干摩擦条件下WC-Ni/SiC摩擦副的摩擦磨损性能研究

在MMU-10屏显式材料端面摩擦磨损试验机上采用环-环接触摩擦方式,研究了WC-Ni硬质合金与SiC陶瓷材料异配对摩擦副在干摩擦条件下的摩擦磨损性能,并与WC-Ni/WC-Ni硬质合金自配对摩擦副的摩擦磨损性能进行对比.利用扫描电子显微镜与能谱仪对摩擦副的磨损表面进行了观察和分析.结果表明:在相同试验条件下,对比WC-Ni/WC-Ni硬质合金自配对摩擦副,WC-Ni/ SiC摩擦副的摩擦因数稍低点;WC-Ni/ SiC摩擦副的磨损机制主要为磨粒磨损,而WC-Ni/WC-Ni摩擦副磨损机制为粘着磨损兼氧化磨损;由于WC-Ni/WC-Ni摩擦副的磨损表面发生氧化反应和焊合效应,配对效果劣于WC-Ni/ SiC摩擦副.     

新型低树脂基摩擦材料的优化设计及性能研究

为获得制动性能良好、低噪声的摩擦材料配方,采用低树脂设计摩擦材料,并通过正交试验法,对摩擦材料配方进行优化设计。利用定速试验机和压缩试验机等测量摩擦材料的摩擦磨损性能和机械性能,研究配方中各组分对摩擦磨损性能的影响,并利用扫描电镜观察摩擦材料磨损后的表面形貌,以研究其磨损机制。结果表明,鳞片石墨对摩擦因数影响最大,焦炭对磨损率影响最大;树脂含量的变化能改变摩擦材料的磨损机制,树脂含量增加使摩擦材料的磨损机制由疲劳磨损和磨粒磨损转变为单一的磨粒磨损,过量的树脂使得磨损形式转变为黏着磨损和磨粒磨损。树脂含量较高会在摩擦表面形成致密碳化层,摩擦界面形成气垫膜,导致热衰退,而低树脂摩擦材料气孔率较高,摩擦表面光洁,摩擦因数平稳。     

经济型汽车干摩擦式离合器的磨损及影响因素

磨损是经济型汽车干摩擦离合器损坏的主要原因.通过分析经济型汽车干摩擦式离合器在滑动摩擦条件下磨损的基本类型及其影响因素,得出磨粒磨损、粘着磨损和疲劳磨损是其磨损的基本类型,摩擦材料、温度和滑动速度是磨损的主要影响因素;通过分析经济型汽车干摩擦离合器磨损过程三个阶段的磨损类型和磨损量,得出缩短磨合磨损阶段、延长稳定磨损阶段和推迟剧烈磨损阶段可以提高离合器的使用寿命;通过摩擦学性能试验和耐磨损性试验,得出提高离合器摩擦副的材料性能、降低离合器摩擦副的表面粗糙度和改善离合器工作条件(温度、滑动速度和工作载荷)等措施,有助于增强干摩擦式离合器的摩擦性能和耐磨性,从而降低经济型汽车干摩擦式离合器的磨损.     

高速干滑动条件下钢/铜摩擦副摩擦磨损表面摩擦热规律研究

利用MMS-1G高温高速销-盘摩擦磨损试验机,以钢/铜摩擦副为研究对象,进行摩擦磨损试验,使用热电偶对摩擦表层进行测温,应用JSM-5610LV型扫描电子显微镜对摩擦表面进行观察,研究在高速干摩擦条件下摩擦热的影响因素及对表面磨损机制的影响。结果表明:摩擦表面的温度随着速度、载荷的增加而增加;在摩擦初期摩擦温度显著增加,摩擦因数快速下降,当达到某一数值后形成一个动态的平衡;随着摩擦温度的升高,磨损机制发生转变,由粘着磨损转变为磨粒磨损和粘着磨损共同作用。     

多绳摩擦提升机树脂基摩擦衬垫的摩擦学行为

采用CFT往复摩擦磨损试验机研究多绳摩擦提升机树脂基摩擦衬垫在干摩擦条件及不同载荷和滑动速度下摩擦因数的变化规律,采用扫描电镜(SEM)对摩擦衬垫试样的磨损形貌进行观察分析。试验结果表明：不同树脂基摩擦衬垫摩擦因数变化规律具有一致性,即摩擦因数随载荷与滑动速度的增加而减小;由于摩擦衬垫的成分不同,其摩擦因数的主要影响因素不同;磨损形式也由于材料的不同出现黏着磨损、疲劳磨损以及热磨损;载荷对摩擦衬垫磨损的影响比滑动速度更显著。     

微型汽车离合器摩擦材料磨损机制的研究

根据定速式摩擦试验机GB/5763-98国家试验标准,设计了适合研究微型汽车摩擦材料摩擦性能的小样试验;对试验数据进行分析,通过X射线衍射分析、扫描电子显微镜(SEM)分析等手段,对材料的磨损量的变化情况及摩擦面工作层的形成进行分析。结果表明:微型汽车离合器的滑动磨损行为分为轻微磨损和严重磨损,轻微磨损摩擦表面比较粗糙,而严重磨损摩擦表面相对光滑或摩擦噪声明显;轻微磨损以氧化磨损、磨粒磨损为主,伴随着黏着磨损,严重磨损以由严重塑性变形引起的磨损和黏着磨损、磨粒磨损为主。     

M35与GCr15干摩擦磨损性能的研究

在HT-1000型高温摩擦磨损试验机上,对M35高速钢进行干滑动摩擦磨损试验,利用SEM(扫描电镜)观察并分析摩擦面磨损形貌及磨损机理。结果表明,M35高速钢在与GCr15滚动轴承合金钢配副干摩擦条件下,随着速度的增加,摩擦因数先降低后升高,然后再降低。当摩擦热累积达到一定值后,摩擦表面产生严重塑性变形和化学变化,摩擦副表面产生氧化磨损、粘着磨损、磨粒磨损和犁沟磨损,形成转移润滑膜,此时摩擦因数较低,磨损率也相对较低。     

高速条件下PTFE编织复合材料的摩擦磨损性能

将PTFE编织复合材料与9Cr18Mo钢组成摩擦副,在高速压摆摩擦磨损试验机上进行干摩擦磨损试验,研究了循环次数和摩擦温度对摩擦因数的影响,用扫描电镜观察了不同阶段摩擦表面及磨屑的形貌,并分析了PTFE编织复合材料的磨损机理。结果表明:PTFE复合材料的摩擦因数随着循环次数的增加先迅速降低,后在一定范围内达到动态平衡,随着摩擦的继续进行,摩擦因数急剧上升,PTFE复合材料发生磨损失效;摩擦温度是影响PTFE复合材料摩擦磨损机制一个重要因素,摩擦温度的急剧升高将加剧PTFE复合材料的磨损;随着磨损的加剧,磨屑也表现为相应的恶化趋势;磨损机理以疲劳磨损为主。     

多纤维增强汽车制动器摩擦材料的摩擦磨损特性研究

制备一种多纤维增强汽车制动器摩擦材料。为了解多纤维增强摩擦材料各组分在制动摩擦过程中所起的作用,采用XD-MS定速式摩擦试验机测定所制备的摩擦材料的摩擦磨损性能,通过扫描电镜观测在不同温度下磨损后的表面形貌。结果表明:摩擦材料的摩擦因数比较稳定且在高温时摩擦因数没有显著下降,磨损率也在规定范围内;摩擦材料在低温下主要是磨粒磨损,高温下树脂分解产生热磨损,同时伴随着磨粒磨损和疲劳磨损。     

碳纤维增强杂萘联苯聚醚砜酮复合材料的摩擦学性能

利用MRH-03型环-块摩擦磨损试验机研究不同碳纤维含量的聚醚砜酮(PPESK)基复合材料的摩擦磨损性能,讨论载荷、速度及润滑介质对质量分数10%碳纤维增强复合材料摩擦磨损性能的影响,并用SEM观察材料的断面形貌和磨损表面形貌。结果表明:适量碳纤维的加入可以明显提高材料的摩擦磨损性能,并使得复合材料干摩擦条件下的磨损机制由严重的磨粒磨损和黏着磨损转变为黏着磨损和轻微的磨粒磨损。以质量分数10%碳纤维增强的复合材料为例,随着载荷的增加复合材料在干摩擦条件下的摩擦因数降低,而磨损率先降低后增加,在高滑动速度下复合材料的摩擦因数降低而磨损率增加;而海水润滑介质的加入大大降低了材料的摩擦因数和磨损率,并使得复合材料的磨损机制由干摩擦条件下的黏着磨损和轻微的磨粒磨损转变为轻微的磨粒磨损。     

强力切削复合添加剂的研究

本研究以硫、磷、氯极压添加剂为基础。在四球试验机和钻削试验台上,通过正市场调节设计试验找出最佳配比,然后在此基础上,研究了其它化合物对极压添加剂的增效作用,研制成功ＳＣ强力切削复合添加剂,该剂按２０ｗｔ％比例加入到矿油中,可使机油的最大无卡咬负荷提高１００％以上,烧结负荷提高２００％以上,攻丝扭矩下降的４０％。     

复合式增材制造技术研究现状及发展

形性问题制约金属增材制造技术的发展与应用,复合式增材制造在解决制件形性问题方面效果显著。高度概括了复合式增材制造技术分类方式与主体类别;简要总结了增减材复合制造在制件成形精度和表面质量控制方面的研究进展和技术发展状况;重点评述了增等材复合制造技术类别、成形原理、制造特征和关键问题,以及在制件显微组织、应力状态、宏观性能调控方面的研究现状和主体结论;系统介绍了超声、电磁、激光三类特种辅助能场对增材熔池流动、结晶、固态相变的作用机制,以及特种能场作用下,增材层显微组织状态、力学性能、成形精度的演化规律;展望了复合式增材制造技术未来的发展趋势。     

Evaluation of surface fatigue performance of gear oils

The effect of additive chemistry on the surface fatigue of gears was investigated using an FZG gear tester and fluids based on an API GL-5 grade gear oil. Surface fatigue lives were determined as a function of load and additive chemistry. At 1.52 GPa, the removal of the primary extreme pressure (EP) additive from the fully formulated gear oil decreased the fatigue life of gears slightly (4%). However, the removal of the primary antiwear (AW) additive decreased the fatigue life of gears significantly (83%). At 1.86 GPa, the removal of the EP additive from the fully formulated gear oil decreased the gear fatigue life by 27%. However, the removal of the primary AW additive decreased the fatigue life of gears significantly (75%). Micro-pitting was the dominant surface morphology in the dedendum of the gears tested with two oils at load stage eleven: one using the complete additive package, and a second where the EP additive had been removed. However, spalling was the primary failure mode of gears tested without an AW additive, independent of whether an EP agent was present. Surface analysis of the pinion gears showed the formation of a mixed phosphate/phosphite—oxide layer on the surface of gears tested with fluids containing an AW additive. Formation of this layer seems to be the key to a long fatigue life.     

Lubricant and additive effects on spur gear fatigue life

Spur gear endurance tests were conducted with six lubricants using a single batch of consumable-electrode vacuum melted (CVM) AISI 9310 spur gears. The sixth lubricant was divided further into four batches, each of which had a different additive content. Lubricants tested with a phosphorus-type load carrying additive showed a statistically significant improvement in life over lubricants without this type of additive. The presence of sulphur-type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears. No statistical difference in life was produced with those lubricants of different base stocks but with similar viscosity, pressure-viscosity coefficients and antiwear additives. Gears tested with a 0.1 wt % sulphur and 0.1 wt % phosphorus EP additives in the lubricant had reactive films that were 200 to 400 Å (0.8 to 1.6 μin) thick.     

Some Effects of Additives on Rolling Contact Fatigue

To study the influence of lubricant physical and chemical properties on rolling contact fatigue, a variety of base stocks and additives were evaluated with a 4-ball type fatigue machine. The effect of viscosity was found to depend on the means by which a given viscosity was achieved. Although some commonly used EP and antiwear additives had a pronounced effect on fatigue life, the direction and magnitude of the additive effect depended on the particular additive and its concentration in the blend. In addition, it was observed that the additive effect depended on the choice of base oil and ball steel. These results indicate that the chemical properties as well as the physical properties of the lubricant, can be important in rolling contact fatigue.     

The application of photoelectron spectroscopy to the study of e. p. films on lubricated surfaces

Photoelectron spectroscopy (ESCA) has been used to examine films formed on the surfaces of steel specimens by oil solutions of e.p. additives in immersion and rubbing tests. The additives used were elemental sulphur, dibenzyl disulphide, a commercial zinc dialkyldithiophosphate and pure zinc di-n-butyldithiophosphate. In the case of the two sulphur additives immersion specimens had films containing sulphate and free sulphur, whereas rubbed surfaces had patchy coatings of sulphide with lesser amounts of sulphate. The thiophosphate additives gave broadly similar films in rubbing and immersion tests. These contained the zinc, phosphorus and part of the sulphur in the original additive in films, possibly polymeric, of somewhat variable composition. Argon ion etching was used to explore the composition of a film from a thiophosphate additive. It showed that there were no large compositional variations through the thickness of the film and that it was of a discontinuous patchy nature.     

油溶性Cu纳米微粒添加剂对几种商品润滑油摩擦性能的影响

采用液相还原法制备了油溶性铜纳米微粒 ,用四球摩擦磨损试验机考察了其在SJ 5W /3 0汽油机油、CD 15W/4 0柴油机油及GL 4中负荷齿轮油中的摩擦学性能。结果表明 :油溶性纳米铜添加剂可以在一定程度上改善SJ 5W/3 0汽油机油和CD 15W/4 0柴油机油的抗磨作用 ;在较高载荷和浓度下则可以显著改善CD 15W /4 0柴油机油的抗磨作用 ;但其对基础油减摩作用的影响较小。油溶性纳米铜添加剂可望作为减摩抗磨剂直接用于SJ及CD成品油 ,但不宜用于GL 4齿轮油     

Frictional behaviour of imidazolium sulfate ionic liquid additives under mixed slide to roll conditions: part 2 — influence of concentration and chemical composition of ionic liquid additive

Current work presents the investigation of frictional behaviour of ionic liquid lubricant mixtures under mixed slide to roll ratio. On the contrary to the previous study, which focuses on determination of the most suitable ionic liquid additive for identical ionic liquid weight concentration in lubricant mixture, this work had two scopes. The first one was to determine the optimal chemical composition of ionic liquid additive by investigating the lubricant mixtures with identical molar ratio, and the second one, to optimise additive concentration for certain ionic liquid structure. The changes were observed by two means. Namely, in frictional behaviour, ionic liquid concentration plays significant role. On the contrary, for the mixtures with identical molar concentration, the chemical structures with longer alkyl substituent do not always exhibit improvement. Experiments also revealed correlation between ionic liquid structures, concentration and wear. Atomic force microscopy (AFM) analysis of worn surfaces confirmed the above statements. Copyright © 2015 John Wiley & Sons, Ltd.     

FAP− Anion Ionic Liquids Used in the Lubrication of a Steel–Steel Contact

This study compares the tribological behavior of two ionic liquids ([BMP][FAP] and [(NEMM)MOE][FAP]) used as oil additive for the lubrication of a steel–steel contact. Friction and wear experiments were performed using a HFRR test machine. Friction coefficient and electrical contact resistance were measured during the tests, and the wear surface was analyzed by confocal microscopy and XPS. The tribological results showed that both ionic liquids used as additive decrease friction and wear but the [BMP][FAP] had a better performance than the [(NEMM)MOE][FAP] due to its higher reactivity with the steel.     

Study of silane-based antiwear additives: Wear and chemistry

The chemistry and wear performance of a silane-containing additive in combination with conventional commercial engine oil additives such as zinc dialkyldithiophosphate (ZDDP), calcium-type detergent (Ca detergent), and B- and N-containing dispersant were investigated. The tribological behavior of the low-sulfur base stock 100 N blended with the above additives was investigated using a pin-on-disc Plint friction and wear tester at 100 °C. The wear scar width (WSW) of the upper steel pins was determined using an optical microscope. X-ray absorption near-edge structure (XANES) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to analyze the chemistry and thickness of the thin tribofilm formed on the disc. The morphologies of the wear scars on the lower steel discs were observed using an atomic force microscope (AFM). It was found when the silane additive is mixed with Ca detergent and B- and N-containing dispersant, the antiwear performance of the blend was greatly improved, while the friction coefficient remained almost unchanged. Indeed, the wear performance was comparable to or better than ZDDP on its own, and much better than a commercial oil blend. The silane additive is converted to hydrous SiO₂ by the water in the oil, and this SiO₂ then interacted chemically with the surface and Ca in the detergent under sliding to form a relatively thick tribofilm containing mainly a Ca silicate species. The incorporation of Si and B had little effect on the tribochemistry of ZDDP in the oil blends. When ZDDP and B- and N-containing dispersants were mixed with the silane additive, polyphosphate-type tribofilms, similar to that of ZDDP alone, were formed. However, addition of ZDDP had adverse effects on the wear performance of the silane-based blend.