法向载荷对不锈钢/浸金属碳载流摩擦磨损性能的影响

在自行设计的销-盘式摩擦磨损试验机上进行了不同法向载荷下不锈钢/浸金属碳载流摩擦磨损试验,分析了法向载荷对其摩擦磨损性能的影响,并用SEM观察了其磨损形貌。结果表明:摩擦因数随着法向载荷的增大而减小,160 N后基本趋向稳定;10 A电流时,浸金属碳销试样的磨损率很低,且增加趋势不明显,30～50 A电流时,磨损率显著提高,且浸金属碳销试样磨损率随着法向载荷的增大而减小,最后趋于平缓;此外,放电强度随着法向载荷的增大而减弱;在低法向载荷下,磨损类型以电弧烧蚀和氧化磨损为主,在高法向载荷下,磨损类型以磨粒磨损和粘着磨损为主,且都伴随有材料的转移。     

38CrSi自配副的摩擦磨损性能

采用自制的销盘式摩擦磨损试验机研究了38CrSi自配副干滑动时的摩擦因数、磨损率随滑动速度和载荷的变化规律;利用SEM观察了磨损面的微观形貌,分析了摩擦磨损机理。结果表明:其摩擦因数随着载荷和速度的增加而减小;磨损率随着载荷的增加而增大,随着速度的增加先增大后减小,和常用材料的磨损率随速度增加而增大的规律不同;磨损机理为磨粒磨损和粘着磨损。     

38CrSi自配副的摩擦磨损性能

采用自制的销盘式摩擦磨损试验机研究了38CrSi自配副干滑动时的摩擦因数、磨损率随滑动速度和载荷的变化规律;利用SEM观察了磨损面的微观形貌,分析了摩擦磨损机理。结果表明：其摩擦因数随着载荷和速度的增加而减小;磨损率随着载荷的增加而增大,随着速度的增加先增大后减小,和常用材料的磨损率随速度增加而增大的规律不同;磨损机理为磨粒磨损和粘着磨损。     

AS41镁合金在不同温度的摩擦学行为

研究了AS41镁合金在不同温度时的力学和摩擦学性能及摩擦学机理。研究结果表明:随着试验温度升高,AS41镁合金的抗拉强度和屈服强度降低、延伸率增大;当温度超过150℃时,抗拉强度和屈服强度显著下降。随着载荷增大,不同试验温度的摩擦因数均呈减小趋势,而磨损率则呈增大趋势;随着滑动速度增大,不同试验温度的摩擦因数变化不大,而磨损率则呈增大趋势。在不同载荷和滑动速度下,均呈现试验温度越高,摩擦因数越小,磨损率越大的现象;在试验温度较高时,导致磨损机制由轻微磨损向严重磨损转换的载荷减小。在载荷为50N时,不同温度AS41镁合金的磨损机理分别是:室温时主要为氧化磨损和磨粒磨损,150℃时为剥层磨损和黏着磨损,而200℃时主要为材料塑性变形引起的熔融磨损。     

载流条件下黄铜/Al_2O_3/Cu复合材料摩擦副的摩擦磨损性能

采用内氧化法制备了Al2O3/Cu复合材料,以该复合材料为销试样,黄铜(H62)为盘试样进行载流条件下的干滑动摩擦磨损试验,并对销试样摩擦表面进行微观形貌分析.结果表明:磨损率随着电流、速度和载荷的增大而增加,摩擦因数随着电流的增大而增加,随着速度和载荷的增大而减小;电流较小时摩擦表面具有磨粒磨损和粘着磨损的共同特征,电流较大时以粘着磨损为主;在试验条件下,Al2O3/Cu复合材料的抗摩擦磨损性能显著优越于紫铜.     

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.     

销盘磨损数值计算及结果分析

通过分析销-盘滑动摩擦副的受力情况,建立此二者间的磨损模型。在给定销径、载荷、转速、工作时间等条件下,计算出销和盘的各自的磨损率和磨损量以及组合磨损率和组合磨损量。计算结果表明:销、盘工作过程中,二者接触表面各点压力分布在整体上呈现出沿旋转半径增大的方向减小,然而在接近最大旋转半径处,压力略有上翘现象;销各点的磨损率也与旋转半径相关,随着半径增大,其磨损率由大逐渐减少,然后再逐渐增大,因此磨损后的表面形状是一个凸起的拱形;由于需要满足磨损协调条件,盘的各点的磨损率与销磨损相反的趋势,它磨损后的表面是一个环形凹槽,即沿盘的半径方向看,磨损后表面呈反向。     

PCrNiMo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PCrNiMo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；摩擦系数随着载荷的增加而减小，随着速度的变化规律是：先增大再减小。磨损机理主要为磨粒磨损和粘着磨损。     

载流条件下的1Cr18Ni9Ti/浸金属碳摩擦磨损性能研究

在销-盘摩擦磨损试验机上试验了载荷、速度、电流对1Cr18Ni9Ti/浸金属碳对磨时的摩擦因数、磨损量及磨损形貌的影响。试验结果表明,载荷对1Cr18Ni9Ti/浸金属碳摩擦副的摩擦因数和销试样的磨损率有显著影响:载荷越大,摩擦因数越大,磨损率越低;摩擦因数、磨损率与速度的关系受载荷的制约。当低载时,以电流影响为主。销试样的磨损表面出现了粘着磨损,氧化磨损和电弧烧蚀。     

磁场作用下45钢/45钢稳定摩擦的磨损机制

为研究不同强度磁场作用下45#钢自配副的磨损机制及磁场强度与磨损率的关系,在不同强度磁场作用下进行45钢自配副的销、盘干摩擦试验,分析销试样的磨损性能及其磨损面的形貌、化学成分。结果表明:随着磁场强度增加,销试样磨损率经历快速减小、缓慢减小和基本稳定3个连续变化阶段,使其由严重磨损转变为轻微磨损的临界磁场强度约为17. 4×10~3A/m;无磁场作用时,销试样磨损面存在犁沟,45钢/45钢的磨损类型为磨粒磨损;随着磁场强度的增加,销试样磨损面发生氧化并生成了Fe_2O_3,摩擦过程中氧化物剥落形成凹坑,45钢/45钢的磨损类型主要为氧化磨损;磁场增加使销试样磨损面更加光滑。可以得出:一定强度的磁场使45钢自配副摩擦过程由磨粒磨损转变为氧化磨损,而氧化磨损类型对应45钢自配副的轻微磨损。     

Effect of microstructure on the sliding wear performance of a Zn–Al–Ni alloy

Some observations pertaining to the sliding wear characteristics of a zinc–aluminium alloy containing nickel under varying material and test conditions have been reported in this investigation.

Dry sliding wear tests were conducted on as-cast and heat-treated zinc-based alloy pins using a pin-on-disc machine. A steel disc was employed as the counterface. Sliding speeds adopted were 0.42, 2.68 and 4.60 m/s while the traversal distance was fixed at 500 m. Wear tests were conducted at different pressures using separate pins in each case. Seizure pressure of the pins (prior to traversing the sliding distance of 500 m) was determined at each speed.

Wear rate and the extent of frictional heating increased with pressure and speed whereas seizure pressure practically followed a reverse trend. The wear rate versus pressure plot of the as-cast alloy pins assumed two slopes at the lowest speed wherein low slope (indicating the occurrence of mild wear situation) was noticed initially. This was followed by the attainment of a higher slope suggesting severe wear condition at increased pressures. At higher speeds, one slope only (identical to the higher slope at the minimum speed) was noted. Wear rate versus pressure plots of the heat-treated alloy pins followed a trend similar to the as-cast ones except that two slopes were noted up to the intermediate speed in the former case.

Heat treatment changed the as-cast dendritic structure of the zinc-based alloy into the one with an improved uniformity of the distribution of various microconstituents, the nickel containing phase remaining practically unaffected. Softening of the (as-cast) alloy was also observed as a result of the heat treatment. However, in spite of reduced hardness, the heat-treated alloy pins attained improved wear behaviour (i.e. reduced frictional heating and low wear rate) over the as-cast ones irrespective of the test conditions. This was attributed to a more uniform distribution of microconstituents and reduced cracking tendency of the alloy as a result of the heat treatment. The alloy pins also attained better seizure pressure in heat-treated condition comparing with the as-cast ones at all the speeds except the maximum for the same reasons. A reversal in the trend at the maximum speed was thought to be due to the over-softening of the already softened (heat-treated) alloy pins under the influence of large frictional heat generated at the (maximum) speed. Under the circumstances, the heat-treated alloy pins tended to adhere/fuse with the disc extensively while this tendency was relatively less for the as-cast ones in view of their higher hardness. Further, the extent of the negative influence of cracking tendency reduced allowing thermal stability to predominate the wear behaviour of the as-cast alloy pins in this case. The factor led to somewhat higher seizure pressure of the (as-cast) alloy pins at the maximum speed comparing with the heat-treated ones.

Low wear rates correlated with less damage to the worn surfaces and to the regions below the worn surfaces and finer debris formation. Seizure led to severe damage to the worn surfaces and to the regions below the worn surfaces while the debris formed was quite bulky and coarser.     

A method of calculating steady state wear rate of metals from profilometric traces

An asperity model is proposed in which it is assumed that a rider removes an amount of the asperity by shear across a plane inclined to the horizontal. Methods of calculating the true area of contact, the wear volume and the heights of the asperities are shown. Experiments were conducted in which brass pins were slid on steel flats using a reciprocating machine. It is shown that in the steady state the wear volume can be calculated from Talysurf traces.     

Debris control in dry wear testing

In a conventional wear test, debris accumulated from the repeated sliding of the wear pin over the same track dominates the nature of the interaction between the pin and the countersurface. Brush materials to remove the wear debris have been investigated so that more basic interactions between the pin and the countersurface can take place. The most successful brush was made from layers of Kimwipe (Kimberly-Clark of Canada Ltd.) laboratory tissue formed into a disc 8 cm in diameter and 2 cm thick. The Kimwipe disc was rotated under a load of 15 N at a frequency of 1 Hz across the wear track on the countersurface.The appearances and wear rates of steel 1040 and Admiralty brass pins worn in the presence and absence of debris were very different. Pins worn in the absence of debris readily assumed the characteristics of the pins worn in the presence of debris when debris was allowed to accumulate on the wear track. The mode of wear in debris-free conditions is not known at present, but this mode is worthy of further consideration. Worn surfaces are relatively flat and can appear metallic or covered with a light coat of oxide. Wear rates of oxide-coated pins can be either faster or considerably slower than those of uncoated pins. However, under all conditions debris-free wear involves considerably less subsurface metal flow than that involved when debris is present.     

表面强化销轴农用滚子链的磨损试验研究

对农机用滚子链条的主要磨损表面——销轴表面进行化学镀镍、镀硬铬、渗钒不同的表面强化处理,测量了三种销轴表面强化后及国外某公司同规格销轴的表面硬度及硬化层厚度.把三种销轴表面强化的链段与国外同节数的链段组装成一条链条,在LS910A封闭力流试验机上进行对比磨损试验.试验数据表明,在所提供的试验条件下,销轴表面镀硬铬链条具有更好的耐磨性能,优于国外的样品链条.     

Wear laws for polytetrafluoroethylene

Experiments were made to determine the effect of sliding speed, contact pressure and rubbing surface temperature on the wear of a polytetrafluoroethylene (PTFE) pin rubbed against a chromium-plated brass disk. An automatic temperature control type wear apparatus to control the rubbing surface temperature was constructed and used to minimize the influence of frictional heat. The linear wear rate is proportional to contact pressure to the nth power (n > 1). Wear curves of PTFE with a characteristic variation of the linear wear rate with sliding speed were obtained. Increase of contact pressure shifts the curves towards a higher wear rate. When the temperature was increased the curves were shifted towards a higher speed and higher wear rate. A master curve obtained by translation of each wear curve vertically or horizontally to fit the reference curve can be used to determine the wear rate.     

恒定动能作用下薄壁管的冲击微动磨损行为研究

在新型冲击微动磨损试验机上对四种常见材料的薄壁管(不锈钢、铜合金、纯钛和铝合金)进行了冲击磨损试验,考察了材料属性、冲击能量对薄壁管损伤行为的影响。对其冲击动力学行为、磨损行为进行了分析。研究结果表明,不同材料金属管的能量吸收率、冲击接触力和冲击管变形有显著差异;同一种材料,随着初始冲击动能的增大,冲击过程中接触力、冲击管变形和冲击吸收能也在增大。通过分析磨痕微观形貌和磨痕轮廓,发现薄壁管的冲击磨损抵抗性能与材料属性密切相关;随着初始冲击动能的增加,材料损伤加剧,其损伤机制为疲劳磨损。     

新型Hy-Vo齿形链磨损特性的研究

通过分析计算以及300h的台架磨损试验,研究了新型Hy-Vo齿形链的耐磨特性,结果表明,由于新型Hy-Vo齿形链的一对对滚异型销轴以滚动摩擦为主交替承载磨损,其承载表面比压值较普通滚子链以及圆销式齿形链低,新型Hy-Vo齿形链具有较高的耐磨性。对新型Hy-Vo齿形链的异型销轴、内-外复合啮合链板以及外啮合链板的磨损表面作了SEM形貌分析。销轴的磨损机制为疲劳磨损,工作链板的磨损机制为磨粒磨损和疲劳磨损。     

汽车发动机正时套筒链道路试验及磨损特性研究

通过道路试验研究,分析了汽车正时套筒链的磨损机制及销轴和套筒的磨损表面形貌。结果表明:在压力喷油润滑条件下汽车正时套筒链的磨损机制是以疲劳磨损为主,并伴有磨粒磨损;摩擦热导致位错密度下降是销轴和套筒摩擦表面循环软化的主要原因;随着道路试验里程的增加,由于微动磨损的不断加剧,其销轴与外链板孔、套筒与内链板孔的联结牢固度在逐渐降低。     

黄铜全流量在线磨粒静电监测实验研究

为深入了解静电监测方法对黄铜的监测能力,采用自制的全流量在线磨粒静电传感器开展黄铜的静电监测方法研究。研究了润滑条件下轴承钢-黄铜滑动摩擦荷电磨粒的产生机理并设计了磨粒静电监测系统,开展了三种尺寸的轴承钢球和黄铜球的单颗粒注入实验、双颗粒注入实验以及相同载荷、不同滑动速度的轴承钢-黄铜滑动摩擦磨损实验,对摩擦因数、静电感应信号、静电信号均方根值进行相关性分析。研究结果表明:全流量在线磨粒静电传感器具有较好的检测一致性;静电监测方法对黄铜的监测能力强于对轴承钢的监测能力;摩擦因数与静电监测信号具有相关性,在磨损阶段,静电感应信号出现脉冲尖峰与持续上升。     

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。