粘结固体润滑涂层在油润滑条件下的摩擦学性能

为了探讨粘结MoS2基固体润滑涂层在油润滑条件下的抗磨减摩性能,采用MHK-500型摩擦磨损试验机对粘结MoS2基固体润滑涂层在4种常用油(液体石蜡、RP-3煤油、4050滑油和CD-40柴油)润滑下的摩擦磨损性能进行了研究,考察了速度和载荷对润滑涂层在4种不同的常用油润滑下的摩擦磨损性能。结果表明,在低载荷(320N)试验条件下,4种常用油润滑下涂层的耐磨性比干摩擦下得到显著的提高,摩擦因数从0.12降低到0.08左右;但在高载荷(1100N)下,油润滑对涂层的摩擦磨损性能没有明显的改善。只有在合适的载荷下,固/油复合润滑技术可明显改善摩擦副的润滑性能。     

水润滑橡胶/镀镍钢配副摩擦磨损机理研究

对水润滑轴承专用橡胶／镀镍钢配副分别在干摩擦、边界润滑条件下用数显式高速环块摩擦磨损试验机进行了摩擦磨损试验，并借助SEM分析了其摩擦磨损机理。结果表明：千摩擦条件下主要为粘着磨损，边界润滑条件下主要为磨粒磨损。     

Ag膜在干摩擦、油和脂润滑下的摩擦学性能研究

精密运转部件表面沉积一层软金属银和银基固体薄膜可以有效地降低摩擦、减小磨损。通过钢球/镀Ag膜摩擦盘在干摩擦、4122油和L252脂润滑条件下的球-盘摩擦学试验,研究Ag膜在油和脂复合润滑下的摩擦学性能,分析润滑条件、载荷、速度对Ag膜摩擦因数的影响。试验结果表明:在4 N法向载荷和油、脂润滑下,与干摩擦相比,镀Ag膜摩擦副的最大静摩擦因数分别减小了10.7%和6.1%;在0～2 000 r/min转速范围内,Ag膜摩擦因数随转速增加而减小,与干摩擦相比,油润滑下Ag膜摩擦因数减小9%～48%,脂润滑下Ag膜摩擦因数减小17%～52%。Ag膜在干摩擦、4122润滑油和L252润滑脂复合润滑下,摩擦因数均随载荷增加而降低;Ag膜摩擦副/钢球在油、脂复合润滑下启动摩擦力矩小,摩擦副在宽转速范围内摩擦因数变化小,运转平稳。     

不同润状态下炭纤维对锡青铜摩擦磨损性能的影响

短碳纤维增强锡青铜（碳／锡青铜）复合材料分别在干摩擦和有油滑状态下与钢进行了滑动对磨试验，研究了试验条件及碳纤维含量等因素对复合材料摩擦磨损性能的影响。试验结果表明，碳纤维对锡青铜摩擦磨损性能的影响行为与润滑状态有关，干摩擦时碳纤维的加入可以明显提高锡青铜的摩擦磨损性能，而有油润滑时碳纤维对锡青铜的摩擦磨损性能不仅没有改善，还会带来损害。     

不同润滑状态下炭纤维对锡青铜摩擦磨损性能的影响

短碳纤维增强锡青铜(碳/锡青铜)复合材料分别在干摩擦和有油滑状态下与钢进行了滑动对磨试验,研究了试验条件及碳纤维含量等因素对复合材料摩擦磨损性能的影响。试验结果表明,碳纤维对锡青铜摩擦磨损性能的影响行为与润滑状态有关,干摩擦时碳纤维的加入可以明显提高锡青铜的摩擦磨损性能,而有油润滑时碳纤维对锡青铜的摩擦磨损性能不仅没有改善,还会带来损害。     

钢-钢摩擦副在不同润滑和接触形式下的高温减摩性能的研究

用多功能SRV试验机评价了在干摩擦和油润滑条件下,试验参数对钢-钢摩擦副在点接触和线接触形式下的高温减摩性能的影响。结果表明,在试验范围内,随着试验负荷的增大,钢-钢摩擦副在干摩擦条件下线接触摩擦因数和点接触摩擦因数呈逐渐下降的趋势,这种下降趋势在线接触时尤为明显;但在油润滑条件下,试验负荷的增大对钢-钢摩擦副之间的线接触和点接触摩擦因数的影响不显著。在干摩擦条件下,不论是在点接触还是线接触形式下,试验速度对钢-钢摩擦副之间的高温点接触和线接触摩擦因数的影响并不显著;但在油润滑条件下,试验速度对钢-钢摩擦副的高温线接触和点接触摩擦因数的影响都比较显著,特别是在较高的试验速度时影响更为明显。     

干摩擦和水润滑条件下单晶硅的摩擦磨损性能研究

在UMT-2微摩擦试验机上,对单晶硅片进行了干摩擦和水润滑两种状态下的摩擦磨损试验,分析讨论了载荷和滑动速度对单晶硅片的摩擦因数和磨损率的影响规律;运用扫描电子显微镜,观察和分析了其磨损表面形貌。结果表明:干摩擦条件下的磨损机理主要表现为黏着磨损,水润滑条件下的磨损机理主要表现为机械控制化学作用下的原子/分子去除过程;水润滑条件下的摩擦因数和磨损量均较小,最小磨损率仅为10μm3/s;在水润滑条件下,载荷和滑动速度达到一定值时,硅片表面将发生摩擦化学反应,生成具有润滑作用的Si(OH)4膜,即机械作用在一定条件下对化学反应具有促进作用。     

铁基材料表面粘结润滑涂层摩擦学性能研究

为改善铁基粉末冶金材料的摩擦磨损性能,在其表面制备了复合粘结润滑涂层,分别在干摩擦和油润滑条件下进行摩擦磨损试验与分析,结果表明:石墨、二硫化钼两者有协同作用,复合粘结润滑涂层具有良好的润滑减摩性能,油润滑条件下,涂层以石墨含量较多者为佳,干摩擦条件下,涂层以MoS2含量较多者为佳,采用硅烷偶联剂处理后,进一步提高了复合涂层的减摩耐磨性能和承载能力.     

青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能

在MM-200摩擦磨损试验机上研究了青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能,采用扫描电镜(SEM)对磨损表面形貌进行了观测和采用X射线能谱分析(XPS)分析了涂层成分。结果表明,在水润滑条件下涂层摩擦因数和磨损率均低于干摩擦条件下;在水润滑条件下磨损机制为轻微磨粒磨损和犁削磨损,在干摩擦下主要是较为严重的粘着磨损和犁削。这是由于水润滑降低了摩擦副界面温度,提高了石墨润滑膜的韧性,改善了润滑效果,从而阻止了粘着磨损的发生,水还促进了钢偶件表面致密氧化膜的形成,从而减轻磨损。因此水润滑对涂层磨损性能有较大影响。     

镀银膜轴承在油和脂润滑下的摩擦性能

试验研究镀银膜轴承在干摩擦、润滑油和润滑脂复合润滑下的摩擦性能。试验结果显示:在中低转速下,镀银膜轴承在银膜和液体润滑剂(油和脂)复合润滑下的摩擦因数仅相当于银膜干摩擦下摩擦因数的10%左右,且变化平稳;在高转速下,试验轴承在银膜和液体润滑剂复合润滑下的摩擦因数随转速增加而增加,且银膜与润滑脂复合润滑条件下的摩擦因数随转速增加得更快,但仍小于银膜干摩擦下的摩擦因数;镀银膜轴承在银膜和液体润滑剂(油和脂)的复合润滑下的磨损小于银膜干摩擦时的磨损;中低转速下,镀银膜轴承在液体润滑剂(油和脂)复合润滑下的摩擦磨损性能远优于银膜干摩擦时的摩擦磨损性能。     

Tribological behaviour of thermally sprayed silicon carbide coatings

SiC coatings have been successfully deposited using thermal spray detonation technique with a newly patented feedstock. Their tribological performance was compared to bulk SiC for dry and lubricated conditions (polyalphaolefin and 3.5 wt% NaCl solution). The lowest coefficient of friction (CoF=0.10) and wear-rate were detected with polyalphaolefin lubricant regardless of the test pair due to mixed fluid-film lubrication. Contradicting results were recorded under other test conditions. The coatings show low CoF of 0.20 in comparison to four times higher CoF of bulk SiC under dry sliding. Oppositely, SiC coatings in NaCl solution record five times higher CoF compared to bulk SiC CoF of 0.20. Such behaviour is associated with tribochemical reaction and tribo-corrosion mechanisms occurring in dry and NaCl sliding, respectively.     

一种新型摩擦材料在水润滑下的摩擦学性能研究

采用环块式摩擦磨损实验研究了一种新型摩擦材料在水润滑状态下不同载荷与转速对试样摩擦学性能的影响,并对比干摩擦条件下的摩擦学性能变化,借助磨损表面形貌观察分析其磨损机理。实验结果表明:水润滑条件下,摩擦系数随着载荷的增大而减小,随着转速的提高先增加后减小;磨损率随着载荷与转速的提高都减小。相同载荷与转速下,干摩擦时磨损机理以磨粒磨损和黏着磨损为主,而水润滑条件下水形成边界润滑,磨损机理以磨粒磨损和轻微的黏着磨损为主;水润滑条件下摩擦系数和磨损率均低于干摩擦,主要是由于水起到了润滑和冷却的作用,阻止了转移膜的形成,并在材料表面形成水膜起到了边界润滑的作用。     

甘油润滑下CrCN涂层的超低摩擦特性

为开发与CrCN涂层具有良好配伍润滑性能的绿色润滑剂,使用磁控溅射技术在304不锈钢表面沉积CrCN涂层,利用场发射扫描电子显微镜、原子力显微镜、纳米压痕仪、维氏硬度计、X射线衍射仪、X射线光电子能谱仪分别对其表面形貌、涂层厚度、力学性能、物相组成以及元素化学价态进行分析,并借助多功能摩擦磨损试验机评价在甘油润滑下CrCN涂层的摩擦学性能,并与PAO6润滑下结果进行比较。利用磁控溅射技术在不锈钢表面构筑的CrCN涂层表面光滑致密,粗糙度仅为1.01 nm,硬度可达14.39 GPa。对比钢-钢和钢-CrCN体系的摩擦学性能发现,钢-CrCN体系在甘油润滑下展现出优异的润滑性能;当负载为0.5 N时,钢-CrCN体系在甘油润滑下的摩擦因数可低至0.01,大大低于PAO6润滑下的摩擦因数。对磨痕的XPS分析表明,在摩擦过程中,甘油发生摩擦化学反应,在CrCN涂层的接触表面生成一层FeOOH层,甘油分子及其降解产物可能进一步吸附在FeOOH层,形成流体润滑层,有效降低了摩擦和磨损。     

Friction and Wear Properties of Micro Textured DLC Coated Surfaces in Boundary Lubricated Sliding

In the present study, the friction and wear properties of boundary lubricated textured surfaces were investigated. The capability to feed lubricant into the interface of a sliding contact and to isolate wear particles was related to the shape, size and orientation of the texture patterns. Well-defined surface textures of square depressions or parallel grooves of different widths and distributions were produced by lithography and anisotropic etching of silicon wafers. Subsequently the wafers were PVD coated with thin, wear resistant DLC coatings, retaining the substrate texture. The surfaces were evaluated in reciprocating sliding against a ball-bearing-steel ball under starved or amply lubricated boundary lubrication conditions.     

Porosity Effect of Sintered Steel on the Frictional Performance of Conformal and Nonconformal Lubricated Contacts

Abstract

The effect of surface topography on lubricated systems plays a crucial role in terms of friction performance, because surface micro-irregularities can improve the load-carrying capacity of mechanical parts in lubricated conformal and nonconformal contacts. Sintered materials, which can be applied to manufacturing several mechanical components such as gears, axial thrust bearings, and disc brake pads, are interesting candidates, because they present pores that could be somewhat compared to microcavities produced by surface texturing techniques. This work aims at studying the influence of surface pores originated from the sintering process on the frictional performance of lubricated contacts under different lubrication regimes and slide-to-roll ratios (SRR). The research contributes to understanding how random micro-irregularities could change lubrication conditions and promote effects similar to those of more expensive and precise surface features produced by texturing techniques. The experimental results showed that a decrease in porosity led to a reduction in the coefficient of friction. Furthermore, less porous samples promoted friction reduction compared to nonporous materials due to the probable additional load support caused by small-scale surface pores. Therefore, in addition to the traditional appeal of the use of sintered materials to reduce production costs, the present contribution reveals that this type of material could also be used to reduce friction in contacting mechanical components operating under certain tribological conditions.     

石墨干膜润滑剂在碳钢表面摩擦磨损性能试验研究*

传统油或脂润滑剂在极端工况环境下无法满足碳钢类零件的减摩要求,采用干膜润滑剂是提高极端工况环境下碳钢表面摩擦磨损性能的可行性方法。采用超声波分散方法制备以石墨粉末为基体的干膜润滑剂,使用压力喷涂技术使其沉积在碳钢试件表面,在端面摩擦试验仪中开展干摩擦和石墨干膜润滑剂润滑下摩擦磨损性能对比性试验研究。试验结果表明：石墨干膜润滑剂在碳钢表面的沉积效果较好,沉积的石墨干膜润滑剂具有较好的润滑性能,可以有效地保护碳钢表面不被过度磨损;喷涂石墨干膜润滑剂的碳钢试件的工作寿命随着压力载荷和主轴转速的增大而缩短,负载和滑动速度的联合作用会加速涂层向稳定方向的过渡;磨损过程中形成的微观润滑剂颗粒会形成颗粒流润滑,适当添加石墨颗粒粉末可能会延长润滑剂正常发挥减摩作用的时间。制备的石墨干膜润滑剂为碳钢在极端工况环境下的减摩提供了支持。     

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。     

Experimental and numerical study of friction in an elastomeric seal for pneumatic cylinders

The behaviour of an elastomeric seal for a pneumatic cylinder piston is analysed in this work. The aim of the paper is to validate experimentally a numerical approach to evaluate seal performance, in actual working conditions.The friction force between seal and the cylinder bore is evaluated through experimental tests and numerical simulations, using a finite element model. Working conditions are simulated for different piston rod velocity and cylinder supply pressure, both in dry conditions, boundary and fluid lubrication conditions. Simulation is obtained by an iterative process that uses the friction coefficient, experimentally measured, as a function of speed and lubrication conditions. Results obtained from experimental tests and numerical simulation are compared to determine the friction force between seal and cylinder bore.     

Basics of mixed lubrication

This paper reviews recent research in mixed lubrication, focusing on the current understanding of lubricant entrainment, and thus film thickness, and of friction in thin‐film, rough‐surface lubricated contacts. By combining research using optical interferometry on the experimental side and numerical modelling on the theoretical side, we now have a reasonable understanding of micro‐elastohydrodynamic lubrication, although design rules are still lacking. The regime of true mixed lubrication, where there are both elastohydrodynamic and boundary lubricated regions within a single contact, remains quite poorly understood. New experimental techniques as well as new information about very thin‐film rheology under high‐strain and high‐pressure conditions are probably needed before much further progress can be made in this area.