润滑油中加入纳米氧化铝对缸套-活塞环摩擦副摩擦磨损特性的影响

在普通CD40润滑油中加入纳米氧化铝,研究了在不同载荷条件下对缸套活塞环摩擦副摩擦磨损特性的影响;用铁谱仪对试验油样进行了磨粒分析;用原子力显微镜对缸套试样表面的微观形貌进行了测试;用LAS-3000型表面分析系统对磨损表面进行了成分分析。结果表明：缸套活塞环摩擦副在含纳米氧化铝的润滑油作用下,表现出优越的抗摩减磨性能,其效果随栽荷的增大而增强;在高载荷作用下缸套试样表面形貌有了明显的改观,减小了摩擦阻力,降低了摩擦因数。     

Tribological studies of coated pistons sliding against cylinder liners under laboratory test conditions

The presence of coatings and surface topography play an important role in the tribological performance of sliding components. Depending on the coating used, it is possible to reduce friction and/or reduce wear. However, although there may be low friction and wear‐resistant coatings suitable for use in pistons, some coatings may hinder the tribological performance by changing the lubrication regime or by preventing additives from their intended function through chemical mechanisms. In this work, piston skirt segments extracted from a commercial aluminium alloy piston were coated with a diamond‐like carbon (DLC) coating, a graphite–resin coating or a nickel–polytetrafluoroethylene (Ni–PTFE) coating and were tribologically tested using a reciprocating laboratory test rig against commercial grey cast iron liner segments. The tribological tests used commercial synthetic motor oil at a temperature of 120 °C with a 20 mm stroke length at a reciprocating frequency of 2 Hz. Results showed that the graphite–resin coating, although it may serve as a good break‐in coating, wears rapidly. The Ni–PTFE coating showed friction reduction, whereas the DLC coating wore off quickly due to its small thickness. Furthermore, the higher hardness of the DLC coating relative to the cast iron liner surface led to pronounced changes on the liner counterface by polishing. In contrast with the uncoated piston skirt segments, all of the coatings prevented the formation of a visible tribochemical film on the cast iron surface. Copyright © 2012 John Wiley & Sons, Ltd.     

Influence of Surface Groove Width on Tribological Performance for Cylinder Liner–Piston Ring Components

Surface groove width is of great significance to the performance of the cylinder liner–piston ring (CLPR) with the different surface textures in marine diesel. However, little is understood about the specific application (e.g., the geometric parameters of surface textures and operating conditions) of surface texture in actual marine diesel engines. To address this issue, different surface groove textures including grooves structures with 1-, 2-, 3-, and 4-mm widths were designed based on previous results related to marine diesel engine applications. A series of experimental tests was conducted in a reciprocation tester, and data on the friction characteristics were obtained under different operating conditions. Comparative studies on the friction coefficients, worn surface features, and oil film characteristics were performed. Results showed that the 2-mm groove structure of the cylinder liner was more favorable for improving the wear performances at low speed, whereas a 3-mm groove structure of the cylinder liner was more suitable for improving the wear performance at higher speeds, though its wear performance needs to be improved under high load. These results help to understand the specific application of surface texture on the wear performance of the CLPR pair.     

Topographic features of cylinder liners — an application of three-dimensional characterization techniques

Studies of wear patterns on engine cylinder liners show that radial wear is greatest on the anti-thrust side, and close to top dead centre. As a result of this wear, surface topography features at different positions exhibit different characteristics. Quantitative representation of the features is helpful for functional analysis and functional control of cylinder liner manufacture. In this paper three-dimensional characterization techniques are applied to produce a comprehensive characterization of cylinder liner wear at different longitudinal positions. The areal autocorrelation function and the areal power spectrum reveal the changes in topographic features. The different topographic features of newly created, after running-in, severely worn and bore polished surfaces of cylinder liners are identified by quantitative functional indices. The characterization techniques and parameters used in the paper constitute an effective approach to the characterization of surface topography of cylinder liners and other tribological surfaces.     

Running-in wear of a compression ignition engine: Factors influencing the conformance between cylinder liner and piston rings

The conformance between the liner and rings of an internal combustion engine depends mainly on their linear wear (dimensional loss) during running-in. Running-in wear studies, using the factorial design of experiments, on a compression ignition engine show that at certain dead centre locations of piston rings the linear wear of the cylinder liner increases with increase in the initial surface roughness of the liner. Rough surfaces wear rapidly without seizure during running-in to promote quick conformance, so an initial surface finish of the liner of 0.8 μm c.l.a. is recommended. The linear wear of the cast iron liner and rings decreases with increasing load but the mass wear increases with increasing load. This discrepancy is due to phase changes in the cast iron accompanied by dimensional growth at higher thermal loads. During running-in the growth of cast iron should be minimised by running the engine at an initial load for which the exhaust gas temperature is approximately 180 °C.     

Tribological characteristics of one-process and two-process cylinder liner honed surfaces under reciprocating sliding conditions

This paper reports an experimental study of the effect of surface texture on cylinder liner wear. This research is important because the conjunction between piston rings and cylinder liner is one of the major sources to frictional losses in internal combustion engines. Experiments were conducted on a reciprocating tester. Specimens were cut from cylinder liners honed or plateau honed made of grey cast iron of hardness 218 HB. The honing operation was performed in order to obtain very similar values of the Sq parameter of one-process and two-process surfaces. In addition, one-process specimens characterised by different Sq parameter values were tested. Counter-specimens were made from chromium-coated steel C45. It was found that wear of two-process surfaces was lower than that of one-process surfaces characterized by the same Sq parameter. Linear wear of specimens was proportional to initial Sq parameter value. The effect of additional oil pockets created by the burnishing technique on cylinder liner wear was negligible.     

激光微造型表面摩擦磨损性能研究

采用声光调Q二级管泵浦固体光源（DPSS）Nd：YAG激光器对缸套试件表面进行了,微造型州纹加工。在往复式活塞环-缸套摩擦磨损模拟试验机上进行了激光造型缸套试件与未造型光滑缸套试件的摩擦磨损性能对比试验研究。试验结果表明,在重载高速条件下,激光网纹试件与未造型试件相比,摩擦因数降低23％,磨损量降低66％。说明激光网纹沟槽具有贮油、积屑和动压润滑作用,同时激光加工的网纹淬火效应也有利于提高支承表面的耐磨抗擦伤性能。     

Ionic Liquids as Novel Lubricants and Additives for Diesel Engine Applications

The lubricating properties of two ionic liquids (ILs) with the same anion but different cations, one ammonium IL [C₈H₁₇]₃NH.Tf₂N and one imidazolium IL C₁₀mim.Tf₂N, were evaluated both in neat form and as oil additives. Experiments were conducted using a standardized reciprocating sliding test with a segment of a Cr-plated diesel engine piston ring against a gray cast iron flat specimen. The cast iron surface was prepared with simulated honing marks as on a typical internal combustion engine cylinder liner. The selected ILs were benchmarked against conventional hydrocarbon oils. Substantial friction and wear reductions, up to 55% and 34%, respectively, were achieved for the neat ILs compared to a fully formulated 15W40 engine oil. Adding 5 vol% ILs into mineral oil has demonstrated significant improvement in the lubricity. One blend even outperformed the 15W40 engine oil with 9% lower friction and 34% less wear. Lubrication regime modeling, worn surface morphology examination, and surface chemical analysis were conducted to help understand the lubricating mechanisms for ILs. Results suggest great potential for using ionic liquids as base lubricants or lubricant additives for diesel engine applications.     

Tribological evaluation of piston skirt/cylinder liner contact interfaces under boundary lubrication conditions

The friction and wear between the piston and cylinder liner significantly affects the performance of internal combustion engines. In this paper, segments from a commercial piston/cylinder system were tribologically tested using reciprocating motion. The tribological contact consisted of aluminium alloy piston segments, either uncoated, coated with a graphite/resin coating, or an amorphous hydrogenated carbon (a‐C : H) coating, in contact with gray cast iron liner segments. Tests were conducted in commercial synthetic motor oils and base stocks at temperatures up to 120°C with a 2 cm stroke length at reciprocating speeds up to 0.15 m s⁻¹. The friction dependence of these piston skirt and cylinder liner materials was studied as a function of load, sliding speed and temperature. Specifically, an increase in the sliding speed led to a decrease in the friction coefficient below approximately 70°C, while above this temperature, an increase in sliding speed led to an increase in the friction coefficient. The presence of a coating played an important role. It was found that the graphite/resin coating wore quickly, preventing the formation of a beneficial tribochemical film, while the a‐C : H coating exhibited a low friction coefficient and provided significant improvement over the uncoated samples. The effect of additives in the oils was also studied. The tribological behaviour of the interface was explained based on viscosity effects and subsequent changes in the lubrication regime, formation of chemical and tribochemical films. Copyright © 2010 John Wiley & Sons, Ltd.     

Tribological performance of three advanced piston rings in the presence of MoDTC-modified GF-3 oils

The piston assembly (piston ring and cylinder bore) is one of the key parts of the internal combustion (IC) engine. Its performance will directly determine the performance of the whole engine. The piston assemblys tribological performance will be influenced by both its mechanical properties and the tribochemical interactions that take place on their surfaces. In this paper, three kinds of advanced stainless steel piston rings with a single nitrided layer, CrN coating on the nitrided layer and a B₄C and CrN binary-layer coating on the nitrided layer, respectively, were employed. Their frictional behavior and wear performance, when sliding against the cast iron cylinder bore materials lubricated with two kinds of GF-3 category mineral-based engine oils (one of them blended with MoDTC friction modifier), were investigated on a SRV tribotester. The test conditions were set and maintained to simulate engine-operating conditions. SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray spectroscopy) were employed to characterize the morphology and elemental composition of the wear tracks. Tribotests and analysis results indicate that changes in both the mechanical properties of the tribomate (piston coatings) and tribochemical interactions (formulation of engine oils) have an impact on the tribological performance of the piston assembly. Tribochemical interactions will have a more obvious influence on friction coefficients while the mechanical properties of the tribomate have a more obvious influence on wear.     

Sliding wear response of a grey cast iron: Effects of some experimental parameters

This investigation pertains to the influence of some test parameters like applied load, sliding speed and test environment on the sliding wear behaviour of a grey cast iron. Properties studied were wear rate, frictional heating and friction coefficient in dry and oil lubricated conditions. The wear response of the samples has been discussed in terms of specific characteristics like load bearing, lubricating and cracking tendency of different microconstituents of the cast iron. Examination of wear surfaces, subsurface regions and debris particles has also been carried out to understand the operating wear mechanisms and further substantiate the observed response of the samples.     

The effect of cast iron graphites on friction and wear performance I: Graphite film formation on grey cast iron surfaces

Cast iron is assessed as a self-lubricating metal-base composite material. The formation of cast iron graphite films and the effective surface treatment of grey cast iron are discussed. It was found that the friction and wear behaviour of cast iron are influenced by the formation of a graphite surface layer. When cast iron surfaces are etched with Nital, they are found to be covered with a graphite film during the sliding friction process. This contributes to the protection of metallic contact points. The formation of graphite films during testing is assumed to be due to the non-elastic deformation of surface graphite. The effects of applied load, sliding velocity and lubricant are also discussed. The coefficient of friction increases with applied load and sliding velocity, and therefore lubrication becomes more important. These phenomena are discussed in terms of the formation of graphite films during the friction process.     

表面形貌对活塞环密封及摩擦性能的影响

综合考虑活塞环表面形貌、弹性变形、运动面型线影响,建立柴油机活塞环-缸套摩擦副的弹性流体动压润滑计算模型,分析活塞环表面纹理方向及粗糙度大小对活塞环窜气及摩擦功耗的影响。研究发现,随着转速的提升,活塞的窜气量及摩擦功耗会加剧,导致发动机效率降低;活塞环-缸套摩擦副的表面纹理方向影响窜气量和摩擦功耗,采用活塞环横向纹理和缸套纵向纹理配合时,对活塞环窜气量及摩擦功耗的改善效果较好;活塞环和缸套的表面粗糙度对密封和润滑特性有较大影响,当缸套表面粗糙度增大时,窜气量先减小后增大,摩擦功耗先增大后减小,而在一定范围内,当活塞环表面粗糙度增大时,窜气量和摩擦功耗都减小。     

Impacts of Friction-Modified Fully Formulated Engine Oils on Tribological Performance of Nitrided Piston Rings Sliding against Cast Iron Cylinder Bores

The tribochemical interaction in a nitrided piston ring/cast iron cylinder bore sliding contact with two commercial fully formulated engine oils (ILSAC GF-2 and GF-3 category, referred to as modified GF-2 and modified GF-3, respectively) supplemented with molybdenum dithiocarbamate (MoDTC) friction modifier was investigated in a laboratory bench test. Test results indicated that the modified GF-2 oil could produce a rapid friction reduction while the modified GF-3 oil maintained a stable and lower coefficient of friction (μ = 0.03) for a longer testing time. The modified GF-3 oil also generated a lower wear rate compared with the modified GF-2 oil under the same tribotest conditions. Based on SEM/EDX analyses of wear tracks on the tested tribo-components, it appears that the better formed tribofilm on both the lower and upper specimens by the modified GF-3 oil made a significant contribution to its tribological performance compared with the modified GF-2 oil when sliding under the same test conditions.     

Corrosion and wear resistance characteristics of NiCr coating by laser alloying with powder feeding on grey iron liner

To reduce the mixed fuel induced excessive wear of the cast iron engine cylinder liners, research on laser alloying of NiCr alloy with powder feeding was performed to locally change both the composition and the microstructure of the liner. The research indicated that laser alloying of 75Ni25Cr on grey cast iron liner demonstrates sound alloying layers free of cracks and porosities. The microstructure of the alloyed layer is composed of pre-eutectic austenite and ledeburite. The alloying element Ni is mainly located in the austenite, while Cr is mainly in cementite. The average hardness is HV_0.2500. The corrosion resistance of the alloyed layers in diluted H₂SO₄ solution and NaOH solution is dramatically improved compared to the grey cast iron. The relative wear resistance of the laser-alloyed 75Ni25Cr layer is 4.34 times of that of the grey cast iron. The improvements on the corrosion and wear resistance of the cast iron are attributed to the composition and microstructure change by laser alloying of 75Ni25Cr. Laser alloying can be a good solution to improve wear and corrosion resistance of the grey iron liners in mixed fuel environment.     

全配方发动机油SJ/5W-30中二烷基二硫代甲酸钼的摩擦学特性研究(Ⅱ)--二烷基二硫代甲酸钼(MoDTC)的摩擦化学效应

EDX分析表明，摩擦磨损过程中二烷基二硫代甲酸钼(MoDTC)中的活性元素与摩擦副材料表面发生了摩擦化学反应。温度和摩擦机械作用能显著促进：MoDTC与摩擦表面的摩擦化学作用。MoDTC的存在促进了全配方发动机油SJ／5W-30中的多功能添加剂ZDTP的分解。采用添加MoDTC的油样润滑时，在铸铁磨损表面上能形成Mo的化合物(MoO3，MoS2)以及硫化物(FeS)；纯基础油样SJ/5W-30润滑时铸铁磨损表面上只有硫化物形成，而且所形成的硫化物除FeS之外，还有较多的硫酸盐(FeSO4)。MoDTC与ZDTP甲复配时边界反应膜的形成可采用Pearson的硬软酸碱(HSAB)原理来阐释。     

金属陶瓷添加剂对船舶主机汽缸套-活塞环摩擦学行为的影响

将普通CD40润滑油作为基础润滑油，在3种不同的载荷作用下，对含有金属陶瓷添加剂润滑油对汽缸套-活塞环摩擦磨损特性的影响进行了模拟试验研究，并与实际使用的普通CD40润滑油的试验结果进行了比较。研究结果表明，汽缸套-活塞环摩擦副在这种添加剂作用下，其磨损失重及摩擦因数都大幅度降低。摩擦副表面扫描电镜分析结果也表明，这种添加剂使摩擦表面更光滑，其本身具有表面自修复作用。     

On the influence of surface finish of SSiC on the results of tribological laboratory tests in the case of water lubricated oscillating sliding

The development of materials for tribological applications requires characterisation of their friction and wear behaviour. This characterisation is often based on tribological model testing, working with simple shaped specimens, running under well-defined conditions. Discrepancies in test results may arise from the fact that non-standard tests with different sets of operational parameters are used. An essential starting point for the development of tribological standards is knowledge of the main parameters that influence the tribological properties. One aspect that is not often adequately taken into account is the surface finish of the test specimens. Results are presented of friction and wear tests with self-mated SSiC couples (ball on disc), running in water in an oscillating sliding mode. The surfaces of the disc were ground, lapped, or polished, respectively, running against a polished ball. For certain test conditions, the influence of the surface finish on wear is found to be negligible, while for other conditions, the wear rate can differ by one order of magnitude or even more. The consequences for the standardisation of wear tests of ceramic materials are discussed.     

Effect of additives on a surface textured piston ring–cylinder liner system

ABSTRACT

Laser texturing of the surface is a known approach to improve the tribological performance of mechanical systems. Many studies focused on optimising surface texture parameters for the piston-ring cylinder liner (PRCL) system. However, little attention is given to explore the effect of the textured surface on additive film formation. In the present work, the effect of a laser textured surface on the formation of additives tribochemical films and its impact on the tribological performance of PRCL system is studied. Commercially available steel piston ring and grey cast iron cylinder liner are used as samples to carry out the experiments using linear reciprocating tribometer. Experiments are carried out at 75?N load, 0.1?Hz frequency and 80°C temperature, using polyalphaolefin as base oil mixed with different additives. It is found that dimples are interfering in the formation of tribo-chemical films. However, the hydrodynamic effect of dimples is contributing to the improvement of lubrication performance even in the presence of additives.     

环境与工况对柴油机缸套-活塞环磨损的影响

为研究柴油机实车使用状况下缸套-活塞环磨损规律,建立某12150型多缸柴油机面向使用工况的缸套-活塞环磨损仿真计算方法并进行验证,研究环境与工况参数对缸套磨损的影响规律。结果表明:大气温度升高,缸套磨损深度呈现先减小后增大的趋势,气温-5℃时磨损最小,与-35℃相比下降了5.89%,与40℃相比下降了9.15%;大气压力降低,缸套磨损深度先减小后增大,气压80 kPa时最小,与100 kPa相比下降了6.45%,气压50 kPa时磨损最大,与100 kPa相比升高了8.48%;缸套磨损深度随柴油机转速升高而呈现出增加的趋势,在1 600 r/min时出现极小值点,转速为2 000 r/min相比1 200 r/min磨损深度增加了46.76%;柴油机负荷增加引起缸套磨损深度不断增大,100%负荷时较20%负荷的磨损深度升高了133.96%。