Tribological Performance of Oil-Based Lubricants with Carbon-Fe Nanocapsules Additive

The present study investigates the tribological properties of carbon-Fe nanocapsules (CFNCs) under high contact loads. Block-on-ring wear tests are performed using mineral oil lubricants containing CFNC particles with concentrations ranging from 0.01 to 0.1 wt%. In addition, high-resolution electron transmission microscopy (HR-TEM) and scanning electron microscopy (SEM) analysis were conducted on the test samples. The results show that for a contact load of 650 N, a CFNC concentration of 0.07 wt% and a sliding velocity of 1.65 m/s enhance the surface permeability, fill-up properties, and microbearing lubrication mechanism and promote effective reduction in the wear at the surface contact interface.     

Tribological Study Comparing PAG and POE Lubricants Used in Air-Conditioning Compressors under the Presence of CO2

Polyalkylene glycol (PAG) and polyolester (POE) synthetic lubricants are good candidates for air-conditioning systems that work with alternative refrigerants such as carbon dioxide (CO₂). Both synthetic lubricants are widely used in air-conditioning compressors and have been optimized for use with hydrofluorocarbon (HFC) refrigerants. However, it is still not clear which lubricant is more suitable for use in compressors operating with CO₂ as a refrigerant. This study compares the performance of PAG and POE lubricants of the same viscosity (ISO VG 68) used in air-conditioning compressors. The materials used were Al390-T6 disks and hardened steel SAE 52100 pins. The tests were performed using a high pressure tribometer (pin-on-disk configuration) in the presence of CO₂. The results showed that scuffing and wear resistance of Al390-T6 tested with PAG were superior compared to the samples tested with the POE lubricant. Chemical analysis using X-ray photoelectron spectroscopy showed that PAG tends to promote the formation of carbonate layers on the surface, leading to improvement in the tribological performance of the interface.     

全氟聚醚润滑剂及其摩擦学特性研究

本文综述了全氟聚醚（PFPE）润滑油和脂的物理、化学性质和摩擦学特性，同时还对它们的制备方法和应用情况进行了论述。     

Boundary Lubrication of Steel Surfaces with Borate,Phosphorus, and Sulfur Containing Lubricants at Relatively Low and Elevated Temperatures

Prolonging the life of engineering components through lubricant formulation to achieve better wear resistance and higher oxidation stability is of paramount importance to many mechanical systems, such as automotive gears and bearings. This can be accomplished with formulated lubricants that limit the generation of wear debris causing severe abrasion and protect the contacting surfaces through the formation of wear-resistant tribofilms. In this study, a ball-on-disk tribometer was used to characterize the friction and wear properties of steel surfaces slid in the boundary lubrication regime. An experimental scheme was developed to allow the statistical screening of various lubricant formulations. Sliding experiments were performed in baths of different lubricants at relatively low and elevated temperatures, approximately 32 and 100°C, respectively, under conditions of constant load and sliding speed. Surface profilometry, optical microscopy, and scanning electron microscopy were used to characterize the dominant friction and wear mechanisms. The tribological properties were found to strongly depend on the temperature and the additives (e.g., borate, phosphorus, and sulfur) present in the blended lubricants. The superior high-temperature wear performance of the lubricant with the higher borate content is indicative of the formation of a durable tribofilm that reduces metal-to-metal adhesion, material transfer, and surface plowing by wear debris.     

Additive Mechanism Investigation of Perfluoropolyether Lubricants with a Phosphazene Additive

The tribological characteristics of magnetic thin film media coated with perfluoropolyether (PFPE) lubricants (ZDOL and AM300J) and a phosphazene additive (X-IP) were investigated in this study. The drag test results show that under ambient and hot/wet conditions the media coated with AM300J lubricant have higher retention on the test track than those coated with ZDOL 2000 PFPE lubricant. The phosphazene additive X-IP was observed to strongly anchored to the surface and was not as easily removed as PFPE lubricants alone. The retention characteristics of X-IP are independent of either AM or ZDOL. Secondary Ion Mass Spectroscopy (SIMS) depth profile data and Angle-Resolved X-Ray Photo-electron Spectroscopy (XPS) reveal that X-IP molecules were distributed near the disk surface in the X-IP and PFPE lubricants mixed layer, indicating a strong bonding/adhesion of X-IP to the disk surface. Together with the drag testing data, the authors conclude that the preferential distribution of X-IP close to the disk surface in the mixed layer helps to improve lubricant retention performance at the head-disk interface.     

Comparative Study on Wear Behaviors of Metal-Impregnated Carbon Material and C/C Composite Under Electrical Sliding

In this article, the wear behavior of metal-impregnated carbon materials (MIC) and carbon–carbon composites(C-C) was investigated using a self-made current-carrying wear tester producing an electrical current of 40–160 A and a contact speed of 10–50 m/s. The worn surfaces were observed by means of scanning electron microscopy (SEM), and a new parameter for current-carrying stability that describes the stability of the current as a function of wear was proposed. The results indicate that the wear rate of both materials tested increased with either an increase in electrical current or contact sliding speed. Compared to the metal-impregnated carbon material, the C-C composite material not only displayed superior wear resistance but superior current-carrying stability as well. With increasing electrical current, the current-carrying stability of the two materials changed within a narrow range at a speed of 20 m/s and decreased at a speed of 50 m/s. Wear failure was mainly due to electrical erosion occurring at high speed and high current.     

几种添加剂在一些环境友好润滑剂基础油中的抗磨减摩探讨

本文对一些环境友好润滑剂基础油（酯型合成油和天然植物油脂）的摩擦特性及润滑化学主要性能进行试验研究，对一些油性和极压添加剂：氯化石蜡、硫化异丁稀、ZDTP、TAW（上海大学产无灰、氮磷型）的抗磨、减摩效果进行比较，并和纳米型（CF）x进行了比较。     

Experimental Study on the Effect of Microstructure on Dry Sliding Wear Behavior of Titanium Alloy Using Taguchi Experimental Design

The present article depicts the influence of independent control factors such as microstructural variation, normal load, sliding velocity, and test duration on the dry sliding wear behavior of titanium alloy at room temperature using a statistical approach. Different heat treatments were carried out in a controlled manner to produce various microstructural features (i.e., lamellar, bimodal, and equiaxed) in this alloy. A lamellar microstructure is found to be harder than bimodal microstructure followed by an equiaxed microstructure in this alloy. Dry sliding wear tests were carried out using a multiple tribotester following a well-planned experimental schedule based on Taguchi's orthogonal arrays. The dry sliding wear behavior of this alloy consisting of various microstructural features is related to their hardness values. The results indicated that a lamellar microstructure has the lowest sliding wear resistance followed by bimodal and equiaxed microstructures. Using signal-to-noise ratios and analysis of variance (ANOVA), an optimal combination of control factors that minimize the dry sliding wear in this alloy were determined. Among all four control factors, normal load is the most significant control factor influencing the dry sliding wear behavior of the investigated titanium alloy, followed by microstructural variation, sliding velocity, and test duration. Normal load has a greater static influence of 39.53%, microstructural variation has an influence of 31.55%, sliding velocity has an influence of 21.6%, and test duration has an influence of 5.7% on the dry sliding wear of this alloy. Two wear mechanisms were identified: oxidative wear occurs at the lowest sliding velocity and delamination wear occurs at the highest sliding velocity. Optical microscopy, scanning electron microscopy, and Rockwell hardness measurements were used to characterize the microstructures in order to correlate the results obtained.     

Prediction of Surface Topography at the End of Sliding Running-In Wear Based on Areal Surface Parameters

Running in is a complex process, and it significantly influences the performance and service life of wear components as the initial phase of the entire wear process. Surface topography is an important feature of wear components. Therefore, it is reasonable to investigate the running-in process with the help of surface topography for improvement. Because the surface roughness after running in is independent of the nature of initial roughness, it is difficult to predict the surface topography after running in based on unworn surface topography. Aiming to build a connection of surface topographies before and after the running-in process, a black-box model predicting surface topography after the running-in process was established based on least-squares support vector machine (LS-SVM), and the areal surface evaluation parameters were adopted as model variables. To increase the adaptability of the predictive model, the main factors of the work condition were also taken into consideration. The prediction effect and sensitivity of the model were tested and analyzed. The analysis indicates that the hybrid property of surface topographies before and after running in is closely related. Moreover, the surface topography after running in is influenced more by the initial surface topography than by the work condition.     

润滑剂综合磨损值ZMZ的简化测定方法研究

通过回归分析建立了以最大无卡咬负荷PB和烧结负荷PD为参数的二元数学模型，使GB/T3142方法综合磨损值的测定工作量减少了二分之一，通过对数学模型的检验和再现性试验证明，简化测定方法的精密度完全符合GB/T3142方法的要求，而且重复性和再现性偏差均低于实测结果。     

Effect of Metallic-Coating Properties on the Tribology of Coated and Oil-Lubricated Ceramics

Friction and wear behavior was determined for zirconia ceramics lubricated with solid coatings (Ag, Au, and Nb) deposited by ion-beam-assisted-deposition (IBAD) techniques, and a polyol-ester-based synthetic oil. Although the use of soft Ag and Au coatings as solid lubricants in conjunction with the synthetic oil significantly reduced the fiction and wear under boundary lubrication at temperatures up to 250°C, these films had poor durability. In contrast, the Nb coating was more durable in terms of chemical reactivity and adhesion during the tribo-tests than were the Ag or Au films. However, the friction and wear behavior of the Nb-coated zirconia was poorer than that of the ceramics coated with Ag or Au.     

The Effect of Shear-Thinning on Film Thickness for Space Lubricants

The authors show that the difference between effective pressure-viscosity coefficients, obtained from film thickness, and coefficients obtained from viscometers for a PFPE space lubricant is substantially the result of shear thinning in the inlet zone of concentrated contact. Flow curves for the PFPE and a multialkylated cyclopentane are presented along with film calculations based on the Carreau model.     

Dry Sliding Friction and Wear Mechanism of TiC-TiB2 Particulate Locally Reinforced Mn-Steel Matrix Composite from a Cu-Ti-B4C System via a Self-Propagating High-Temperature Synthesis (SHS) Casting Route

An Mn-steel matrix composite locally reinforced with in situ TiC-TiB₂ ceramic particulates was successfully fabricated via a self-propagating high-temperature synthesis (SHS) casting route in a Cu-Ti-B₄C system with various Cu contents. The effect of the Cu content on wear behavior, wear surface, and wear mechanism of the composite was investigated against an AISI H13 mating disc in similar testing conditions at various applied loads and sliding velocities. Moreover, the phase identification and microstructure of the composite were examined. With the increase in Cu content, the wear resistance of the Mn-steel matrix composite decreases first and then increases. Impressively, the composite with 30 wt% Cu content has the highest wear resistance. The enhanced wear resistance can be attributed to the combination of size of ceramic particulates, number of pores, and strength of the interfacial bonding. The dominant wear mechanisms of the TiC-TiB₂ ceramic particulate–reinforced Mn-steel matrix are ploughing grooves and delamination wear associated with more abrasion and adhesion.     

Study on Static Supporting Capacity and Tribological Performance of Ferrofluids

In this article, Fe ₃ O ₄ -based ferrofluids (MFs) with different saturation magnetization (Ms) were prepared by the co-precipitation technique. The static supporting capacity of the different magnetization MF drops with a permanent magnet was tested using UMT-2 multi-specimen test system. The tribological performance of the carrier liquid and MF were conducted on a ring-on-cylinder tribometer. The results show that MF under a magnet has a higher supporting capacity compared with the carrier liquid and the supporting capacity of MF increases with the increase of Ms. With an external magnetic field applied, significant improvement in antifriction and wear resistance was obtained by using MF with proper Ms as lubricants.     

The Effect of FeS Solid Lubricant on the Tribological Properties of Bearing Steel under Grease Lubrication

In order to improve the tribological properties of 52100 steel under grease lubrication, FeS solid lubricant was used in two ways. Low-temperature ion-sulfurization technology was utilized to prepare solid lubricant iron sulfide (FeS) films on the surface of 52100 steel, and FeS particles were mixed into the lithium grease as additive. The friction and wear properties were examined systematically on a “ball-on-disc” testing machine. The results showed that the tribological properties of bearing steel under grease lubrication can be improved either by using ion-sulfurization technique or by adding FeS microparticles into the grease. The tribological performance of sulfurized surface lubricated by grease is better than that of a plain surface lubricated by grease containing FeS microparticles at lower load and speed. The plain surface lubricated by the grease containing FeS micropaticles possesses better antiwear property under harsher conditions. The mechanism of the experimental results is discussed in detail.     

普通导轨润滑机理探讨

本文在对导轨滑动表面润滑机理进行研究中，首次提出了微观表面动压润滑的概念，在此基础上深入探讨了导轨滑动表面的润滑机理，从而指出导轨滑动表面润滑状态不应是介于边界润滑与干摩擦之间，而应是介于边界润滑与动压润滑之间。     

Ekonol/G/MoS_2/PEEK复合材料的磨损机理研究

用模压方法制备了Ekonol/G/MoS2 /PEEK复合材料 ,通过摩擦磨损实验方法对材料的耐磨性能进行了研究 ,并用SEM对磨损表面进行了观察和分析 ,在此基础上探讨了复合材料的磨损机理。结果表明 :与PEEK相比 ,复合材料具有优良的耐磨性能 ;随着Ekonol含量的增加 ,复合材料的磨损机理发生了由粘着磨损向疲劳磨损的转变     

一种新型高温测氢传感器探头的研究

利用 Ｙｂ３＋掺杂的ＳｒＣｅＯ３在高温时的Ｈ＋导电特性制作了 ＳｒＣｅ０．９５Ｙｂ０．０５Ｏ３－α高 温测氢探头,并在高温条件下利用该探头对氢在４５＃钢中的扩散行为进行了研究 和分析。所得结果与理论模型计算的结果一致。     

机构磨损的模糊可靠性算法研究

首先介绍了磨损的常规失效判据和可靠性分析方法,然后着重于磨损失效判据的模糊性提出了模糊可靠性的计算公式,并用实例阐明了其概念、思路和方法。     

The effects of load and substrate hardness on the development and maintenance of wear-protective layers during sliding at elevated temperatures

Transitions to low wear rates often occur during sliding between contacting metal surfaces, due to the establishment of high-resistance load-bearing layers. Such layers are developed from compaction of wear debris particles, with adhesion between the particles being an important factor in determining whether the layers are maintained, leading to wear protection, or break down, leading to abrasive wear. They are formed more easily and retained more effectively at higher temperatures, due to increased sintering and adhesion between the debris particles and to enhanced oxidation of these particles. This paper presents the results of a study of the reciprocating sliding wear and friction of dissimilar combinations of pin and disc steel specimens (high-speed steel and high-chrome steel pins and carbon steel discs) at temperatures of 500–600°C, with emphasis on the influence of load and substrate hardness on the development and maintenance of such wear-protective particulate layers. Complex relationships occur between the effects of increased load in producing larger debris particles, in decreasing the critical particle size for establishing the layers and in decreasing the separation between the sliding surfaces, and the effects of hardness of the substrates on the sizes and amounts of wear particles and on the topographies of the wear scars. The relationships are complicated further by oxidation and sintering of debris particles, leading to development of oxide or oxide-containing ‘glaze’ surfaces, and subsequent breakdown of the layers during sliding.