电化学反应过程中黄铜表面的原位显微拉曼光谱分析

利用显微共焦拉曼光谱仪在线分析了在以十二烷基硫酸钠水溶液为电解液、石墨为辅助电极时电化学反应过程中黄铜表面化学成分的变化，进而分析了外加电压引起摩擦因数变化的机理。结果表明：外加电压对摩擦因数的控制主要通过对表面有机离子吸附膜的影响来实现；黄铜表面存在有机离子吸附或反应而形成的边界润滑膜时摩擦因数较低；黄铜表面不存在有机离子润滑膜而存在较多的氢氧根离子时摩擦因数较高；溶液的搅拌对电控摩擦的恢复有较重要的作用。     

材料摩擦因数的可控性研究

在边界润滑状态下采用轴承钢、黄铜等不同摩擦副材料，对一些通用和特殊润滑材料在外加电场作用下摩擦因数的变化进行试验研究，探讨了它们的摩擦控制性能。结果表明：尽管外加电场都能改变这些润滑剂的摩擦因数，但只有BH－1型铁磁流体具有比较理想的摩擦控制性能，说明摩擦可控性并不是润滑材料普遍具有的性质。     

双电层电粘度对薄膜润滑影响的试验研究与数值分析

由于固液界面处存在双电层,理论和试验研究都表明该效应对薄膜润滑有较为明显的影响。首先,利用自行设计的外加电场重构双电层装置进行了组合滑块水润滑试验,结果分析表明:双电层所引起的电粘度效应对流体润滑中摩擦因数有明显影响,另外当摩擦副的材料不同时,摩擦因数的变化规律不同。然后,又对KCl(氯化钾)溶液进行了组合滑块试验,进一步研究了离子浓度对电粘度效应的影响,在不同速度和溶液浓度的工况下,对摩擦因数进行了测量。结果表明:低浓度溶液使摩擦因数明显增加,浓度高时摩擦因数减小;随着速度的增加,双电层效应对摩擦因数的影响减小。最后,对试验工况进行了数值分析。     

外加电场作用下双电层电粘度对水润滑特性的影响

根据双电层理论,建立了外电场作用下流体润滑中的双电层引起的电粘度效应的数学模型,并通过组合滑块水润滑试验考察了双电层的电粘度效应对流体润滑性能的影响。结果表明,外加电场作用下,双电层电粘度效应对摩擦因数具有明显影响;当速度较低时,随着外加电压的增加,摩擦因数明显增大;随着速度的增加,摩擦因数增大幅度减小;试验结果同所建立的数学模型相符。     

面接触下水合羟乙基纤维素的润滑特性研究

以羟乙基纤维素(HEC)作为水基润滑添加剂,研究面接触条件下HEC润滑液的润滑特性。采用红外光谱仪分析HEC化学组成,结合分子动力学模拟分析HEC与水分子的相互作用,采用白光干涉三维表面形貌仪测量试样的表面形貌,借助微摩擦磨损试验机(UMT-2)探究转速、载荷、质量分数对润滑液润滑特性的影响。结果表明:HEC可以与水分子形成中、高强度的氢键;转速变化在摩擦副入口处对润滑液的成膜过程产生影响,进入摩擦副的润滑膜可以保持稳定的润滑状态,摩擦因数随转速增大几乎不变;增大载荷,润滑液在摩擦副间分布更加均匀,提升润滑性能,摩擦因数随载荷增大而减小;随润滑液质量分数增大,摩擦因数先减小后增大,质量分数为1.00%时摩擦因数最小。提出羟乙基纤维素水基润滑模型,模型包括水分子层和水合羟乙基纤维素层,其中水合羟乙基纤维素层起主要作用。     

薄膜油润滑中电粘度效应影响研究

利用组合滑块油润滑试验考察了双电层的电粘度效应对薄膜润滑性能的影响，采用施加外加电场和添加添加剂两种方法以改变润滑剂中离子浓度进行试验研究。结果表明：双电层引起的电粘度效应对摩擦因数有明显影响，摩擦因数随着外加电场的增强而变大，当外电场增大到一定程度时摩擦因数开始减小；在离子浓度较小时，摩擦因数随着离子浓度的增加而增大，当离子浓度增大到一定程度时摩擦因数开始减小。     

织物纹理在润滑条件下摩擦学性能的研究

对涤纶织物表面的纹理进行摩擦学性能试验研究。将表面为斜纹、平纹、仿平的3种纹理的涤纶织物试样分别黏附在45#钢盘表面,与直径为4mm的GCr15销配副,分别在机油和石蜡润滑下,在UMT-Ⅱ销-盘试验机上进行试验,研究其在不同速度和载荷下的摩擦学性能。结果表明,不同纹理的涤纶织物,相对于光滑试样均能显著降低摩擦因数,但其需要相对较长的跑合时间才能进入稳定的摩擦状态;润滑液黏度较高时,带有斜纹纹理的涤纶织物摩擦因数最低,润滑液黏度较低时,带有仿平纹理的涤纶织物摩擦因数最低。     

氧化铝陶瓷在腐蚀环境下的摩擦磨损性能

研究了氧化铝陶瓷在HCl溶液、NaOH溶液和去离子水3种润滑介质下的摩擦磨损性能,获得其在不同滑动速度下的摩擦因数、磨损体积和表面形貌.结果表明:酸性环境抑制了硅和铝的氢氧化物膜的产生,导致在HCl溶液润滑下摩擦副的摩擦因数高,氧化铝陶瓷表面磨损严重;以NaOH溶液为润滑介质时摩擦副的摩擦表面成膜度最高,摩擦因数最低,...     

纳米添加剂润滑条件下GCr15/45#钢摩擦磨损性能影响

随着纳米科技的发展和对纳米材料功能特殊性的认识,纳米材料作为添加剂开始越来越多的应用到润滑和抗磨自修复研究中。利用PLINT NENE-7型磨损试验机,选用中石油兰州润滑油厂生产的中负荷工业闭式齿轮油L-CKC220作为润滑油,研究了纳米氮化钛,纳米氧化铝,纳米二氧化硅作为添加剂对GCr15/45#钢摩擦副摩擦磨损特性的影响。分析不同纳米材料对摩擦因数曲线、磨斑形貌(SEM)及EDX能谱分析图的影响。结果表明:3种纳米添加剂均能使摩擦副的摩擦因数明显降低。     

载流条件下银基复合材料-黄铜滑环摩擦副的摩擦学性能

采用粉末冶金方法制备一种银-铜-石墨-碳纤维复合材料,利用环块式摩擦磨损试验机对该复合材料和黄铜滑环组成的摩擦副在大气条件下进行载流摩擦磨损试验,分析不同速度下载流大小对摩擦因数、接触表面电阻、接触表面电噪声、磨损量的影响。研究结果表明,摩擦因数、接触电阻、磨损量随载流的增大而增大,接触表面电噪声与电流呈非线性关系;该银基复合材料与黄铜滑环摩擦副的磨损机制在纯机械摩擦磨损条件下主要为黏着磨损,在载流条件下为磨粒磨损,电弧产生的电蚀促进了磨粒磨损的发生。该银基复合材料与黄铜滑环摩擦副的电噪声符合相关标准,具有较高的可靠性。     

外加电场主动控制摩擦系数的试验研究

外加电场可以显著改变铁磁流体的摩擦系数,本文利用销一盘试验机进行了研究,结果表明,加电场作用前后ＢＨ－１铁磁液体的磨擦系数相对变化与电流以强度关系密切,而对法向载荷、线速度和添加剂含量的变化不敏感。在正反电场的作用下,摩擦系数的最大变化率可达到３５％,而且变化过程具有可逆性。在研究电场对铁磁流体摩擦系数变化的影响的基础上,探讨了电流产生的静电场和磁场对摩擦系数的作用机下。     

外加电场对3种陶瓷/金属摩擦副摩擦行为的影响

使用自制面接触往复式滑动摩擦磨损实验机,采用质量百分比浓度为１％的硬脂酸锌水基乳化液作为润滑剂,研究了边界润滑状态下外加直流电场的几处施加方式对３种摩擦副在低速滑动时摩擦行为的影响。实验结果显示,外加电压的存在显示地改变了３种摩擦副的摩擦系数以及摩擦系数曲线的平稳程度,摩擦系数是最大相对增加量和最大相对减少量分别达到２００％和４０％。摩擦系数的改变与外加直流电压的通断是对应的,不同摩擦副对电压接通     

Laboratory evaluation of anti‐fretting lubricants

To characterise the friction and wear behaviour of materials and lubricants under a variety of operating conditions, laboratory models are frequently used to provide useful information. For example, during the development and/or selection of tribomaterials and lubricants, laboratory ranking of candidate products can save many hours of field testing. A reciprocating ball‐on‐flat wear test rig has been developed to rank the performance of materials, surface coatings, and lubricants under boundary, extreme‐pressure, or fretting conditions in a variety of environments and at various temperatures. The rig design is based on ASTM G133–1995. The friction force and wear are measured on both specimens while the load, stroke length and frequency, test temperature, lubricant type, test duration, surface topography of both ball and flat specimens, specimen materials, and environmental conditions are noted. The results presented in this paper refer specifically to a series of tests performed to evaluate various anti‐fretting lubricants. Two lubricants are compared in terms of friction coefficient and wear volume over time. A clear difference is shown between the two products.     

EHL Properties of Polyalkylene Glycols and Their Aqueous Solutions

Polyalkylene glycols (PAGs) are a type of synthetic lubricants widely used as compressor lubricants, gear oils, hydraulic fluids, and metal working fluids. The PAGs with typical molecular structure can dissolve in water, which makes it a candidate for the base stock of water-based lubricants. Till now, most of the investigations on the water-based lubrication have focussed on the additives. In this work, the potential of PAGs aqueous solutions to replace water as base stocks has been investigated. Four types of PAGs with different molecular weight and their aqueous solutions with different concentrations were studied to reveal their elastohydrodynamic lubrication (EHL) behavior. It has been found that the PAGs solutions can form EHL film like traditional oils. The film-forming capability depends on the viscosity, the pressure–viscosity coefficient, and the molecular weight of PAGs. The results indicate that the PAGs aqueous solution can be employed as base stocks of water-based lubricant.     

Effects of external electric fields on frictional behaviors of three kinds of ceramic/metal rubbing couples

In this paper, effects of external electric fields on frictional behaviors of Al₂O₃/brass, Al₂O₃/stainless steel and Al₂O₃/carbon steel couples under boundary lubricating conditions were studied on a self-made plate/plate type tribotester. Emulsion of 1 wt% zinc stearate dispersed into deionized water was used as lubricant in the experiments. The experiment results have shown that external electric fields affect the friction coefficient and its fluctuation of each rubbing couple substantially. The three couples showed different rates of change in friction coefficient and different tendency of change as the field was turned on and off during the rubbing process. Results acquired from experiments carried out in a wide range of external voltage, from 0 to 110 V, indicating that friction coefficient of Al₂O₃/brass couple increases monotonously with the intensity of the external electric field, although no linear relationship was found between them.     

Effect of applied voltage on friction and wear characteristics in mixed lubrication

The effect of an electric field applied between rubbing surfaces on friction and wear characteristics was examined using a ballon-disc testing apparatus under different lubrication conditions. The lubrication conditions were changed by changing the viscosity of the lubricants. By applying an electric field between the rubbing surfaces, the oxidation of the rubbing surface at the anode side is enhanced, and suppressed on the cathode side surface. The oxide film formed on the anode surface being harder than the bulk steel, the rubbing surface at the anode side was little worn, but that at the cathode side was abrasively worn. This wear characteristic could be utilised to attain favourable running-in. The application of an electric field, however, is considered to promote the breakdown of any EHL film formed. Therefore the effect of the application of an electric field between rubbing surfaces is influenced by the lubrication condition that is being tested.