到受力中的塑形硬化现象，摩擦因数出现先增后减的变化。     

A study of the anti-wear and friction-reducing properties of the lubricant additive, nanometer zinc borate

Nanometer crystal zinc borate with a particle size of 20–50 nm was prepared using the ethanol supercritical fluid drying technique. Tribology properties of 500 SN oil containing nanometer zinc borate particles thus prepared were measured. Results indicated that compared with the base oil the wear resistance and load-carrying capacity of the oil were improved and the friction coefficient was decreased. There was an optimal content of zinc borate, and the corresponding oil gave the highest maximum nonseized load. Diboron trioxide was formed and tribochemical boronization took place in friction. Nanometer zinc borate took effect by deposition of diboron trioxide on the rubbing surface and tribochemical boronization.     

Experimental Study on the Effect of Microstructure on Dry Sliding Wear Behavior of Titanium Alloy Using Taguchi Experimental Design

The present article depicts the influence of independent control factors such as microstructural variation, normal load, sliding velocity, and test duration on the dry sliding wear behavior of titanium alloy at room temperature using a statistical approach. Different heat treatments were carried out in a controlled manner to produce various microstructural features (i.e., lamellar, bimodal, and equiaxed) in this alloy. A lamellar microstructure is found to be harder than bimodal microstructure followed by an equiaxed microstructure in this alloy. Dry sliding wear tests were carried out using a multiple tribotester following a well-planned experimental schedule based on Taguchi's orthogonal arrays. The dry sliding wear behavior of this alloy consisting of various microstructural features is related to their hardness values. The results indicated that a lamellar microstructure has the lowest sliding wear resistance followed by bimodal and equiaxed microstructures. Using signal-to-noise ratios and analysis of variance (ANOVA), an optimal combination of control factors that minimize the dry sliding wear in this alloy were determined. Among all four control factors, normal load is the most significant control factor influencing the dry sliding wear behavior of the investigated titanium alloy, followed by microstructural variation, sliding velocity, and test duration. Normal load has a greater static influence of 39.53%, microstructural variation has an influence of 31.55%, sliding velocity has an influence of 21.6%, and test duration has an influence of 5.7% on the dry sliding wear of this alloy. Two wear mechanisms were identified: oxidative wear occurs at the lowest sliding velocity and delamination wear occurs at the highest sliding velocity. Optical microscopy, scanning electron microscopy, and Rockwell hardness measurements were used to characterize the microstructures in order to correlate the results obtained.     

The Study of Arc Rate,Friction, and Wear Performance of C/C Composites in Pantograph–Catenary System

A series of tests on arc rate, friction coefficient, and wear rate of electrical current collectors sliding against overhead contact wires under different conditions was carried out on a high-speed friction and wear testing machine with a pin-on-disc configuration. The worn surface morphology and composition were examined using a scanning electron microscope and energy dispersion spectrum analyzer, respectively. The effects of current, velocity, and load on the arc rate, friction coefficient, and wear rate of C/C composites/QCr0.5 couples were investigated, and the influence mechanism of test parameters on C/C composites was explained. It is concluded that the wear rate increases with an increase in current and velocity and has a decreasing trend with the increase in load. The friction coefficient increases with an increase in velocity and load. The arc rate of C/C composites/QCr0.5 couples increases with an increase in current and velocity. Under the condition of the same current and velocity, when the load is 70 N, the arc rate is the lowest.     

Effect of Spot Continual Induction Hardening on the Tribological Performance of Grey Cast Iron with Curved Surface

In order to investigate the effect of a spot continual induction hardening (SCIH) process on the tribological performance of grey cast iron with a curved surface, dry sliding wear tests were performed under different loads. The curved surface structure of the workpiece and feed velocity of the inductor were considered important influence factors. X-ray diffractometry (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) were used to investigate the phases, compositions, and morphologies of grey cast iron after the SCIH process and tribological tests. The results showed that the wear mechanism of grey cast iron was always adhesive and abrasive wear at different loads when the workpiece was not strengthened. In the case of partial strengthening, the wear mechanism changed from adhesive and abrasive wear to fatigue–exfoliative wear with increasing load. Oxidative wear always appeared as the dominant wear mechanism when the workpiece was completely strengthened. The wear resistance of the concave surface was always larger than that of the convex surface under the same feed velocity of the inductor. Relatively low feed velocity of the inductor in the SCIH process can optimize the wear resistance of grey cast iron with a curved surface.     

Tribological behaviour of carbon–carbon composite

Abstract

In the present study, the wear behaviour of cross ply (0/90°) C–C composite with 60 vol.-% fibres has been studied with sliding distance, applied load and sliding velocities. The measurement of specimen temperature has been carried out to study the effect of frictional heating. Furthermore, wear debris and wear track observations are correlated to understand the wear mechanism. The bulk wear increases linearly with distance after an initial running-in period. The temperature studies reveal that frictional heating is more with increase in load or sliding velocity under dry conditions, however, presence of lubrication reduces frictional heating, because exposure of surface for direct contact is reduced, and hence wear rate in all studies with lubrication is less than that under dry condition. The wear track studies show graphite powder, peeling of fibres and dislodging of the surface. At low loads, smearing of graphite powder keeps the wear rate low, but as the load increases; dislodging, delamination of surface and breaking of fibres dominate, and wear rate sharply increases, however, sliding velocity initially enhances the graphite formation reducing the wear, but as the velocity reached an optimum value, there is extensive breakage of fibres, dislodging and delamination of surface, and the wear rate increases sharply.