Antiwear Tribofilm Formation on Steel Surfaces Lubricated With Gear Oil Containing Borate,Phosphorus, and Sulfur Additives

The formation of antiwear tribofilms plays a critical role in the longevity of automotive gears. The focus of this experimental study was on the lubrication efficacy of gear oils with different contents of borate-, phosphorus-, and sulfur-containing additives leading to the formation of protective tribofilms. Experiments were performed with AISI 52100 steel balls sliding against AISI 52100 steel disks in baths of different oils at ambient (～32 °C) and elevated (～100 °C) temperatures under load and speed conditions favoring sliding in the boundary lubrication regime. Friction coefficient responses accompanied by electrical contact voltage measurements provided real-time information about the formation and durability of the antiwear tribofilms. The wear resistance of the tribochemical films was quantified by wear rate data obtained from surface profilometry measurements of wear tracks on the disk specimens and sliding tests performed at ambient temperatures after the formation of the tribofilms during elevated-temperature sliding. Results indicate a strong dependence of tribofilm formation on temperature and type of additives. The slightly lower friction and higher wear resistance obtained at elevated temperatures with blended oils is attributed to the increased chemical reactivity of additives containing borate, phosphorus, and sulfur, leading to the formation of durable tribofilms. Relatively higher wear resistance and faster tribofilm formation were obtained with the borate-enriched gear oil formulations.     

基体偏压对磁控溅射制备CrAlN薄膜摩擦学性能的影响

通过分析不同基体偏压下磁控溅射(PVD)CrAlN薄膜的结构特征、硬度规律及磨痕形貌,研究基体偏压对CrAlN薄膜的结构、硬度及摩擦磨损性能的影响。借助扫描电子显微镜(SEM)和原子力显微镜(AFM)观察CrAlN薄膜的表面形貌及三维形貌。采用纳米压痕仪对CrAlN薄膜的硬度进行测定。利用球盘式摩擦磨损试验机测定CrAlN薄膜的摩擦系数,并观察薄膜的磨痕形貌,分析薄膜的磨损机理。结果表明:当基体偏压低于150V时,薄膜表面颗粒的平均尺寸随偏压增大而逐渐减小;当基体偏压超过150V时,薄膜表面出现有明显的缺陷。随着基体偏压的增大,薄膜的硬度呈先升高后降低的趋势,并在基体偏压约为150V时达到最大值为27.5GPa;薄膜的摩擦系数呈先减小后增大的趋势,并在基体偏压约为150V时达到最小值0.25;磨痕呈不同程度的犁沟状,在基体偏压为150V时磨痕形貌平整且犁沟最小。当基体偏压为150V时,CrAlN薄膜的表面缺陷最小、硬度最大、摩擦系数低和综合性能最好,薄膜的磨损机理为磨粒磨损。     

干摩擦状态下动载荷特性对磨损的影响

在自行研制的环一块磨损试验装置上研究了干摩擦状态下矩形波载荷特性对磨损的影响,结果表明。1)矩形波载荷和静载荷作用下试件的磨损过程一样,存在跑合期和稳定磨损期;2)矩形波载荷的占空比愈小,跑合期磨损量愈少,跑合期愈长。     

SiCp/AI有机摩擦材料摩擦磨损特性研究

对20%Vol SiCp/AI复合材料与有机摩擦材料组成的摩擦副的摩擦磨损特性进行了试验研究.试验表明:该摩擦副在不同的速度情况下都具有平稳的摩擦系数.摩擦系数在一定速度范围内随速度增加而减小,而在超过一定速度后随速度增加而增大.对摩擦系数随速度变化的机理进行了讨论.     

含超细颗粒固液二相流对PSZ陶瓷与钢摩擦磨损特性的影响

在往复式摩擦磨损试验机上研究了含超细颗粒固液二相流对部分稳定二氧化锆（ＰＳＺ）陶瓷与ＧＣｒ１５钢滑劝副的摩擦磨损性能的影响。选择９０＾＃机械油和ＱＣ３０汽机油为基础油,分别加入五种超细固体颗粒,配制出不同浓度的２０种油样,分别在１６０１７０和１００℃温度下进行试验。结果表明：超细固体颗粒添加剂的用量、试验温度和基础油都影响陶与钢滑动副的摩擦磨损性能。对超细颗粒添加剂的润滑机理进行了初步探讨。     

Monitoring of Wear Characteristics of TiN and TiAlN Coatings at Long Sliding Distances

TiN and TiAlN thin hard coatings have been widely applied on machine components and cutting tools to increase their wear resistance. These coatings have different wear behaviors, and determination of their wear characteristics in high-temperature and high-speed applications has great importance in the selection of suitable coating material to application. In this article, the wear behavior of single-layer TiN and TiAlN coatings was investigated at higher sliding speed and higher sliding distances than those in the literature. The coatings were deposited on AISI D2 cold-worked tool steel substrates using a magnetron sputtering system. The wear tests were performed at a sliding speed of 45 cm/s using a ball-on-disc method, and the wear area was investigated at seven different sliding distances (36–1,416 m). An Al₂O₃ ball was used as the counterpart material. The wear evolution was monitored using a confocal optical microscope and surface profilometer after each sliding test. The coefficient of friction and coefficient of wear were recorded with increasing sliding distance. It was found that the wear rate of the TiAlN coating decreases with sliding distance and it is much lower than that of TiN coating at longer sliding distance. This is due to the Al₂O₃ film formation at high temperature in the contact zone. Both coatings give similar coefficient of friction data during sliding with a slight increase in that of the TiAlN coating at high sliding distances due to the increasing alumina formation. When considering all results, the TiAlN coating is more suitable for hard machining applications.     

Friction and Wear Behavior of Steels under Different Reciprocating Sliding Conditions

The friction and wear behavior of ISO 100Cr6 steel ball sliding against conventionally hardened carbon and low-alloy steels was studied. The effect of hardness, hardening capacity, normal load, and sliding speed on the coefficient of friction and friction energy was investigated. Friction tests were carried out, without lubrication and under ambient conditions, on a reciprocating friction tester in which a ball-on-flat contact configuration was adopted. The results showed that there is a relative tendency for the friction properties to decrease with increased hardening capacity and decreased hardness. The results showed that increasing normal load decreases the coefficient of friction for the two steel nuances. However, increasing sliding speed increases the coefficient of friction of low-alloy steel and decreases the coefficient of friction of carbon steel. The oxidation of wear debris influences the wear mechanisms and friction behavior.     

青铜-石墨复合粉末热喷涂层的干滑动摩擦磨损性能

研究了石墨含量和载荷等对青铜-石墨复合粉末热喷涂自润滑涂层干滑动摩擦磨损性能的影响。结果表明：青铜-石墨热喷涂层有很好的自润滑性能，石墨含量为6％的涂层抗磨损性能最优。     

烷基结构对 MoDDPs摩擦磨损性能的影响

制备了不同碳原子数的伯，仲烷基MoDDPs，并研究了其油溶性，测定了其加入到100SN基础油中的抗磨性，减摩性和极压性，比较了烷基碳链的长短及伯，仲烷基不同结构对MoDDPs摩擦磨损性能的影响。结果表明仲烷基MoDDPs的摩擦磨损性能优于伯烷基MoDDPs。     

润滑油添加剂对聚合物材料摩擦磨损性能的影响研究

利用MM－200型磨损试验机考察了ZDDP对聚合物材料（PTFE、PI及MCPA）－GCr15轴承钢摩擦副摩擦磨损性能的影响。研究发现，液体石蜡及含ZDDP的液体石蜡润滑均可大幅度改善聚合物材料的摩擦磨损性能，且使其摩擦系数比干摩擦时降低一个数量级，摩擦副表面的ZDDP吸附膜均在不同程度上提高聚合物材料的耐磨性，但其对聚合物材料的摩擦性能影响不大。     

A High-Resolution TEM/EELS Study of the Effect of Doping Elements on the Sliding Mechanisms of Sputtered WS2 Coatings

It has been shown many times that cosputtering low-friction coatings of molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) with other elements can improve the structural, mechanical, and tribological properties. To achieve the lowest friction, MoS₂ or WS₂ should be doped with element(s) improving the hardness and density of the coatings. On the other hand, such elements, or their compounds, should not be present in the outermost molecular layers at the sliding interface. This article suggests that there are important differences between how MoS₂ and WS₂ coatings respond to or react with doping elements, despite the almost identical structure and behavior of the undoped materials. Two systems have been investigated by high-resolution transmission electron microscopy (HRTEM) and scanning TEM (STEM) electron energy loss spectroscopy (EELS), W-S-C-Cr and W-S-C-Ti, and showed significant amounts of oxides, which typically formed a layer just underneath the crystalline WS₂ top layer. Further, carbon was almost completely absent in the tribofilms, despite the fact that the as-deposited coatings contained as much as 40–50 at% C. An interesting observation here is that WS₂ basal planes surround or embed Fe wear particles, suggesting a relatively strong adhesion or a Fe-S chemical bonding between iron/steel and WS₂. The result of this is that the wear particles become pacified and remain in the contact as low-friction material.     

Acoustic Emission and Its Relationship with Friction and Wear for Sliding Contact

Further investigation of the relationships between friction and wear properties and the characteristics of acoustic emission was conducted in the case of dry and grease-lubricated sliding contact using a ball-on-cylinder testing apparatus. The effect of contamination simulated by the inclusion of glass bead particles was also explored. Experiments were performed at sliding speeds ranging from 0.09 m/s to 1.47 m/s, while maintaining a fixed load and duration. As a first observation and contrary to what could be expected, the higher speed did not contribute to the decrease in friction interpreted by a worsening of the starved regime that had a consequence of increasing wear. However, the results revealed a good correlation between the friction coefficient and acoustic emission (AE) rms voltage for dry sliding. Such a relationship may allow the prediction of a reasonable friction coefficient μ from an AE signal. It was also determined that the friction work correlated well with the corresponding integrated AE voltage over time, intRMS. The detection of the sliding speed threshold beyond which accelerated wear would occur was possible from the intRMS variation. Proportionality between the theoretically determined grease film thickness and the intRMS was observed.     

硅油润滑对莫来石基陶瓷摩擦磨损性能的影响研究

莫来石基陶瓷具有一系列优异的性能,其在摩擦学领域中的应用越来越广泛。本文研究了硅油润滑对该类陶瓷摩擦磨损性能的影响规律。研究结果表明,硅油可明显地降低莫来石基陶瓷的摩擦系数和磨损率,但却使摩擦系数在稳定阶段的波动幅度增加。硅油润滑条件下,莫来石基陶瓷的磨损机理主要是微观断裂和磨料磨损。     

填料对超高分子量聚乙烯摩擦磨损性能的影响研究

用MPV－200型摩擦磨损试验机和腐蚀磨损试验机,研究了MoS2,PTEF,石墨,玻璃纤维,碳纤维等填料对超高分子量聚乙烯（UHMW－PE）摩擦磨损性能的影响,结果表明：填充MoS2,PTFE,石墨可降低UHMW－PE的摩擦系数;而添加玻璃纤维则增大了UHMW－PE的摩擦系数,添加碳纤维对UHMW－PE的摩擦系数几乎无影响,同时,添加填料可使UHMW－PE的耐磨性显提高,其中石煌减摩抗磨效果最佳,超高分子量聚乙烯基体的和石墨填料的构成的复合材料,同超高分子量乙烯相比,不仅耐磨性大幅度提高,而且磨擦系数大大降低。     

Dry Sliding Friction and Wear Characteristics of Cu-Sn Alloy Containing Molybdenum Disulfide

The wear and sliding friction response of a hybrid copper metal matrix composite reinforced with 10 wt% of tin (Sn) and soft solid lubricant (1, 5, and 7 wt% of MoS₂) fabricated by a powder metallurgy route was investigated. The influence of the percentages of reinforcement, load, sliding speed, and sliding distance on both the wear and friction coefficient were studied. The wear test with an experimental plan of six loads (5–30 N) and five sliding speeds (0.5–2.5 m/s) was conducted on a pin-on-disc machine to record loss in mass due to wear for two total sliding distances of 1,000 and 2,000 m. The results showed that the specific wear rate of the composites increased at room temperature with sliding distance and decreased with load. The wear resistance of the hybrid composite containing 7 wt% MoS₂ was superior to that of the other composites. It was also observed that the specific wear rates of the composites decreased with the addition of MoS₂. The 7 wt% MoS₂ composites exhibited a very low coefficient of friction of 0.35. The hardness of the composite increased as the weight percentage of MoS₂ increased. The wear and friction coefficient were mainly influenced by both the percentage of reinforcement and the load applied. Wear morphology was also studied using scanning electron microscopy and energy-dispersive X-ray analysis.     

PTFE基改性复合材料的摩擦磨损性能及其在铁路机械中的应用

概述了聚四氟乙烯（PTFE）基自润滑改性复合材料的摩擦磨损性能研究新进展。讨论了纤维增强、无机填充、有机共混和离子注入表面改性复合材料的摩擦学性能以及PTFE基改性复合材料在铁路机械中的应用。     

润滑油添加剂对聚合物及其复合材料摩擦磨损性能的影响

利用MHK-500型环-块磨损试验机研究了二烷基二硫代磷酸锌(ZDDP)对几种聚合物及其复合材料-金属摩擦副油润滑摩擦磨损性能的影响。结果表明,液体石蜡中的ZDDP对尼龙66(PA66)及聚酰亚胺(PI)-GCr15轴承钢摩擦副的摩擦系数影响不大,但却使聚四氟乙烯(PTEE)及其复合材料-GCr15轴承钢摩擦副的摩擦系数略有降低。PTEE及其复合材料-GCr15轴承钢摩擦副表面的ZDDP吸附膜具有一定的抗磨作用,它大幅度降低了Pb、PbO及MoS     

Friction and Wear Behaviors of TiN Coatings under Dry and Vacuum Conditions

In this study, pure TiN coatings were applied on AISI 52100 steel surfaces with a magnetron sputterer at different direct current (DC) powers and N₂ flows to develop a wear-resistant coating for sliding tribopairs working in atmospheric and vacuum conditions. Wear and friction characteristics of these coatings were investigated with a tribometer under both vacuum and atmospheric conditions. DC power and N₂ flow affected the coating thickness and structure. TiN coatings showed different wear and friction characteristics under ambient and vacuum conditions due to the oxidation level of the surface.     

Effect of Load and Composition on Friction and Dry Sliding Wear Behavior of Tungsten Carbide Particle-Reinforced Iron Composites

Investigations on the dry sliding wear behavior of tungsten carbide (WC)-reinforced iron matrix composites were carried out at room temperature. Three sets of samples (unreinforced iron, 4 wt% micrometer-size (～5–15 μm) WC-reinforced iron and 4 wt% nanosize (～30 nm) WC-reinforced iron were prepared using a powder metallurgy route to assess their friction and wear behaviors under two different loads. The relative dry sliding wear performances of the micrometer-size and nanosize WC-reinforced composites were compared with unreinforced matrix. An increase in microhardness of the order of 2.5 times was observed in the case of 4 wt% nanosize WC-reinforced iron matrix compared to the unreinforced iron matrix. The wear rate was 1.35 to 1.45 times lower in the case of nanocomposites compared to the unreinforced iron matrix (under different experimental conditions). The values of the coefficient of friction (COF) of composites were found to decrease with increase in load. Nanocomposites showed lower COF, surface roughness, and fractal dimension (D) values than micrometer-size WC-reinforced composites and the unreinforced iron matrix.     

改进微静电马达的摩擦与磨损

在微观结构中,摩擦及磨损严重地影响着部件的力学性能和可能性不同材料的摩擦系数相差很大,多晶硅和多晶硅之间的静摩擦系数约４．９,多晶硅和单晶硅之间的静摩擦系数约０．４８￣０．２８,动摩擦系数约０．３５￣０．２０,材料表面的粗糙度对摩擦系数影响也很大。鉴于此,提出了一种单晶硅台面结构晃动微马达,取代多同机械工艺制作的多晶硅法兰盘。它具有机械强度高、摩擦系数、抗磨损、不塌陷等优点,马达的轴也加工成实心轴