On the feasibility of using cryo‐treatment as a tool to enhance the abrasive wear behaviour of solid‐lubricated polymeric composites

Cryo‐treatment, a bulk modification technique, is fast emerging as a way with which to improve the wear resistance of metals. This technique has also shown the ability to enhance significantly the abrasive wear performance of some polymers and their short glass‐fibre reinforced composites. In this work, short carbon‐fibre reinforced composites of some heat resistant polymers, such as polyetherimide, polyethersulphone, polyamide 6,6, polyetheretherketone, and polytetrafluoroethylene, were selected to explore the potential of cryo‐treatment. The selected materials were cryogenically treated by cooling them to the temperature of liquid nitrogen. The abrasive wear tests were carried out at ambient temperature in single pass conditions at various loads, on a pin‐on‐disc machine, using silicon carbide paper as a counterface. The investigations revealed that this technique has definite potential to increase the wear performance of carbon‐fibre reinforced composites. An increase in hardness due to cryo‐treatment was thought to be responsible for an observed improvement in wear performance. However, the extent of improvement in the wear performance was not matched by an increase in the hardness value. Scanning electron microscopy proved useful in examining the morphological changes in the composites due to cryo‐treatment.     

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。     

The Effect of WS2 Nanoparticles on Friction Reduction in Various Lubrication Regimes

A study of the tribological behavior of nested inorganic fullerene-like (IF) nanoparticles of WS₂, as a potential additive to base oils is presented. Friction measurement results obtained from three different test rigs over a wide range of normal loads and sliding velocities are shown. Stribeck curves are used to reveal the lubrication regimes where the IF are most effective. It is found that the addition of IF-WS₂ nanoparticles to the base oils results in up to 50% reduction in friction coefficient in the mixed lubrication regime. The mechanism of improved friction and wear behavior with the IF additive is discussed.     

固体颗粒分布对轴承润滑的影响

基于格子-波兹曼方法 (LBM)理论,分析含固体颗粒的轴承润滑问题。通过建立润滑油的理论离散模型,分析固体颗粒分布对于油膜压力、润滑油流速的影响。分析结果表明:在油膜厚度方向分布的固体颗粒越多,颗粒的分布形式对润滑油流动的阻碍能力越强,则其对于油膜压力及油膜流动的影响也越大;当分布形式相同时,固体颗粒个数越多对油膜压力的影响越大;即润滑油中所含固体颗粒浓度越大,对润滑的影响程度也越大;无论分布形式如何,固体颗粒对于离颗粒较远的下游区域的速度影响较小。     

油润滑大pv值枢轴宝石轴承的摩擦学特性研究

对大 pv值枢轴宝石轴承在 8种矿物油及 3种合成润滑油作用下的摩擦学性能进行试验研究。结果表明 ,在矿物油润滑下 ,不同抗磨添加剂的枢轴磨损率顺序为 T3 0 6>Mo S2 >T3 0 9>T3 51 >T3 2 1 >T3 0 5>金微油>T3 61 ,其中 T3 0 6作用下轴承的摩擦扭矩为最大 ,T3 0 5与金微油作用下摩擦扭矩为最小 ;在氟醚油、氟氯碳油和聚乙二醇作用下 ,枢轴宝石轴承均可形成良好的吸附油膜 ,较矿物油相比 ,其摩擦力矩与磨损率呈较大幅度下降 ,其中尤以聚乙二醇的作用效果最为突出     

固体膜润滑剂耐燃油及摩擦学性能研究

通过系列耐燃油及摩擦学性能试验设计,模拟固体膜润滑剂在发动机燃油系统中的实际应用条件,对比研究满足MIL-PRF-46010标准的固体膜润滑剂(牌号A)、航空通用高温固体膜润滑剂(牌号B)以及航天用中温固体膜润滑剂(牌号C)在燃油系统中的耐燃油及摩擦磨损性能。结果表明:喷气燃料对A型固体膜润滑剂的影响不大,喷气燃料浸泡前后A型固体膜润滑剂的平均摩擦因数均在0.02~0.05范围内,耐磨寿命均在1 h以上;A型固体膜润滑剂与喷气燃料长期接触不会影响喷气燃料的性能;A型固体膜润滑剂材料不论是在承载能力、耐磨寿命还是耐燃油性能方面都明显优于B型及C型固体膜润滑剂,这是因为A型固体膜润滑剂中的MoS_2和Sb_2O_3起到了协同抗磨作用。     

Influence of Deposition Positions on Fretting Behaviors of DLC Coating on Ti-6Al-4V

Abstract

The influence of diamond-like carbon (DLC) coating positions—coated flat, coated cylinder, and self-mated coated surface tribopairs—on the fretting behaviors of Ti-6Al-4V were investigated using a fretting wear test rig with a cylinder-on-flat contact. The results indicated that, for tests without coating (Ti-6Al-4V–Ti-6Al-4V contact), the friction (Q_max/P) was high (0.8–1.2), wear volumes were large (0.08–0.1?mm³) under a large displacement amplitude of ±40 µm and small (close to 0) under a small displacement amplitude of ±20 µm, and the wear debris was composed of Ti-6Al-4V flakes and oxidized particles. For tests with the DLC coating, under low load conditions, the DLC coating was not removed or was only partially removed, Q_max/P was low (≤0.2), and the wear volumes were small. Under high load conditions, the coating was entirely removed, Q_max/P was high (0.6–0.8), and the wear volumes were similar to those in tests without coating. The wear debris was composed of DLC particles, Ti-6Al-4V flakes, and oxidized particles. The DLC coating was damaged more severely when deposited on a flat surface than when deposited on a cylindrical surface. The DLC coating was damaged more severely when sliding against a DLC-coated countersurface than when sliding against the Ti-6Al-4V alloy.     

飞机滑油系统故障分析

在分析飞机滑油系统工作原理的基础上，对某型飞机滑油系统中存在的一些故障，包括滑油变色或混有金属屑、滑油消耗量超过规定、系统漏油外部漏油、滑油箱油量增多、滑油箱油量减少等进行了分析，并相应提出了在使用和维护中应注意的问题，为航空机务维护实践提供有益的借鉴。     

Cryogenic Friction Behavior of PTFE based Solid Lubricant Composites

Solid lubricants used in aerospace applications must provide low friction and a predictable operation life over an extreme range of temperatures, environments and contact conditions. PTFE and PTFE composites have shown favorable tribological performance as solid lubricants. This study evaluates the effect of temperature on the friction coefficient of neat PTFE, a PTFE/PEEK composite and an expanded PTFE (ePTFE)/epoxy coating. These experiments evaluate friction coefficient over a temperature span which, to the investigators’ knowledge, has not been previously examined. Results show a monotonic increase in friction coefficient as sample surface temperature was decreased from 317 to 173 K for all three samples. The frictional performance of these and other published solid lubricant polymers was modeled using an adjusted Arrhenius equation, which correlates the coefficient of friction of the polymer materials to their viscoelastic behavior. A model fit of all the polymer data from 173 to 450 K gives an activation energy of 3.7 kJ/mol. This value suggests that breaking of van der Waals bonds is the likely mechanism responsible for the frictional behavior over this temperature range.     

烷氧基硼酸锌的动态固体膜润滑及零磨损特性的研究

提出了动态固体膜润滑的概念,合成了烷氧基硼酸锌,评价了其作润滑油添加剂的摩擦学性能,采用改进的环-块摩擦磨损试验机利用电阻法测定了摩擦副之间的润滑状态,利用扫描电子显微镜（SEM）观察了磨斑形貌。实验结果表明：当负荷低于40 N、摩擦速度高于1.28 m/s时,电阻测定表明摩擦副之间被添加剂（烷氧基硼酸锌）产生的半固体膜所隔开,处于动态固体润滑膜润滑状态,并可实现零磨损。SEM观察到的磨斑表面形貌进一步证实了动态固体润滑膜的存在。该添加剂表现出了一定的抗磨减摩性能。     

高温泵轴承失效分析及润滑可靠性监测系统的应用

某重油催化装置油浆泵采用集中油雾润滑方式,油液监测发现轴承润滑油中的金属元素含量高,并且呈急剧增加的趋势,拆机检查发现油浆泵轴承出现了严重磨损。分析该油浆泵轴承磨损原因,提出了采用稀油润滑和油雾润滑组合方式来改善轴承润滑。同时,采用了大型炼化企业机泵群油液监测平台对关键动设备进行状态监测,有效保证了设备长周期安全运行。     

固体润滑剂在切削加工润滑中的应用

在分析固体润滑机理的基础上 ,对国内外固体润滑剂在切削润滑中的应用进行了综合评述 ,指出了固体润滑剂在各种切削润滑方式中的作用和特点 ,指出了固体润滑剂在切削润滑中的值得重视的发展方向     

GCr15钢微织构表面固体润滑性能研究

为研究不同表面处理方式对PTFE/GCr15钢配副表面摩擦学性能的影响,采用Nd:YAG纳秒激光器对GCr15轴承钢下试样表面进行激光织构加工,并以纳米MoS₂固体润滑剂作为润滑介质,以黏结有PTFE自润滑衬垫的圆柱销作为上试样进行对摩试验。研究发现:PTFE自润滑衬垫与微织构GCr15摩擦副在干摩擦条件下摩擦因数较低,仅为0.137,而在纳米MoS₂固体润滑剂润滑条件下,其摩擦因数进一步下降为0.123,且波动较小。通过EDS分析表明,表面微织构、聚四氟乙烯衬垫与纳米MoS₂润滑介质三者具有协同润滑减摩效应,可摩擦副表面生成一层由PTFE与纳米MoS₂材料组成的致密、平滑复合润滑膜,有效改善对摩副之间的润滑特性。研究表明,通过表面激光织构技术与固体自润滑技术(添加纳米MoS₂)的有效集成融合,可进一步改善PTFE/GCr15钢配副的润滑性能。     

齿轮径向自吸流体润滑方法的供油分析

针对齿轮传动的乏油现象,提出了一种新型的齿轮径向自吸流体润滑方法,从润滑与冷却两方面对整个啮合过程进行了供油的理论分析与计算。分析表明:螺杆泵的单导程容积大小受到与其同构件的齿轮转速与载荷的限制;冷却散热对螺杆泵单导程容积的影响与转速无关;螺杆泵单导程容积的设计应该按啮合过程中供油量的最大值设计。     

二硫化钼基润滑涂层在润滑油中的作用机理及实际应用

讨论了在几种液体润滑介质(液体石蜡、10^#机油、HM46液压油)中，涂敷FM-510二硫化钼基润滑涂层的摩擦副的摩擦磨损性能和润滑机理。试验机评价和台架考核结果表明，在润滑油中，涂敷FM-510涂层的摩擦偶对能够协助流体润滑膜的形成并维持流体润滑状态。扫描电镜观察涂层和对偶的微观表面，用能谱分析表面元素组成，揭示了其作用机理：干摩擦条件下，二硫化钼基润滑涂层与金属对偶表面的相对滑动，形成了以Mo、S、Sb为主的转移膜，但在润滑油介质中没有形成这类转移膜；二硫化钼基润滑涂层的表面有大量的、均匀分布的、直径小于3μm的孔穴，起到了蓄油作用，更易于建立流体润滑条件，形成均匀分布的油膜。     

超固体润滑及其在微机械电子系统中的应用前景

介绍了超固体润滑的概念 ,综述了超固体润滑的研究现状和近年来的研究成果 ,通过对微机械电子系统摩擦学问题的讨论 ,分析了超固体润滑在微机械电子系统中应用的前景 ,阐述了超固体润滑技术在微机械电子系统中应用的发展趋势     

Lubrication of high temperature ceramic materials

A composite of CaF₂/BaF₂/Ni was shown to be an effective lubricant for a silicon carbide ceramic and a titanium carbide/nickel cermet when tested as like pairs in crossed cylinders geometry at room temperature and at 600°C.     

Friction and wear characteristics of ion-beam modified graphite coatings

Solid lubricated surfaces are now widely used in the tool industry, and the new concept of ‘soft tools’ recently introduced has emphasized low-friction surfaces. The present paper deals with a novel ‘burnishing’ process based on ionic bombardment of powder graphite coating/substrate systems. This process may influence both the coating and the coating/substrate interface, and it is effective for improving lubrication even at low doses of bombarding ions. The present study will discuss the friction and wear properties of graphite-powder coatings on a silicon wafer bombarded with 200 keV ion beams of argon, nitrogen and hydrogen ions, the last two as molecular ions. The coefficients of friction and wear rates of the coatings were found to be strongly dependent on the ion-bombarding species and ion dose. The argon ion bombardment increased the coefficient of friction and wear rate of the powder coating. However, at the interface of the silicon substrate, the ion-induced burnishing improved the tribological behaviour of the silicon material. Bombardment with nitrogen and hydrogen ions showed a marked improvement in the tribological properties of the graphite powder coating. Thus a reduction in wear rate by three orders of magnitude was observed in the case of nitrogen, and for both ions it was noted that ion-beam burnished graphite was lubricating in a dry environment, which has not been reported previously. The perspectives of ion bombardment as a burnishing process will be discussed and the observed effects will be qualitatively explained in the context of the theory for ionic penetration into solids.