Tribological properties of sulfurized-nitrided layer prepared by a two-step method

The tribological properties of nitrided layer and sulfurized-nitrided layer of AISI 4135 steel were investigated under oil lubrication, and the layers were prepared by the ion nitriding treatment and a two-step method as the ion nitriding plus sulfurizing duplex treatment, respectively. A ball-on-disc friction and wear tester was adopted to evaluate the tribological performance. Scanning electron microscope (SEM), scanning Auger microprobe (SAM) and X-ray photoelectron spectroscope (XPS) were used to identify the morphologies and chemical compositions of the treated layer and the worn surface. It was presented that the sulfurized-nitrided sample with a thin FeS layer possessed much better tribological behaviors than the nitrided sample, including load carrying capacity, wear resistance, friction reduction and duration time. The mechanism was supposed that the decomposed activated S atoms of FeS layer promoted a new FeS chemical reaction film formation, which induced to the thin FeS layer playing as a solid lubricant for a longer time.     

Tribological mechanism and property of 9Cr18 friction pair at atmosphere and in vacuum

In this paper, the comparative tribological property of 9Cr18 friction pair used for aerospace components was investigated using a ball-on-disc tester in four different service conditions: in air, in vacuum, and with or without MoS₂-based film. The results indicate that the friction coefficients of the 9Cr18 couplings with MoS₂ solid lubrication or in vacuum are much lower than those in the conditions of dry friction or atmosphere, with relatively flat ground trace surfaces. While the friction coefficients of usual materials of friction pairs in vacuum are higher than those in atmosphere, it is shown in our study that the abnormal performance may be induced by the surface hardenability of dry friction transition and the lubrication effect of the MoS₂-based film. At the same time, the tribological mechanism of the pair is considered as well.     

离子硫化层与热喷涂硫化层的摩擦学性能比较

分别采用低温离子渗硫和等离子喷涂的方法在45^#钢表面制备了硫化层。在摩擦磨损试验机上对比研究了这两种硫化层在油润滑条件下的摩擦学性能。利用XRD分析了硫化层的相结构，用SEM观察了硫化层的表面及磨面形貌并进行了能谱分析。结果表明，各硫化层的摩擦学性能明显优于原始基体表面，其中离子硫化层的减摩性和耐磨性更好，耐热喷涂硫化层的抗擦伤性更佳。造成这种差别的主要原因在于两种硫化层的成膜机理不同。     

富勒烯和碳纳米管在润滑体系中的研究进展

纳米材料改善润滑体系是摩擦学研究的热点之一.综述了富勒烯和碳纳米管改善流体润滑体系、固体润滑体系(固体膜、碳基、聚合物基、金属基、陶瓷基润滑体系)摩擦性能的研究进展.富勒烯和碳纳米管可使体系的摩擦系数减小、磨损率减小、硬度增大,从而优化摩擦性能.富勒烯和碳纳米管具有优良的自润滑性,有成为"分子滚珠(轴)"润滑添加剂的潜力.     

颗粒间摩擦对颗粒流润滑影响的力学机制

颗粒流润滑是一种可用于苛刻工况环境的新型润滑方式,颗粒间摩擦对颗粒流润滑影响的规律和特性是阐明颗粒流润滑理论的关键科学问题,也可以为极端工况环境下颗粒流润滑轴承的设计和参数选择提供技术支持。为了分析颗粒间摩擦对颗粒流润滑系统宏、微观特性以及下摩擦副与颗粒润滑介质间摩擦的影响规律,构建了颗粒流润滑离散元数值模型,并对该问题进行了分析和研究。研究结果表明:颗粒间摩擦对颗粒流润滑系统的减摩润滑特性具有显著影响,下摩擦副和颗粒润滑介质之间的平均摩擦系数会随着颗粒间摩擦的增大而增大;颗粒流润滑系统内的微观配位数和滑动率均随着颗粒间摩擦系数的减小而增大;颗粒润滑介质在摩擦副间隙的宏观流动行为具有明显的分层特性,且宏观流动速度随着颗粒间摩擦的增大而减小,进一步的分析结果表明:颗粒润滑介质的波动速度是直接反映其宏观流动速度快慢的关键性参数。     

Ti+注入H13钢的注入层研究

Ti (10 0kV ,3× 10 17cm- 2 )注入H13钢 ,表面注入层的化学组成和微观结构发生了很大的变化。俄歇分析表明 ,注入元素Ti在钢表面层的剖面浓度分布呈近似高斯分布 ,在 4 0nm处Ti的浓度达到最大值。离子束真空碳化导致在钢的表面形成一层约 2 0nm的“富碳层”。透射电镜分析表明 ,表面层的微观形貌由注入前的板条状马氏体结构转变成注入后的微胞状结构。电子衍射则证实 ,表面注入层已出现非晶化 ,并且有约 5nm的TiC颗粒析出。摩擦磨损实验进一步表明 ,注入后钢的摩擦系数降低 70 % ,磨损率降低 98%。     

Experimental analysis of nanomechanics of spherical titanium oxide nanooils in reducing friction

This work explores the nanomechanics of sphere titanium oxide nanooils in reducing friction between two pieces of cast iron. A friction test is performed using an ATE-77 Reciprocal Tribological Tester made by Cameron-Plint Tribology Limited, England. The friction between two pieces of cast iron was determined 25-135 degrees C using home-made titanium oxide nanooils. In elastohydrodynamic lubrication (EHL), the lubricant is subjected to enormous pressures, there is considerable local heating, and the assumption of constant viscosity no longer holds up. The derivation of the governing equations for elastohydrodynamic lubrication, the pressure and temperature dependence of viscosity is recognized after the lubrication thin film approximation has been made. The viscosity of the nanooils consistently exceeded that of the paraffin oil enlarging the partial EHL area with a complete lubricating film between two move iron surfaces. The spherical geometry of TiO2 nanoparticles caused them to act as a rolling medium when the machine parts move which is in the solid friction area. Because they provide a rolling function, spherical titanium oxide nanoparticles have feasible tribological and lubrication applications in the mechanical industry to reduce noise, vibration and friction wear.     

SiC-Si合金化复相陶瓷干摩擦磨损性能的研究

在SiC-Si中加入Ni、Ti或B4C形成SiC-Si-Ni、SiC-Si-Ti及SiC-Si-B等复相陶瓷材料。研究了不同温度下的干摩擦磨损行为与机理。探讨了在摩擦表面形成固体润滑与液体润滑,以改善摩擦磨损性能的两种途径在SiC-Si复相陶瓷上实现的可行性。结果表明,通过摩擦反应在表面形成固体润滑膜,是改善SiC-Si复相陶瓷干摩擦性能的有效途径。     

粘结PTFE基固体润滑涂层在油润滑下的摩擦学性能

为了使粘结固体润滑涂层广泛应用于高新技术领域,探讨了不同滑移速度和载荷下聚酰亚胺粘结聚四氟乙烯（PTFE）基固体润滑涂层干摩擦和油润滑时的摩擦磨损性能,并对涂层与油复合润滑的机理进行了初步探讨。结果表明：随载荷、滑移速度变化,该粘结固体润滑涂层千摩擦和油润滑下的摩擦系数均变化不大;油润滑下涂层的摩擦系数明显低于干摩擦下...     

The effect of ion plating on the friction and wear of Ti6Al4V alloy

The effect of noble metal ion plating on the room temperature friction and wear of Ti6Al4V was investigated. Sliding wear experiments were conducted on a linear displacement machine which enabled the determination of coefficient of friction at regular intervals. The wear experiments were performed between two titanium alloy surfaces with various ion plating and dry lubrication conditions. Test results showed that the extent of wear damage of the titanium substrate was directly related to the rate of increase of the friction coefficient and not to its value. The best wear protection was provided either by gold ion plating on one surface combined with MoS₂ lubrication or by gold ion plating on both surfaces. The former case yielded a very low friction coefficient while the latter yielded a very high one. Modes of wear were determined by scanning electron microscopy of sectioned wear specimens.     

Effect of ion irradiation in an Al90Fe2Ce8 metallic glass

Here the irradiation effect of an AlFeCe metallic glass under nitrogen ions was investigated. Ion irradiation induced crystallization can be observed in the studied metallic glass. The surface morphologies have been also examined by atomic force microscopy prior to and after ion irradiation. It is found that the surfaces have been smoothened after ion irradiation. The nanohardness and Young’s modulus of metallic glass increase after ion irradiation, which can be attributed to the formation of crystalline phases. The results obtained here clearly suggest that ion irradiation can be a useful method to tailor the microstructure and mechanical properties of metallic glasses.     

Effect of ion irradiation on the properties of carbon nanotube buckypapers

Optical, electrical and structural properties of argon (Ar) ion-irradiated buckypapers of multi-walled carbon nanotube (MWCNT) at various doses prepared by a vacuum filtration method were investigated. It was found that the direct current (DC) conductivity and absorption spectra in the visible range were decreased with an increasing Ar ion irradiation dose. A subsequent heating of nanotube buckypapers at 800 K in a vacuum at each irradiation dose improved the conductivity of buckypapers, whereas optical absorption was unchanged. Moreover, the graphite structure of MWCNTs was transformed to amorphous structure with an increasing Ar ion irradiation dose. The decrease of optical absorption and electrical conductivity of MWCNT buckypaper at room temperature can be ascribed to the increase of defects in the irradiated MWCNTs.     

PTFE微粉/CF改性PEEK复合材料的摩擦磨损性能

为解决核电水循环系统中鼓型旋转滤网驱动装置的耐腐蚀问题,本文研究了碳纤维和聚四氟乙烯微粉改性的聚醚醚酮复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能.通过机械共混、高温模压的方法,制备了不同质量分数的聚四氟乙烯(PTFE)微粉/碳纤维(CF)/二硫化钼(MoS_2)/聚醚醚酮(PEEK)复合材料.采用拉伸试验机和塑料洛氏硬度计测试其力学性能,采用摩擦磨损试验机测试了复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能,采用扫描电子显微镜对其摩擦表面形貌进行分析.结果表明:复合材料在水润滑和油润滑时摩擦系数及磨痕宽度均较小,但水润滑时摩擦系数波动幅度较大且磨痕宽度略高;复合材料在干摩擦条件下的磨损机制以磨粒磨损为主,伴有疲劳磨损,油润滑时摩擦面可形成连续的润滑膜而保持光滑,水润滑时水流冲刷破坏了摩擦面上固体润滑膜的稳定性;CF质量分数增加时,复合材料的洛氏硬度和压缩强度递增,压缩强度达到164 MPa,PTFE微粉质量分数增加时,复合材料的洛氏硬度和压缩强度递减;CF质量分数增加时,复合材料的干摩擦系数及磨痕宽度下降,PTFE微粉质量分数增加时,复合材料的干摩擦系数下降,达到0.17.     

The influence of surface roughness on the starved lubrication of ball bearings

Abstract

A theoretical analysis is made for starved lubrication of a rigid point contact under the influence of surface roughness. The results show that both the directional property and the standard deviation of the combined surface roughness can affect the load carrying capacity of the lubricant film as well as the friction on the solid surfaces. The combined effects of speed ratio of the contiguous surfaces and the roughness on starved lubrication are also obtained. The results show that the effects of surface roughness may improve the starvation a little, but that they are not remarkable. A regression equation is found for determining the critically starved lubricant inlet level. Such an inlet level can indicate the minimum limit of lubricant supplied quantity, and, beyond this limit, the load carrying capacity of the lubricant film will decrease sharply. In addition, experiments have been carried out to observe the starved lubrication of a ball rolling on a flat glass disc. It is shown that higher surface speeds may make the starved condition much worse.     

Effect of intense laser and energetic ion irradiation on Raman modes of Multiwalled Carbon Nanotubes

The effects of intense laser and energetic ion irradiation on Raman vibrational modes of Multiwalled Carbon Nanotubes have been investigated. The intensity ratio of D and G modes decreases with increase in laser power density and remains almost constant with decrease of laser power density. The intensity ratio of D mode to G mode for ion irradiated Multiwalled Carbon Nanotubes decreases at low fluence (4 × 10¹¹ ions/cm²) and increases further with increase in ion fluence. The results show that ion irradiation at low fluence and laser irradiation lead to purification/ordering of the nanotubes.     

润滑状态下线接触滑动粗糙界面的动摩擦特性研究

滑动粗糙界面的摩擦润滑特性对界面的润滑设计和润滑状态预测具有重要的理论和实际意义。本文通过建立不同润滑状态下的滑动粗糙界面模型,基于界面的法向载荷由润滑油膜和粗糙体共同承担的载荷分配思想,采用Greenwood-Williamson统计模型描述粗糙表面形貌,考虑界面润滑的时变效应和润滑油的粘-压特性,建立了线接触滑动粗糙界面的油膜厚度方程和粗糙体接触压力方程,获得了整个润滑区的润滑油膜载荷比例因子、油膜厚度和摩擦系数随滑动速度的变化关系,推导了界面由混合润滑过渡为液压润滑的临界速度关系表达式,分析了滑动粗糙界面的润滑承载机理,获得了界面油膜厚度、摩擦系数和临界速度随界面形貌参数、法向载荷、润滑油属性参数的变化规律,为机械结构的界面润滑设计、润滑状态预测和润滑优化提供理论和实验参考。     

真空-紫外辐照对SiO2/MoS2/酚醛环氧树脂涂层摩擦学性能的影响

为了研究真空-紫外辐照对润滑涂层的影响,采用地面模拟装置对添加SiO2前后的MoS2/酚醛环氧树脂涂层进行辐照,考察了辐照前后涂层的摩擦学性能.结果表明,真空-紫外辐照使涂层的摩擦系数、耐磨性分别呈降低、增强趋势.此外,SiO3的添加在一定程度上提高了复合涂层的摩擦学性能和抗紫外辐照性能.     

铌离子注入改善铝表面的力学性能

利用金属蒸气真空弧离子源,将大束流Nb离子注入到铝中,改善了铝表面的力学性能。在离子注入过程中直接形成了金属间化合物Al3Nb。金属间化合物的形成与离子注入的剂量有关。当Nb离子剂量达到3×10     

梯度自润滑复合材料在不同滑动摩擦下的摩擦学特性

梯度自润滑复合材料是一种新型润滑材料,利用粉末冶金工艺设计和制备了该材料,考察了其在不同摩擦条件下的摩擦学特性,并对其摩擦磨损机理进行了分析和研究.结果表明:梯度自润滑复合材料随着复合固体润滑剂含量的增多,摩擦学性能明显改善,但润滑剂含量过高将导致材料表面硬度过低;该材料适用于高载倚下的润滑部件;脂润滑条件下,复合固体润滑剂与润滑脂结合在摩擦面上形成的膏状润滑膜使梯度自润滑复合材料的摩擦学性能显著改善;在脂润滑高载荷条件下,梯度自润滑复合材料的磨损主要发生在磨损初期,之后磨损极小,摩擦系数也趋于减小.     

Enhancement of wettability and antibiotic loading/release of hydroxyapatite thin film modified by 100 MeV Ag ion irradiation

The effect of swift heavy 100 MeV Ag⁷⁺ ions irradiation was studied on hydroxyapatite (HAp) thin film prepared by pulsed laser deposition technique (PLD). The GIXRD analysis confirmed the absence of any phase in the HAp phase due to irradiation. In addition, there was a considerable decrease in crystallinity and crystallite size on irradiation. There was no significant variation in the stoichiometry of the irradiated films. Irradiation seemed to decrease the optical band gap energy of HAp thin films. The surface roughness, wettability and bioactivity were improved on irradiation of the samples. Amount of amoxicillin loading/release increased (10%) in ion beam irradiated (1 × 10¹² ions cm⁻²) sample. Irradiated sample showed fast rate of amoxicillin (AMX) release than the pristine. Bactericidal effect was found to increase on irradiation. Surface modified and antibiotics incorporated HAp coated titanium implants may be used to prevent post-surgical infections and to promote bone-bonding of orthopedic devices.