Tribological Properties of TiAl Matrix Self-Lubricating Composites Containing Multilayer Graphene and Ti3SiC2 at High Temperatures

An investigation is conducted on the unexplored synergistic effects of multilayer graphene (MLG) and Ti₃SiC₂ in self-lubricating composites for use in high-temperature friction and wear applications. The tribological properties of TiAl matrix self-lubricating composites with different solid lubricant additions (Ti₃SiC₂-MLG, MLG) are investigated from room temperature to 800°C using a rotating ball-on-disk configuration. Tribological results suggest the evolution of lubrication properties of MLG and the excellent synergistic lubricating effect of MLG and Ti₃SiC₂ as the testing temperature changes. It can be deduced that MLG has great potential applications as a promising high-temperature solid lubricant within 400°C, and a combination of MLG and Ti₃SiC₂ is an effective way to achieve and maintain desired tribological properties over a wide temperature range.     

Dry-Sliding Tribological Properties of TiAl/Ti2AlC Composites

The microstructure, mechanical and dry-sliding tribological properties of TiAl-based composites with 20 and 40 vol% in situ formed Ti₂AlC, produced by hot press sintering process, are investigated. The microstructural characterization reveals that Ti₂AlC phase is in the form of spherical particles and large blocks, and the quantity of the blocks increases with Ti₂AlC content. This difference in the morphology and distribution of the Ti₂AlC phase leads to the discrepancy of the wear resistance of the composites. In contrast to the Ti-46Al-2Cr-2Nb intermetallics, the dry-sliding wear resistance of the TiAl/Ti₂AlC composites first declines slightly and then enhances with the Ti₂AlC content. Furthermore, the TiAl/40 % Ti₂AlC composite shows low wear rate at higher sliding speed.     

Effect of Sliding Speed and Applied Load on Dry Sliding Tribological Performance of TiAl Matrix Self-lubricating Composites

More durable, low-friction self-lubricating materials in modern industry are greatly needed for tribological systems. The current paper presents the tribological performance of TiAl matrix self-lubricating composites (TSC) containing MoS₂, hexagonal BN and Ti₃SiC₂ designated as MhT against GCr15 steel counterface under several sliding speeds from 0.2 to 0.8 m s^?1 and applied loads from 6 to 12 N. The results suggested that MhT played an important role in decreasing friction coefficients and wear rates. The covering percentage of transfer layers on worn surfaces varied with the changing of sliding speeds and applied loads, hence resulting in the distinct friction and wear characteristics of TSC. TSC containing 10 wt% MhT exhibited the best excellent tribological performance at 10 N–0.8 m s^?1, which could be due to the formation of the best compaction and largest coverage of transfer layer on the worn surfaces.     

Tribological Behavior of Ti3AlC2 Against SiC at Ambient and Elevated Temperatures

In this paper, we reported the tribological behavior of Ti₃AlC₂ disk sliding against SiC ball from room temperature (RT) to 1,000 °C. The tribological properties are highly dependent of testing temperature. At RT, the coefficient of friction (CoF) is as low as 0.34 in the steady state, but the wear rate is relative high (4.26 × 10^?4 mm³/Nm). At 200 and 400 °C, the CoF is as high as 1.21, and the wear rates are very high, about on the order of 10^?3 mm³/Nm. From 600 to 1,000 °C, however, Ti₃AlC₂ exhibits quite low wear rate on the order of 10^?6 mm³/Nm and relative moderate CoF, 0.60–0.80. The compacted continuous oxide layer at 600 °C and above might be responsible for the outstanding wear resistance.     

Enhanced Mechanical and Tribological Properties of Graphene-Reinforced TiAl Matrix Composites

This study investigated the mechanical properties and dry-sliding friction and wear behaviors of graphene-reinforced TiAl matrix composites in expectation of providing valuable information for the application of graphene. The results suggested that the incorporation of graphene apparently improved the microhardness, fracture toughness, and tribological properties of the composites. For the composite with 3?wt% graphene, the microhardness increased by 129%, the fracture toughness increased by 149%, the friction coefficient decreased by 37% and the wear rate decreased by 78%. Also, the microstructural analyses of the worn surfaces indicated that three types of graphene-rich films, with different percentages of coverage, were generated on the worn surfaces under various wear conditions. An evolution mechanism of the films as a function of wear conditions was proposed, and the corresponding variation of friction and wear behavior was also discussed.     

锡青铜基自润滑复合材料摩擦磨损性能研究

采用冷压烧结方法制备了短碳纤维增强锡青铜基自润滑复合材料和ZQSn663锡青铜,对其力学性能及摩擦磨损性能进行了对比研究,并对磨损机制进行了讨论.结果表明,当碳纤维体积分数小于12%时,锡青铜自润滑复合材料的力学性能优于ZQSn663锡青铜,磨损率和摩擦因数低于ZQSn663锡青铜.当碳纤维体积分数达到12%时,复合材料的摩擦磨损性能达到最佳.扫描电镜和EDS分析结果表明,ZQSn663锡青铜的磨损是以粘着和磨粒磨损共存的机制,以粘着磨损为主;锡青铜自润滑复合材料的磨损是粘着磨损和氧化磨损共同作用的结果.     

Wear and Friction of TiAl Matrix Self-Lubricating Composites against Si3N4 in Air at Room and Elevated Temperatures

More durable, low-friction bearing materials over a wide temperature range are needed for turbine components and other high-temperature bearing applications. The current study reported the tribological properties of TiAl matrix self-lubricating composites (TMC) containing MoS₂ (a low-temperature lubricant, below 500°C), hBN (a medium-temperature lubricant, below 600°C), and Ti₃SiC₂ (a high-temperature lubricant, above 600°C) designated as MhT against an Si₃N₄ counterface at temperatures ranging from 25 to 800°C in air. The load was 10 N and the sliding speed was 0.2 m/s for all tests. Tribological studies indicated that TMC containing MhT showed a lower friction coefficient and wear rate in comparison to TiAl-based alloy at all test temperatures, which was attributed to the excellent synergetic lubricating effect of MoS₂, hBN, and Ti₃SiC₂. TMC containing 5 wt% MhT exhibited the best tribological properties over a wide temperature range.     

Tribological Properties of Adaptive Ni-Based Composites with Addition of Lubricious Ag2MoO4 at Elevated Temperatures

The Ni-based self-lubricating composites with addition of 10 and 20?wt% Ag₂MoO₄ were fabricated by powder metallurgy technique, and the effect of Ag₂MoO₄ on tribological properties was investigated from room temperature to 700?°C. The tribo-chemical reaction films formed on rubbing surface and their effects on the tribological properties of composites at different temperatures were addressed according to the surface characterization by SEM and Micro-Raman. The results show that the Ag₂MoO₄ decomposed into Ag and Mo during the high-temperature fabrication process. The friction coefficient and wear rate of the composites decrease with the increasing of temperature and Ag₂MoO₄ contents and the composites with addition of 20?wt% Ag₂MoO₄ exhibits the lowest friction coefficient (0.26) and wear rate (1.02?×?10^?5?mm³?N^?1?m^?1) at 700?°C. The composition of the tribo-layers on the worn surfaces of the composites is varied at different temperatures. It is proposed that the improving of tribological properties of the composites at high temperatures are attributed to the synergistic lubricating effect of silver molybdate (reproduced in the rubbing process at high temperatures) and Fe oxide (transfer from disk material to the pin) formed on the worn surface.     

Tribological Properties of PTFE and PTFE Composites at Different Temperatures

The friction and wear properties of polytetrafluoroethylene (PTFE) and its composites with fillers such as bronze, glass fiber, carbon fiber, carbon, graphite, and polymer were studied at ambient temperature and high temperature. The wear resistance and hardness were enhanced by the fillers. Results showed that the wear resistance of all composites was much higher than that of pure PTFE. Pure PTFE has the lowest friction coefficient at ambient temperature (temperature: 23 ± 2°C, humidity: 50 ± 10%) but highest friction coefficient at high temperature (above 100°C). The PTFE composite filled with bronze showed the best wear resistance at ambient temperature but the poorest wear resistance at high temperature. The carbon-graphite- or polymer-filled PTFE composite showed a lower friction coefficient and moderate wear resistance at both ambient and high temperature.     

铝-塑自润滑材料的结构分析设计与摩擦磨损性能

对高强铝合金(7075)———超高分子量聚乙烯(UHMWPE)自润滑材料进行结构分析设计,通过压缩试验与往复式滑动摩擦磨损试验测试了新材料的承载力、摩擦热、摩擦因数与磨损率;用扫描电镜观察了磨损表面的磨痕形貌并分析了磨损机理。结果表明:这种新型自润滑材料的比强度较高,抗压强度达到100MPa,摩擦因数小于0.16;在正压力P=8.5kN、往复频率300次/min(30mm/s)、滑动行程S=324m的室温干摩擦条件下,磨损率为1.7×10-6mm3/(N.m),摩擦温度为65℃;这种新型自润滑材料在磨合期主要表现为犁沟和粘着磨损,磨损后期表现为表层和亚表层的脆性断裂。     

Ti3SiC2/SiC复相陶瓷/45#钢摩擦副的摩擦学性能

研究了由热等静压原位合成的Ti3SiC2/SiC复相陶瓷与45#钢在干摩擦和边界油润滑条件下的摩擦磨损特性.结果表明：干摩擦条件下随载荷的变化,占主导地位的磨损机制将发生变化,在低载荷下以磨粒磨损为主,高载荷下以粘着磨损为主;同干摩擦相比,润滑油对摩擦副的摩擦磨损性能的改善均很显著;Ti3SiC2/SiC复相陶瓷的磨损主要由粘着和微断裂引起的.     

Tribo-oxidation of Self-mated Ti3SiC2 at Elevated Temperatures and Low Speed

The tribological behavior of self-mated Ti₃SiC₂ is investigated from ambient temperature to 800?°C at a sliding speed of 0.01?m/s in air. The results show that at the temperatures lower than 300?°C, friction coefficient and wear rates are as high as 0.95 and 10^?3?mm³/N?m, respectively. With the temperature increasing to 600?°C, both the friction coefficient and wear rates show consecutive decrease. At 700 and 800?°C, friction coefficient and wear rates are 0.5 and 10^?6 mm³/N?m, respectively. According to the wear mechanism, the tribological behavior of Ti₃SiC₂ can be divided into three regimes: mechanical wear-dominated regime from ambient temperature to 300?°C characterized by pullout of grains; mixed wear regime (mechanical wear and oxidation wear) from 400 to 600?°C; and tribo-oxidation-dominated wear regime above 700?°C. The tribo-oxides on the worn surfaces involve oxides of Si and Ti. And, species transformation occurs to these two oxides with the increasing temperature. In the competition oxidation of elements Ti and Si, Si is preferably oxidized because of its high active position in the crystal structure. Additionally, plastic flow is another notable characteristic for the tribological behavior of self-mated Ti₃SiC₂.     

PEEK基自润滑复合材料的摩擦学研究和应用

聚醚醚酮(PEEK)基自润滑复合材料具有摩擦因数低、耐磨性好等特点,可以在无润滑、高温、潮湿、污染、腐蚀等恶劣环境下使用。本文综述了对聚醚醚酮(PEEK)基复合材料摩擦学研究的新进展,讨论了纤维增强、无机填充、有机共混改性以及温度、对偶和介质、固体润滑剂等对PEEK基复合材料摩擦学性能的影响,介绍了PEEK基复合材料在人工关节假体材料方面的应用,指出PEEK摩擦复合材料今后的研究方向,以期扩大PEEK复合材料的摩擦学工程应用。     

碳织物增强聚合物基自润滑材料摩擦学性能研究进展

从聚合物基体、组分改性、碳织物增强工艺、材料摩擦磨损机制等方面综述碳织物增强树脂基自润滑复合材料摩擦学研究现状。比较热塑性与热固性树脂基体在该类材料中的应用特点,介绍聚合物本体改性和减摩增强填料改性提高摩擦学性能的各种方法,总结当前摩擦学研究中碳织物增强制备工艺及典型材料的摩擦学性能,指出减摩机制、磨损形式、摩擦温升为该类材料摩擦学性能研究中关注的焦点。温度范围广、力学性能优良、易加工成型、无污染的新型材料与成型工艺为今后碳织物增强聚合物基自润滑复合材料摩擦学研究中的首选。     

SiC长纤维增强Ti基复合材料的制备

Si C长纤维增强 Ti基复合材料在航空领域有广阔的应用前景 ,本文对其制备方法进行了评述。比较了箔 -纤维法、浆料带铸造法、等离子喷涂法及纤维涂层法制备 Ti基复合材料的优缺点及制备成本 ,认为采用纤维涂层法制备 Ti基复合材料航空发动机零部件较好。本文还用纤维涂层法制备了 SCS- 6 Si C/Ti- 10 2 3复合材料试样     

La2O3对铜基自润滑复合材料高温摩擦磨损性能的影响

为进一步提高铜基自润滑复合材料的硬度和高温摩擦磨损性能,采用粉末冶金热压法向铜-石墨烯-WS2复合材料中引入La2O3增强相颗粒,并对铜-石墨烯-WS2复合材料和La2O3增强铜-石墨烯-WS2复合材料在不同温度下的摩擦磨损性能进行对比研究。结果表明:复合材料烧结过程中各组元没有发生分解或互相反应,烧结后材料结构致密并且各组元均匀分布于基体中,La2O3增强相的引入在提高复合材料硬度的同时会降低材料热导率;室温下2种复合材料摩擦因数和磨损率比较相近,而高温下石墨烯和WS2的氧化导致Cu-RGO-WS2复合材料摩擦磨损性能下降,而La2O3则能发挥增强相作用和高温自润滑作用,使Cu-RGO-WS2-La2O3复合材料的高温摩擦磨损性能更优异。室温下铜-石墨烯-WS2复合材料的磨痕处仅发生了轻微的塑性变形,而La2O3增强铜-石墨烯-WS2复合材料的磨损机制主要是磨粒磨损;高温下铜-石墨烯-WS2复合材料的磨损机制为黏着磨损,而La2O3增强铜-石墨烯-WS2复合材料的磨损机制则为磨粒磨损和疲劳磨损。     

Tribological Behavior and Tribochemistry of Self-mated Ti3SiC2 in Ethanol

The tribological behavior of self-mated Ti₃SiC₂ in low viscosity fluids, that is, water and ethanol, is investigated. The results show that both water and ethanol effectively reduce the friction and wear of self-mated Ti₃SiC₂. The friction coefficient and total wear rates of Ti₃SiC₂ tribo-pair are 0.82 and 2.17 × 10^?2 mm³/N m under dry condition, 0.41 and 6.50 × 10^?4 mm³/N m in water and 0.16 and 2.22 × 10^?4 mm³/N m in ethanol. As sliding distance is prolonged from 0.5 to 22.9 km, the total wear rates of Ti₃SiC₂ in ethanol can be further reduced. Mechanical wear of Ti₃SiC₂ is partly inhibited in water and greatly inhibited in ethanol. Surface polishing of Ti₃SiC₂ pin and tribochemistry are the two distinct characteristics of self-mated Ti₃SiC₂ in ethanol. The surface film in ethanol is composed of TiO₂ and SiO. Tribo-products in ethanol, that is, silica gel and titanium dioxide, are found. Polycondensation of ethanol by the catalysis of TiO₂ and SiO_2?x gives birth to paraffins and olefins.     

原位合成钛基复合材料的高温力学性能

利用钛与B4C反应经普通的熔铸工艺制备了原位合成TiB和TiC增强的钛基复合材料。研究了原位合成钛基复合材料的高温力学性能和断裂机理。结果表明：随着温度的升高，其抗拉强度降低，伸长率提高。但与基体钛合金比较，由于原位合成增强体非常稳定，能有效地强化基体合金，明显提高了复合材料的高温抗拉强度。拉伸断裂机理与温度有关，室温时，增强体断裂是材料失效的主要原因；而随着温度的提高，增强体与基体合金界面脱粘成为材料失效的主要原因。     

油介质对聚四氟乙烯纤维织物自润滑复合材料摩擦学性能的影响

采用栓-盘式摩擦磨损试验机研究航空煤油和液压油介质对聚四氟乙烯纤维织物自润滑复合材料的摩擦磨损性能的影响;利用扫描电子显微镜(SEM)观察和分析复合材料磨损表面形貌,并分析探讨摩擦磨损机制。结果表明,油介质的存在可明显降低复合材料的耐磨性能和极限承载能力,其中液压油的影响更为显著;介质浸泡处理的复合材料在摩擦过程中,磨损形式由黏着磨损逐步过渡到疲劳磨损,并且界面结合强度降低,导致材料耐磨性能下降。     

Tribological Behavior of Novel Ti3SiC2 (Natural Nanolaminates)-Reinforced Epoxy Composites during Dry Sliding

In this article, we report for the first time the synthesis and characterization of Ti₃SiC₂–epoxy (MAXPOL) composites. Three novel composites were designed by adding 20.7, 30.6, and 71.6 vol% Ti₃SiC₂ particulates to an epoxy matrix. The microstructure evaluation by scanning electron microscopy (SEM) showed that the Ti₃SiC₂ particles are well dispersed in the epoxy matrix. The addition of Ti₃SiC₂ enhanced the ultimate yield strength (UYS) and hardness of all of the composites compared to epoxy. Tribological studies were performed by a tab-on-disc method against Inconel 718 and alumina substrates. In both cases, the mean friction coefficient (µ_mean) decreased as the concentration of Ti₃SiC₂ in the epoxy matrix was increased. The concomitant wear rates (WRs) also decreased steadily and then increased slightly after reaching a concentration of ~32.6 vol% Ti₃SiC₂. The tribological studies proved conclusively that the addition of Ti₃SiC₂ in the epoxy matrix imparts self-lubricity to the composites. The tribofilms formed on different tribosurfaces were also characterized by detailed SEM investigations.