纳米石墨颗粒在矩形件拉深成形过程中的摩擦特性研究

以石墨颗粒作为固体润滑剂及液体润滑剂的添加剂,在不同的润滑状态下进行了板料拉深成形物理试验,运用探针测试技术实时测试了矩形件的不同变形部位在拉深成形过程中所产牛的摩擦冈数大小及分布状况,评估纳米石墨颗粒作为润滑添加剂在矩形件拉深成形中的实际摩擦特性及润滑效果.研究表明纳米石墨颗粒作为润滑添加剂对板料拉深成形性能的影响显著.     

一种新型混合润滑剂及其摩擦特性的研究

混合润滑剂是一种新型润滑剂,它具有液体、半流体、固体润滑剂的综合优良特性.该种润滑剂能够在恶劣工作环境下具有良好的润滑性能.而且由于它的制作简单,成本较低,因此具有很好的应用前景.作者研制了十种配方的润滑块,并对其摩擦特性进行了实验研究.     

润滑添加剂和表面处理对轴承合金—钢边界磨损特性的影响

该项目从摩擦学系统工程原理出发,强调轴承合金的边界摩擦磨损特性不是轴承材料单独的材料性能,而是轴承材料—润滑剂—轴颈材料这一系统的特性。从轴承合金—钢(表面处理)—润滑剂(添加剂)这一摩擦学系统的优化组合上去寻求提高滑动轴承摩擦副在边界润滑条件下的摩擦学性能的新途径。     

纳米粗糙间隙中季戊四醇四酯的薄膜润滑行为

采用分子动力学模拟方法建立光滑和粗糙2种固体壁面结构，研究季戊四醇四酯润滑剂在不同压力、薄膜厚度下，在恒定剪切速度和温度下的薄膜润滑行为。分析壁面间润滑薄膜的密度分布，以及剪切过程中润滑剂的速度分布。输出固体壁面在x向和z向的力学响应，并计算摩擦因数。结果表明：表面纳米结构降低了润滑薄膜的厚度，减弱了润滑薄膜分层现象；当润滑薄膜厚度较大时，V形纳米沟槽有助于减小薄膜润滑系统的摩擦因数；润滑薄膜厚度较小时，V形纳米沟槽表面润滑状态容易从流体润滑转变到边界润滑状态，摩擦因数增大。     

基于Carreau流变模型的渐开线齿轮摩擦因数研究

结合载荷分担概念和弹流润滑理论,研究润滑剂的流变性对渐开线齿轮油膜厚度、摩擦因数等润滑特性的影响;分别采用Carreau流变模型和Doolittle-Tait自由体积黏度模型描述润滑剂的剪切稀化特性及黏压关系,研究齿轮载荷、转速、表面粗糙度和润滑剂压黏系数对摩擦因数的影响。研究结果表明:不同的润滑剂剪切稀化特性不同,因此油膜厚度、油膜承载比例和摩擦因数均不同;摩擦因数随着转矩的增大先显著增大,当超过某一转矩值时,摩擦因数开始缓慢变化;摩擦因数随着转速的增加先显著减小,当转速增加至某一值时摩擦因数又随之增大;随着表面粗糙度和润滑剂压黏系数的增大,摩擦因数均明显增大。     

润滑剂摩擦因数测试方法初步探讨

目前常用的润滑剂摩擦因数四球测定标准ASTMD5183-2005和SH/T0762-2005方法误差较大。分析测试误差的可能来源和标准方法中存在的问题,对润滑剂摩擦因数测试方法提出建议。测试系统误差是数据误差的重要来源,其中加载系统和扭矩测试系统可能是试验误差的主要来源,可通过深入的误差分析、实验标定或改进设计来保证试验机的测试精度和数据可靠性;润滑剂的摩擦特性是和润滑状态有密切关系的,可以用Stibeck曲线来比较全面地反映和评价润滑剂的摩擦特性。     

润滑剂对轮轨摩擦与磨损的影响

利用MMS-2A磨损试验机模拟轮轨系统在润滑油、二硫化钼锂基脂、植物油和石墨钙基脂4种润滑剂润滑下的摩擦与磨损行为,研究润滑剂对轮轨副摩擦、磨损特性的影响.结果表明:与干态相比,4种润滑剂均使摩擦副的摩擦因数减小,表面磨痕深度减小,磨损量降低,其中石墨钙基脂的减摩和抗磨效果最好;试验结束后,轮轨试样接触表面的硬度均有不同程度的增加,其中涂有石墨钙基脂的轮轨试样的表面硬度增加最小.     

影响井下防喷器胶筒与套管间摩擦因数的因素

通过摩擦试验,研究了正压力、相对滑动速度以及润滑条件对井下防喷器胶筒与套管间摩擦因数的影响。结果表明:相同正压力下,无润滑剂和水润滑摩擦时,两者间的摩擦因数随着滑动速度的增加而增加,在油润滑时,滑动速度的增加有利于润滑膜的形成,使摩擦因数降低;在相同正压力和相对滑动速度下,油润滑摩擦因数均值最小,水润滑时次之,无润滑剂时最大;正压力的影响无规律性。     

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。     

滚动轴承的纳米材料润滑技术

纳米材料润滑是一种改善轴承滚动表面性能的新技术。介绍了纳米材料的结构特性及其润滑机理，研究表明，纳米材料润滑剂可以在摩擦表面形成润滑薄膜，可以减小摩擦系数、填补与修复摩擦表面的某些缺陷，有益于解决滚动轴承的许多工作性能问题，如摩擦磨损、摩擦力矩与噪声等。     

Effect of lubricants on the friction and wear of Al2O3 against gray cast iron

The tribological behavior of ceramic Al₂O₃ coupled with gray cast iron (PHT) with different lubricants was investigated using a ring-on-block wear tester. In the wear test, air, distilled water, emulsion and oil were used as lubricants respectively in order to check the lubricating effectiveness of lubricants and the friction mechanism of solid graphite in the cast iron. Wear testing of 0.8% C steel (T8) sliding with Al₂O₃ was also carried out to compare with the test using gray cast iron. From these data the tribological behavior of graphite in the iron can be evaluated. The results show that the friction and wear of tested couples are decreased using different lubricants in the following order: air, distilled water, emulsion and oil. When lubricating with air and water, graphite in the iron as solid lubricant can decrease the friction and wear of the couples. However, when lubricating with emulsion and oil, graphite does not show the advantage of decreasing friction and wear.     

Effects of lubricants on friction and wear of Ti(CN)/1045 steel sliding pairs

The friction and wear properties of Ti(CN)/1045 steel rubbing pairs were investigated under dry and lubricated conditions by using a pin-on-disk tribometer. The selected speed range was 0.8 to 3.2 m/s and the load range was 58.8 to 235.2 N. Distilled water and a mineral oil (no additives) were used for lubrication, respectively. The wear of Ti(CN) ceramic under dry conditions was caused mainly by adhesion between the rubbing surfaces and the microfracture of Ti(CN). With the load and speed increasing, the adhesion and diffusion between rubbing surfaces increased and resulted in wear increasement of Ti(CN). Because of the brittleness of ceramics, the microfracture wear of Ti(CN) increased rapidly when the load was raised to some high values. The lubricating and cooling effects of the lubricants could improve the frict on and wear. Compared with water, oil was much better in improving the tribological properties. The analysis results obtained from XPS and AES examinations showed that ferrous oxide was produced on the wear scars, which could reduce the adhesion between the rubbing surfaces to some extent. The lubricating effects of the oil under boundary lubrication conditions were attributed to the formation of carbon films on the rubbing surfaces.     

The tribological performance of DLC-based coating under the solid–liquid lubrication system with sand-dust particles

Combination of solid and liquid lubricants to meet emission or environmental requirements of future tribological systems while providing the levels of desired friction and wear performance have received considerable research attention in the near term. The aim of the present work was to investigate the tribological behavior of oil-lubricated (PAO, PFPE, SO, IL and MAC) DLC coated surfaces under the conditions without and with sand-dust particles. The effects of applied load, frequency, and sand-dust particles on the tribological performance of DLC coating were systemically studied. The analysis results showed that solid–liquid lubricating coatings including SO and IL exhibited excellent anti-friction (～0.026) but relative poor wear-resistance performances under the conditions without and with sand-dust environments. But for PFPE and PAO, they demonstrated the worst tribological behaviors with high friction coefficient and wear rates. The added sand-dust particles lead to the wear rates to the one order of magnitude large than that without sand-dust conditions for all the selected liquid lubricants. The viscosity, contact angle and work of adhesion played an important part in affecting the tribological performances. The lubrication regimes in Stribeck curve for the five kinds of liquid lubricants were affected obviously by the sand-dust particles in different way. The formed transfer films on the coating surface and pin have much influence on the tribological behavior and the transition between lubrication regimes.     

Experimental investigation of porous bearings under different lubricant and lubricating conditions

The performance of porous bearing under different lubricants and lubricating conditions was experimentally investigated in this study. In order to carry out the experiments, a new test rig was designed to determine the tribological properties of based sintered bronze journal bearings that were manufactured by powder metallurgy (P/M) techniques. To determine the effects of lubricating conditions with and without oil supplement (OS) on the tribological characteristics of these bearings under static loading and periodic loadings, some experiments were carried out using different lubricants. In the tests, pure base oil (SAE 20W50), two fully formulated commercial engine oils (SAE20W50) and lubricating oils with commercial additive concentration ratio of3% were used. The worn surfaces of test bearings were examined using optical microscopy. Experimental results showed that the change in friction coefficient was more stable and in smaller magnitude under static loading than that of periodic loading. In addition, the friction coefficient and the wear rate conducted with base oil resulted in higher values than those of fully formulated oils with and without OS lubricating conditions. The experimental results obtained in this study indicated that the correct selection of lubricant and suitable running conditions were very important on the tribological characteristics of porous bearings.     

水溶性硼酸酯的摩擦学性能研究

利用四球机和环块试验机考察了一种水溶性硼酸酯在水中的摩擦学性能 ,并用X射线光电子能谱仪 (XPS)和电子探针 (EPMA)对摩擦表面进行了分析。摩擦学试验表明 :水溶性硼酸酯在水中具有良好的润滑性能和承载能力。表面分析证明元素S ,N和B在磨斑表面分布比较均匀 ,且B和S元素发生了摩擦化学反应。水溶性硼酸酯的抗磨作用机理是其在摩擦过程中发生了摩擦化学反应 ,生成了含硼酸、三氧化二硼、有机氮、二硫化亚铁、硫酸亚铁及摩擦聚合物等的复合膜 ,有效地提高了水基液的减摩抗磨性能     

表面粗糙度对纳米润滑添加剂摩擦学性能影响的研究

摩擦学系统的复杂性及多变性增加了对材料在摩擦试验过程的预见性的难度，通过XP销盘摩擦磨损试验机分别考察了钢／钢摩擦副住不同润滑介质中不同的表面粗糙度对其摩擦系数和磨损量的影响。试验结果表明：表面粗糙度对摩擦副的摩擦学影响是复杂的，在特定的润滑条件下，不同的表面粗糙度表现出不同的摩擦学性能。     

The effect of lubricants on tribological characteristics of fibrous materials

The questions of the changing tribological characteristics of filament yarn using lubricants have been discussed. Handling polyester filament yarn with lubricants based on polyethylene glycol PEG-400 allows one to change their friction and electrophysical properties due to the formation of the molecular boundary layers. The area of desired tribological characteristics for polyester filament yarn treated with experimental lubricants has been determined.     

The influence of lubricants on cam failure

This paper studies the effects of lubricants on the failure and reliability of cams. Experimental investigations of the influence of lubricants on cam failure have been carried out at a metalworking factory. This paper presents following:

– A classification of industrial oils for cams. To establish this classification, two essentials of parameters have been taken into account: the environment (ambient temperature) and the cam operating conditions (load and sliding velocity).

– A flowchart of lubricating oil selection procedure for cams as a function of all relevant influencing factors.

– An analysis of the symptoms and the causes of failure of machine tool cams.

– An analysis of the average life and curves of cam reliability of machine tools as a function of tribological properties of some industrial oils.

The obtained results have proved that the tribological properties of lubricants has a great influence on:

– reduction of failures,

– extension of the life and

– increase of the reliability of cams.

     

N-酰基苯丙氨酸的合成及其在水基中润滑和防锈性能研究

将脂肪酸酰氯和苯丙氨酸在碱性溶液中反应得到的N-酰基苯丙氨酸，用红外光谱对其结构进行表征；用四球摩擦磨损试验机考察了N-酰基苯丙氨酸以三乙醇胺为助溶剂时在水溶液中的摩擦磨损性能，并用俄歇电子能谱研究了磨斑表面边界膜的化学组成和元素分布。结果表明：N-酰基苯丙氨酸的水溶液表现出很好的抗磨和减摩特性，这可能是N-酰基苯丙氨酸三乙醇胺盐中的极性基团吸附在钢球的表面，长碳链疏水性的烃基在金属表面形成较厚的保护膜，在较高载荷运行下，发生化学反应形成高强度的摩擦化学反应膜；N-酰基苯丙氨酸三乙醇胺盐还有较好的防锈性。经细菌试验表明其具有较好的抗菌能力。     

纳米铜粉作为润滑油添加剂的性能研究

利用MMW-1型和MS-800型试验机,研究了纳米铜粉添加剂对润滑油摩擦学性能和承载能力的影响.结果表明润滑油中添加纳米铜粉可以降低摩擦,减少磨损,并可提高润滑油的承载能力.添加纳米铜粉的润滑油更能适应高速重载和瞬时失油等恶劣工况.