Elastomer modified phenolic resin-based composites with reduced scale friction: Influence of calcined petroleum coke on tribological and thermo-mechanical behavior

The present investigation deals with the effect of the concentration of calcined petroleum coke (CPC) on the dry sliding wear characteristics of elastomer modified phenolic resin-based friction composites. Other ingredients common in brake formulations like fiber, filler, and solid lubricant were excluded in the present formulations to understand the exclusive effect of the CPC concentration on the frictional, mechanical, and thermal properties of these composites. The composites were fabricated by hot mixing followed by compression molding, and subsequent post-curing. The coefficient of friction (COF) and the specific wear rate of these composites sliding against a cast-iron disc were measured and analyzed. The change in surface topography of these composites before and after sliding operation was investigated by scanning electron microscopy. An effort was made to correlate the surface morphology of these composites before and after sliding with friction and wear behavior. The investigation reveals that CPC inclusion improved the anti-wear behavior as it formed a uniform transfer layer over the rubbing surfaces. In case of optimum CPC loaded (200 phr) composite, the average COF and thermal conductivity values were found to be 0.15 and 0.61 W/m-K, respectively, as compared to 0.12 and 0.25 W/m-K for the base composite (without any CPC).     

碳纤维增强PEEK复合材料的摩擦学性能研究

用磨损试验机对碳纤维增强聚醚醚酮（PEEK）复合材料进行室温干滑动磨损试验。考察了碳纤维的含量，石墨润滑剂，对靡时间及载荷对材料靡损量及摩擦系数的影响，并用电子显微镜对其磨损表面进行了观察与分析，同时对材料的磨损机理进行了探讨，研究结果表明，随着载荷的升高和对磨时间的延长，材料的摩擦系数逐渐降低并趋于稳定，磨损量呈上升趋势，加入碳纤维可以明显地降低材料的摩擦系数和磨损量，当碳纤维含量为5％－10％时复合材料的摩擦系数和磨损量最低；加入适量固体石墨可进一步降低复合材料的摩擦系数和磨损量。     

Compression‐molded,lubricant‐treated UHMWPE composites

Lubricant‐treated ultra high molecular weight polyethylene (UHMWPE) composites were prepared by compression molding. Composites were made from mixtures containing up to 5.0 wt % of lubricant. Two solid lubricants, molybdenum disulfide (MoS₂), and carbon black (CB), and one liquid lubricant, perfluoropolyether (PFPE), were used in the study. UHMWPE and the lubricants formed 3D networks, where the lubricant was evenly spread over the UHMWPE particles. The amounts of MoS₂ and CB were determined by thermogravimetric analyses, and the amounts of PFPE by ATR‐IR spectroscopy. All the lubricant treated composites showed better friction properties than pure UHMWPE. The addition of PFPE to UHMWPE improved the hydrophobicity of the surface, whereas the addition of solid lubricant had little effect. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1762–1768, 2007     

Influence of solid lubricant reinforcement on wear behavior of Kevlar fabric composites

The friction and wear behavior of Kevlar fabric composites reinforced by PTFE or graphite powders was investigated using a Xuanwu‐III friction and wear tester at dry sliding condition, with the unfilled Kevlar fabric composite as a reference. The worn surfaces were analyzed by means of scanning electron microscope, and X‐ray photoelectron spectroscopy. It was found that PTFE or graphite as fillers could significantly improve the tribological behavior of the Kevlar fabric composites, and the Kevlar fabric composites filled with 20% PTFE exhibited the best antiwear and antifriction ability among all evaluated cases. The transfer films established with two lubricants in sliding wear of composites against metallic counterparts made contributions to reducing friction coefficient and wear rate of Kevlar fabric composites. In particular, FeF₂ generated in the sliding of Kevlar fabric composites filled with PTFE against counterpart pin improved the bonding strength between the transfer film and counterpart surface, which accounted for the lowest friction coefficient and wear rate of the Kevlar fabric composites filled with PTFE measured in the testing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Friction and wear studies of polyetherimide composites under oscillating sliding condition against steel cylinder

Tribological properties of neat polyetherimide (PEI), glass, carbon fiber, and solid lubricants filled PEI composites are presented in this article. The aim of this study was to investigate the friction and wear properties of these composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120°C). The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. Incorporation of carbon fiber in the PEI matrix has increased the wear rate at RT, while at elevated temperature this trend was opposite. Abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS₂, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated. Tribological performance of neat PEI and glass fiber composite was similar with each other at RT. Scanning electron micrographs and optical micrographs of the worn polymer specimens and the steel cylinders was used to study the possible wear mechanisms. The present test results were also compared with data available on the reciprocating wear of PEI and composites in the literature and trends have been reported. POLYM. COMPOS., 38:48–60, 2017. © 2015 Society of Plastics Engineers     

Friction properties of graphene reinforced nitrile rubber composites after thermal oxidation aging: Experiment and molecular dynamics simulation

We established friction models for pure NBR, GNS/NBR, and GO/NBR composites through molecular dynamics (MD) simulation. Our study focused on the impact of GNS and GO on the friction properties of nitrile rubber (NBR) composite materials after undergoing thermal oxygen aging. Based on the simulation results, it can be observed that the GNS/NBR and GO/NBR composites' coefficient of friction (COF) decreases by 20.8% and 24.8%, respectively, at 348 K. Additionally, the abrasion rate is reduced by 17.4% and 25.7%, respectively, for the same composites. Adding GNS and GO can effectively improve the friction performance of the NBR composite system, and compared with GNS, GO shows a better enhancement effect. Pure NBR and GO/NBR composite materials were prepared by mechanical blending method, and the friction properties of GO-enhanced NBR composite materials were studied. The experimental results show that the GO/NBR composite material can maintain a low friction and wear coefficient after thermal and oxygen aging. It shows that adding GO can effectively improve the friction properties of NBR composite systems and slow down the weakening effect of aging on the friction properties of NBR composite materials. This is because the GO surface contains wealthy functional groups such as epoxy groups, which enhances the binding strength between the GO and NBR interface so that the GO/NBR composite material exhibits better friction properties and thermal oxygen aging resistance. In addition, the wear surface was characterized by scanning electron microscopy (SEM), revealing the damage mechanism of friction and wear of NBR composite materials.     

Study on friction behavior of fabric–silicone rubber composites under dry/wet sliding environment

The dry/wet environment's effects on the sliding friction properties of fabric–silicone rubber composites are studied, and the wear resistance of polyester fabric is evaluated. The yarn directions of the fabrics (inner and outer) have significant influence on the coefficient of friction (COF) of fabric–silicone rubber composites during sliding friction due to the difference in fabric texture and yarn modulus. The COF's variation laws of fabric–silicone rubber composites under different vertical loads and sliding rates are observed, respectively. Additionally, the outer fabric is more sensitive to the changes of vertical loads than those of the sliding rates under the wet environment, which can be attributed to the destruction of the fabric original structure by high load, resulting in the fabric fibers' pulling and breaking during the steel ball's sliding. This study provides new ideas for the design of fabric–silicone rubber composites applied in friction conditions and complex environments.     

Preparation and tribological behavior of polytetrafluoroethylene/metal mesh composites with sandwich structure

Polytetrafluoroethylene (PTFE) owns an excellent self-lubricating performance, but its wear rate is very high due to the large-scale spalling of the matrix in the friction. In this paper, A new kind of PTFE composites with sandwich structure was prepared by layer-press technology, whose middle layer is filled with metal mesh. The influence of the mesh structure and mesh density of middle metal layer on tribological properties of composites were researched in detail. The results revealled that the metal mesh located in the composites can efficiently prevent the large-scale spalling of PTFE, which induces the sample of PTFE/500# plain woven dutch metal mesh (PTFE-500#PWD) to have a lower wear rate (9 × 10⁻⁵ mm³/Nm) and COF (0.106) under the fixed experimental condition. The prepared PTFE/metal mesh composites reveal excellent anti-friction and anti-wear performance, which can be used to fabricate a new kind of self-lubricating materials.     

Effect of solid lubricants on tribological behavior of glass fiber reinforced polyamide 6

The tribological properties of glass fiber reinforced polyamide 6 (GF/PA6, 15/85 by weight) and its composites filled with solid lubricants were investigated. The main purposes of this article were to study the hybrid effect of solid lubricants with glass fiber as well as the synergism of combined solid lubricants, the wear mechanisms were studied by SEM. The results showed that graphite impaired the tribological properties of GF/PA6, but the tribology behavior of graphite filled GF/PA6 composite could be significantly improved by polytetrafluroethylene (PTFE) or/and ultrahigh molecular weight polyethylene (UHMWPE), and the GF/PA6 composite filled with 5 wt % graphite, 5 wt % PTFE together with 5 wt % UHMWPE exhibited the lowest friction coefficient and wear rate, which was almost a reduction in friction coefficient by 37% and in wear rate by 34% contrast to GF/PA6. The effect of load was also studied, and the results showed that the friction coefficient was virtually not affected by load, while the wear rate all increased with increasing load. POLYM. COMPOS., 34:1783–1793, 2013. © 2013 Society of Plastics Engineers     

Silicon doped diamond like carbon as substitute for lubrication in spin-extrusion

To protect tools and to fulfil the request of good surface quality of the workpiece, it is normally necessary to use solid lubricants like molybdenum disulfide (MoS₂) or graphite in warm bulk metal forming. Caused by economical and ecological aspects, it is desirable to avoid lubrication and to substitute it by systems like coatings without the necessity to renew the protecting and lubricating film after every forming process.So called low wear friction coatings like Diamond like Carbon (DLC) are candidates for substituting lubricants or combinations of lubricants and hard coatings like TiN. The advantages of DLC are its high hardness, high Young's modulus and low coefficient of friction. Another important aspect is the property of DLC to graphitise the surface at high pressures, so the coating becomes a kind of self-lubricating. In massive forming at low temperatures like cold extrusion, DLC is applied today.The aim of the work is to show the suitability of DLC as a protective low wear friction coating for warm massive forming, especially for a technique called spin-extrusion. The greatest tribological problems of this forming process are a low sliding velocity and high temperatures in the working zone between tool and workpiece, which can reach a maximum temperature of about 800 °C. Normally, the maximum working temperatures of DLC should be lower than 400 °C when working in air atmosphere. So, the DLC was doped with silicon to raise the maximum working temperature of the coating. Also, the time a-C:H:Si is subjected to this temperature is short, and the air content in the working zone is reduced during the process. The behaviour of a-C:H:Si coated tools during spin-extrusion without additional lubrication of the tool is compared with the forming behaviour of uncoated, but lubricated tools.     

Influences of (3-aminopropyl)triethoxysilane on the tribological behaviors of basalt fiber/acrylonitrile-butadiene rubber composites under dry friction and water-lubricated conditions

The weak interaction between the basalt fiber (BF) and acrylonitrile-butadiene rubber (NBR) weakens the BFs' effects on improving the tribological performances of the NBR composites. To solve this problem, (3-aminopropyl)triethoxysilane (APTES) was introduced via mixing into the matrix or grafting on the BF surface, respectively. The characteristics, mechanical, and tribological properties of the composites were evaluated, and the effects of the APTES and its introduction methods on the tribological properties were the main focus. The APTES mixed in the rubber matrix decreased the friction coefficient (COF) of the NBR-based composites under both dry friction and water-lubricated conditions. Especially, the APTES hydrolysis under water-lubricated condition was conducive to the formation of the water film and thus dramatically decreased the COF. The COF of the BF0-A3 and the BF12-A3 were 51% and 30% lower than that of the BF0-A0 and the BF12-A0 under water lubrication, respectively. The APTES grafted on the BF surface increased the wear resistance of the BF/NBR composites attributed to the improvement of the interaction between the BFs and the NBR matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48558.     

Tribological behaviors of hot-pressed Al2O3/TiC ceramic composites with the additions of CaF2 solid lubricants

Al₂O₃/TiC ceramic composites with the additions of CaF₂ solid lubricants were produced by hot pressing. The effect of the solid lubricant on the microstructure and mechanical properties of the ceramic composite has been studied. The friction coefficient and wear rates were measured using the ring-block method, and the tribological behaviors were discussed in relation to its mechanical properties and microstructure. Results showed that additions of CaF₂ solid lubricants to Al₂O₃/TiC matrix led to a decrease in the flexural strength, fracture toughness, and hardness compared to a conventional Al₂O₃/TiC composite. The friction coefficient of Al₂O₃/TiC/CaF₂ ceramic composites when sliding against both cemented carbide and hardened steel decreased with an increase in CaF₂ content up to 15 vol.%. The reason is that the CaF₂ released and smeared on the wear surface, and acted as solid lubricant film between the sliding couple. When the content of CaF₂ solid lubricant is less than 10 vol.%, the wear rate of Al₂O₃/TiC/CaF₂ composites decreases with an increase in CaF₂ content, with further increases in CaF₂ content, the wear rate of Al₂O₃/TiC/CaF₂ composites increases rapidly. This is due to the large degradation of mechanical properties in samples with high CaF₂ contents.     

PTFE/纳米SiC复合材料的摩擦磨损性能研究

利用冷压烧结法制备了不同含量的聚四氟乙烯/纳米碳化硅(PTFE/纳米SiC)复合材料。采用MM-200型摩擦磨损试验机在干摩擦条件下考察了纳米SiC含量及载荷对PTFE/纳米SiC复合材料摩擦磨损性能的影响,借助于扫描电子显微镜观察分析了试样磨损表面形貌,并探讨了其磨损机理。结果表明,纳米SiC能够提高PTFE/纳米SiC复合材料的硬度和耐磨性,当纳米SiC质量分数为7%时,PTFE/纳米SiC复合材料的磨损量最小,摩擦系数也最小;随纳米SiC含量的增加,其摩擦系数有所增大;随着载荷的增大,PTFE/纳米SiC复合材料的磨损量增加。     

Effect of several solid lubricants on the mechanical and tribological properties of phenolic resin‐based composites

The flake graphite, polytetrafluoroethylene, and molybdenum disulfide (MoS₂) filled phenolic resin‐based composites were prepared by hot press molding. The thermal, mechanical, and tribological properties of composites were studied systematically. The morphologies of the worn surfaces and the change of chemical compositions during the sliding process of the composites were analyzed by scanning electron microscopy and X‐ray photoelectron spectroscopy, respectively. It was found that the heat‐resisting performance and the hardness of the composites are less affected by solid lubricants, while the solid lubricants did harm to the flexural strength of the composites. The friction and wear behaviors of composites highly depended on the volume fractions of solid lubricants and the sliding conditions. The wear resistance increases and the coefficient of friction decreases when the filler load increases. In addition, the appropriate content of solid lubricants is beneficial to reducing the sensitivities of the composites to load and sliding speed. POLYM. COMPOS., 36:2203–2211, 2015. © 2014 Society of Plastics Engineers     

聚四氟乙烯/纳米氮化钛复合材料的摩擦磨损性能研究

利用摩擦磨损试验机考察了填料含量及载荷对纳米氮化钛(TiN)填充聚四氟乙烯(PTFE)复合材料摩擦磨损性能的影响,采用扫描电子显微镜观察分析磨损表面形貌,探讨了磨损机理。结果表明,纳米TiN可以提高PTFE的硬度和耐磨性,当纳米TiN质量分数为7%时,PTFE纳米TiN复合材料的磨损量最小;随载荷的增大,PTFE/TiN复合材料的磨损量增加。PTFE纳米TiN复合材料的摩擦因数比纯PTFE小。     

固体润滑剂对丁腈橡胶复合材料性能的影响

将石墨、石墨烯以及两种不同尺寸的二硫化钼分别引入丁腈橡胶复合材料,考察四种固体润滑剂对复合材料性能,尤其是摩擦学性能的影响.结果表明,石墨烯的引入使丁腈橡胶复合材料的硬度及模量明显上升,扯断伸长率下降;而二硫化钼的引入有利于提高材料的撕裂性能.在干摩擦条件下,石墨烯的引入可有效提高材料的耐磨性并降低材料的摩擦系数,这得...     

纳米微粒作为润滑油脂添加剂的现状与发展趋势

通过对目前润滑油脂添加剂研究成果的综合分析,提出了当前研究中存在的一些问题以及今后应关注的研究方向,特别强调应重点加强特殊环境,如高温、重载、磨损表面的修复、环境友好等条件下的纳米润滑添加剂的研制,纳米微粒润滑机理与其特殊的摩擦学性能之间的关系,以及表面修饰纳米微粒的工业化研究。     

An investigation of the friction and wear behaviors of polyphenylene sulfide filled with solid lubricants

Composites of polyphenylene sulfide (PPS) filled with solid lubricant particles of graphite (C), molybdenum disulfide (MoS₂), and polytetrafluoroethylene (PTFE) were prepared by compression molding. The size of the solid lubricant particles was 3‐;5 µm. The friction and wear behaviors of the composites were examined with a pinon‐disk test rig. The worn composite pin surfaces and the transfer films formed on the counterface were analyzed with scanning electron microscopy. An X‐ray photo‐electron spectroscope (XPS) was used to characterize the chemical states of the elements in the transfer film. It has been found that graphite and PTFE as the fillers increase the wear resistance of PPS considerably, while MoS₂ as the filler decreases the wear resistance of PPS greatly. The fillers promote the decomposition of PPS and generate compounds, which accounts for the changes in the wear resistance of the composites.     

油酸改性石墨烯/二硫化钼复合材料润滑添加剂的制备及摩擦学特性

为研究石墨烯基二硫化钼复合材料润滑添加剂对10^#白油（10^# White Oil,10^# WO）的摩擦磨损性能影响。采用水热反应法,以油酸为改性剂,以硫化钠为硫源,制备出油酸改性还原氧化石墨烯/二硫化钼（OA-RGO-MoS₂,ORM）及还原氧化石墨烯/二硫化钼（RGO-MoS₂,RM）复合材料,利用四球长时摩擦磨损试验机考察ORM和RM对10^# WO润滑性能的影响,借助多种现代表征手段分别对两种复合材料和磨痕进行表征分析。研究结果表明：ORM较RM具有更大的层间距、更高的石墨化程度、更好的热稳定性以及更加优异的分散稳定性。两种复合材料均在质量分数为0.2%时体现出最优异的润滑性能,其中,ORM由于经过油酸改性,产生的空间位阻效应使其润滑性能更加突出,最优条件下平均摩擦系数下降了42.2%。摩擦机理分析表明：RM与ORM均可在摩擦过程中通过吸附作用或摩擦化学反应在摩擦表面形成含有铁、氧、钼、碳和硫元素的润滑保护膜,从而起到减摩抗磨的作用。     

网络互穿型碳化硅陶瓷/铁基复合材料制备及其耐磨性能

通过酚醛树脂固化、碳化及原位硅化的技术制备复杂形状SiC陶瓷,并利用金属浇注工艺制备出了以高锰钢、高铬铸铁为基体的2种网络互穿型SiC陶瓷/金属复合材料。借助湿式橡胶轮摩擦磨损试验机和UMT-3多功能摩擦磨损试验机测试该2种复合材料及2种基体的摩擦学性能,并采用扫描电子显微镜分析了复合材料和基体磨损后的表面形貌。结果表明：由于SiC陶瓷体的强度、硬度比金属基体高,导致在磨损过程中2种基体材料的磨损量较大,且在复合材料表面形成微凸起,使得复合材料的耐磨性能明显提高;SiC陶瓷/高铬铸铁复合材料的耐磨性优于SiC陶瓷/高锰钢复合材料,但SiC陶瓷/高锰钢复合材料的界面结合更好。