PTFE微粉/CF改性PEEK复合材料的摩擦磨损性能

为解决核电水循环系统中鼓型旋转滤网驱动装置的耐腐蚀问题,本文研究了碳纤维和聚四氟乙烯微粉改性的聚醚醚酮复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能.通过机械共混、高温模压的方法,制备了不同质量分数的聚四氟乙烯(PTFE)微粉/碳纤维(CF)/二硫化钼(MoS_2)/聚醚醚酮(PEEK)复合材料.采用拉伸试验机和塑料洛氏硬度计测试其力学性能,采用摩擦磨损试验机测试了复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能,采用扫描电子显微镜对其摩擦表面形貌进行分析.结果表明:复合材料在水润滑和油润滑时摩擦系数及磨痕宽度均较小,但水润滑时摩擦系数波动幅度较大且磨痕宽度略高;复合材料在干摩擦条件下的磨损机制以磨粒磨损为主,伴有疲劳磨损,油润滑时摩擦面可形成连续的润滑膜而保持光滑,水润滑时水流冲刷破坏了摩擦面上固体润滑膜的稳定性;CF质量分数增加时,复合材料的洛氏硬度和压缩强度递增,压缩强度达到164 MPa,PTFE微粉质量分数增加时,复合材料的洛氏硬度和压缩强度递减;CF质量分数增加时,复合材料的干摩擦系数及磨痕宽度下降,PTFE微粉质量分数增加时,复合材料的干摩擦系数下降,达到0.17.     

梯度自润滑复合材料在不同滑动摩擦下的摩擦学特性

梯度自润滑复合材料是一种新型润滑材料,利用粉末冶金工艺设计和制备了该材料,考察了其在不同摩擦条件下的摩擦学特性,并对其摩擦磨损机理进行了分析和研究.结果表明:梯度自润滑复合材料随着复合固体润滑剂含量的增多,摩擦学性能明显改善,但润滑剂含量过高将导致材料表面硬度过低;该材料适用于高载倚下的润滑部件;脂润滑条件下,复合固体润滑剂与润滑脂结合在摩擦面上形成的膏状润滑膜使梯度自润滑复合材料的摩擦学性能显著改善;在脂润滑高载荷条件下,梯度自润滑复合材料的磨损主要发生在磨损初期,之后磨损极小,摩擦系数也趋于减小.     

Microstructural investigation on antifriction characteristics of self-lubricating copper hybrid composite

Abstract

Owing to good antifriction properties and high wear resistance, copper hybrid composites reinforced with hard ceramic particles and solid lubricant components are regarded as promising materials for applications in sliding electrical contacts. The present work investigates the antifriction mechanism of a (SiC+Gr)/Cu composite from a microstructural viewpoint, so as to assist the development and application of this material. A graphite rich tribolayer formed on the worn surface was responsible for good tribological properties of the composites. Testing results showed that nanoparticles of graphite were involved in a mechanically mixing process by adhering to both the other wear debris and the two contacting surfaces, thereby developing a solid lubricant tribolayer. The nanographite to nanographite contacting mode, formed between the composite and the counterface, significantly improved wear resistance and friction stability. The forming and failure process of the graphite rich tribolayer was studied. A mechanism has been developed based on the experimental results.     

陶瓷的润滑问题

本文阐述了并分析了陶瓷材料的摩擦磨损、润滑研究现状，由于陶瓷的化学惰性，传统的润滑剂，添加剂在陶瓷表面的吸附力较弱，且很难在边界润滑下与表面发生摩擦化学反应形成极压润滑膜，传统润滑剂对陶瓷铁润滑效果与润滑金属相比要差科多，尽管在干摩时陶瓷材料磨损率比金属小得多，但仍比实际应用时要求的磨损率高必个量级。     

Tribological behavior of ZA27/Al2O3/graphite hybrid nanocomposites

ZA27 alloy composites reinforced with alumina and graphite nanoparticles are a unique class of advanced engineered materials that have been developed to use in tribological applications. In this study, dry sliding wear behavior of ZA27 alloy matrix hybrid nanocomposites has been investigated. Mechanical alloying and hot pressing methods have been used for the fabrication of these composite materials. Sliding wear tests were conducted using a block-on-disc type sliding wear testing apparatus under unlubricated conditions. Scanning electron microscopy analyses have been carried out to examine the wear surfaces. The results showed that the increase of alumina nanoparticle content can positively influence improvement of the tribological behavior of the hybrid nanocomposites.     

Microstructure,strength and tribological behavior of Fe–C–Cu–Ni sintered steels prepared with MoS<Subscript>2</Subscript> addition

Powder metal processing permits development of new composites with specific properties required for demanding applications. Complex shaped machine elements like gears and bearings are made of powder metallurgy technique economically. In many applications these machine elements operate under unlubricated conditions and there is a need for materials with good friction and wear characteristics, strength and modulus. In the present study, Fe–C–Cu–Ni alloys with solid lubricant, MoS₂, were developed using a simple single stage compaction and sintering. The microstructure, strength, hardness and tribo behavior of the composites were evaluated. The friction and wear characteristics were evaluated using pin-on-disc type tribo test machine. Addition of solid lubricant improved the compressibility and thereby the density of the compacts. Presence of the secondary sulphide phases in the as-sintered compacts improves the hardness and strength. The coefficient of friction and wear loss decreased with addition of MoS₂. A simple wear model is proposed to predict the wear loss in these composites. The model predicts wear loss values that are in agreement with the experimental data.     

高分子自润滑材料研究进展

高分子自润滑材料的基础和应用研究是摩擦学研究的热点之一.介绍了高分子基复合材料的磨损机理研究及固体润滑剂的发展和应用研究状况,综述了聚四氟乙烯(PTFE)、聚酰亚胺(PI)、聚醚醚酮(PEEK)、聚苯硫醚(PPS)、聚甲醛(POM)作为自润滑材料的研究应用进展,无机填料主要提高其硬度与耐磨性,而聚合物共混可改善纯树脂的热力学性能,复合材料摩擦磨损特性与在对偶面上形成转移膜的能力和转移膜特性相关.     

新型填料对高摩复合材料摩擦磨损性能影响及机制

采用干法热压成型工艺制备高摩复合材料,研究了基体材料腰果壳油改性酚醛树脂(CPR)与丁晴橡胶(NR)的质量比和新型高性能填料(主要成分为石墨粉Al2O3、MoS2、Fe粉)含量对高摩复合材料摩擦磨损性能的影响规律。在摩擦磨损试验机上测试了高摩复合材料的摩擦磨损性能,利用激光共聚焦显微镜、扫描电镜对摩擦表面形貌、磨屑进行观察和分析,借助EDS测定摩擦表面成分的变化。结果表明,随着CPR与NR质量比的增加,高摩复合材料的耐热性能、结合性能大幅提高,且具有较好的摩擦磨损性能。当高性能填料含量较低时,磨损表面出现大量连续的真实接触面,磨损机制为磨粒磨损和黏着磨损;当高性能填料含量较高时,真实接触面积减少,磨损表面剥落严重,并出现较多的裂纹,其主要磨损形式转变为磨粒磨损和疲劳磨损。随着高性能填料含量的增加,摩擦表面的元素从均匀分布逐渐转变为局部富集,磨粒的尺寸逐渐变大。     

SiC-Si合金化复相陶瓷干摩擦磨损性能的研究

在SiC-Si中加入Ni、Ti或B4C形成SiC-Si-Ni、SiC-Si-Ti及SiC-Si-B等复相陶瓷材料。研究了不同温度下的干摩擦磨损行为与机理。探讨了在摩擦表面形成固体润滑与液体润滑,以改善摩擦磨损性能的两种途径在SiC-Si复相陶瓷上实现的可行性。结果表明,通过摩擦反应在表面形成固体润滑膜,是改善SiC-Si复相陶瓷干摩擦性能的有效途径。     

稀土处理玻璃纤维填充PTFE复合材料的滑动磨损性能

研究了不同玻璃纤维表面处理对PTFE复合材料在干摩擦条件下滑动磨损性能的影响,并借助扫描电子显微镜(SEM)分析了磨损机理。结果表明:在干摩擦条件下,经表面处理玻璃纤维填充的PTFE复合材料的摩擦系数和摩擦表面温度比未经处理玻璃纤维填充的PTFE复合材料的低,且减磨性能优于未经处理的;而稀土处理玻璃纤维填充的PTFE复合材料的摩擦系数和摩擦表面温度最低,减磨性能最好;未经处理玻璃纤维填充的PTFE复合材料和偶联剂处理玻璃纤维填充的PTFE复合材料都发生了剧烈的粘着转移;偶联剂与稀土处理玻璃纤维填充的PTFE复合材料的磨损机理主要是明显的磨粒磨损;稀土处理玻璃纤维填充PTFE复合材料的磨损形式主要是粘着转移和轻微的磨粒磨损。     

Synergism of several carbon series additions on the microstructures and tribological behaviors of polyimide-based composites under sea water lubrication

The effects of several carbon series additions including graphite (Gr), carbon fiber (CF) and carbon nanotube (CNT) on the microstructures and tribological behaviors of polyimide-based (PI-based) composites under sea water lubrication were investigated systematically. Results showed that the incorporation of any filler improved the wear resistance of polyimide (PI) under sea water lubrication, but did not decrease the friction coefficient. Especially the combined incorporation of 10%Gr, 10%CF and 5%CNT (in volume) was the most effective in improving the anti-wear properties of PI. This suggested that there existed a synergetic effect among the three carbon series additions on improving the wear resistance of PI. During the friction and wear process, the carbon additions played different roles in improving the wear resistance of PI-based composites. CF with high compressive strength can carry the main load applied on the sliding surfaces to inhibit the wear of PI matrix. CNT can decrease the stress concentration around CF and further protect CF from being broken. Gr in the form of much thinner layer can not only improve the loading capacity, but also play the same role of CNT to avoid CF carrying too much load. More importantly, Gr, CF and CNT worked synergistically to condense the microstructure of PI-based composite and ameliorate the interfacial combination between all fillers and PI matrix, which well explained why the PI–10%Gr–10%CF–5%CNT composite had excellent tribological properties, even under heavy load or high sliding speed.     

Friction and wear properties of UHMWPE composites reinforced with carbon fiber

The artificial joint acetabular material ultrahigh molecular weight polyethylene (UHMWPE) was reinforced with carbon fibers (CF) in different contents. The effects of CF content on hardness and tribological properties of the materials were studied. The morphologies of wear surfaces were examined with a Scanning Electron Microscope (SEM). The results show that the hardness and wear resistance of CF-reinforced UHMWPE composites increased with CF content; the friction coefficients under distilled water lubrication were decreased greatly by the addition of CF; that adherence, plowing, plastic deformation and fatigue wear are dominant for the UHMWPE under dry sliding, and that abrasive wear and drawing out of CF from the wear surface of the composites are dominant for the CF-UHMWPE composites under both dry and distilled water lubrication conditions.     

Synthesis and tribological behavior of metakaolinite-based geopolymer composites

Metakaolinite-based geopolymer composites containing 5%–30% (volume fraction) scalelike graphite, polytetrafluoroethylene (PTFE), and molybdenum disulfide (MoS₂), respectively, were synthesized in the presence of a compound activator composed of aqueous NaOH and sodium silicate at room temperature. The tribological behaviors of the resulting composites sliding against AISI-1045 steel were investigated on an MM-200 friction and wear tester, and the bending strength and compressive strength of the composites were determined on a universal materials tester. Moreover, the worn surfaces of the composites were analyzed by means of scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS), which was aimed to reveal the wear mechanisms of the composites. It was found that all the three kinds of the tested solid lubricants contributed to greatly decrease the friction and wear of the composites, and they were also able to remarkably reduce the fluctuation of the friction coefficient. This was attributed to the formation of a lubricating film containing higher content of the detached solid lubricant particulates and the oxidized product Fe₂O₃ of the counterpart steel wear debris. The metakaolinite-based geopolymer was dominated by severe adhesion wear, while its composites filled with the solid lubricant particulates were characteristic of mild adhesion, scuffing, and delamination.     

粉煤灰增强MC尼龙复合材制备与性能研究

为提高MC尼龙的综合性能,在己内酰胺熔融单体中加入粉煤灰,通过碱催化阴离子聚合反应制备粉煤灰增强尼龙复合材料(FMCPA),采用扫描电镜和拉伸实验对复合材料的显微组织进行了观察和分析,并对其力学性能和摩擦性能进行了测试.结果表明,原状粉煤灰经活化处理后变得均匀细小,但与基体间存在明显的界面空隙,而经活化偶联处理的粉煤灰均匀分布在复合材料中,与尼龙基体的界面结合良好.复合材料的拉伸断面有明显的牵引痕迹,粉煤灰颗粒起到钉紧作用.粉煤灰质量分数较低时,尼龙复合材料以粘着磨损为主,伴有磨粒磨损;随着粉煤灰质量分数的增加,磨粒磨损加重.粉煤灰的加入提高了复合材料的力学性能,同时改善其耐磨损性能,当粉煤灰质量分数为20%时复合材料的综合性能最好.     

MAX相增强金属基复合材料的研究现状及应用

Mn+1AX_n(简称MAX)为一种三元层状材料,当其作为金属基复合材料的增强项时,可使复合材料具有优异的力学性能和摩擦学性能,拓展了金属基复合材料的种类和应用范围。本文对MAX相的应用与性能进行了介绍,总结了MAX相增强金属基复合材料的界面对复合材料导电性和力学性能的影响,并对MAX增强金属基复合材料的摩擦学行为进行了综述,同时总结了MAX相作为增强相在协同摩擦、单相摩擦和高温摩擦中的磨损机理。最后对MAX相未来研究方向进行了展望。     

Experimental analysis of nanomechanics of spherical titanium oxide nanooils in reducing friction

This work explores the nanomechanics of sphere titanium oxide nanooils in reducing friction between two pieces of cast iron. A friction test is performed using an ATE-77 Reciprocal Tribological Tester made by Cameron-Plint Tribology Limited, England. The friction between two pieces of cast iron was determined 25-135 degrees C using home-made titanium oxide nanooils. In elastohydrodynamic lubrication (EHL), the lubricant is subjected to enormous pressures, there is considerable local heating, and the assumption of constant viscosity no longer holds up. The derivation of the governing equations for elastohydrodynamic lubrication, the pressure and temperature dependence of viscosity is recognized after the lubrication thin film approximation has been made. The viscosity of the nanooils consistently exceeded that of the paraffin oil enlarging the partial EHL area with a complete lubricating film between two move iron surfaces. The spherical geometry of TiO2 nanoparticles caused them to act as a rolling medium when the machine parts move which is in the solid friction area. Because they provide a rolling function, spherical titanium oxide nanoparticles have feasible tribological and lubrication applications in the mechanical industry to reduce noise, vibration and friction wear.     

Al2O3—TiC—Co复合材料的单磨粒摩擦和磨损

用扫描电镜中的摩擦磨损原位观察装置研究Ａｌ２Ｏ３－ＴｉＣ－Ｃｏ复合材料在单磨粒作用下的摩擦磨损性能。     

Solid lubricants: a review

The fundamental mechanisms of solid lubrication are reviewed with examples from well-known solid lubricants like the transition metal dichalcogenides and diamond-like carbon families of coatings. Solid lubricants are applied either as surface coatings or as fillers in self-lubricating composites. Tribological (friction and wear) contacts with solid lubricant coatings typically result in transfer of a thin layer of material from the surface of the coating to the counterface, commonly known as a transfer film or tribofilm. The wear surfaces can exhibit different chemistry, microstructure, and crystallographic texture from those of the bulk coating due to surface chemical reactions with the surrounding environment. As a result, solid lubricant coatings that give extremely low friction and long wear life in one environment can fail to do so in a different environment. Most solid lubricants exhibit non-Amontonian friction behavior with friction coefficients decreasing with increasing contact stress. The main mechanism responsible for low friction is typically governed by interfacial sliding between the worn coating and the transfer film. Strategies are discussed for the design of novel coating architectures to adapt to varying environments.     

碳纤维及石墨填充聚四氟乙烯复合材料的摩擦学性能研究

利用M-200型环-块摩擦磨损试验机对石墨(Gr.)及碳纤维(CF)填充聚四氟乙烯(PTFE)复合材料的摩擦磨损性能进行了研究,探讨了石墨及碳纤维的协同润滑效应.认为碳纤维的加入大大提高了复合材料的承载能力,石墨的加入减小了碳纤维表面与对偶的摩擦系数,从而降低了碳纤维的脱落趋势,提高了复合材料的耐磨性.利用扫描电子显微镜(SEM)对PTFE复合材料的摩擦面及对偶转移膜进行了观察.结果表明,本实验中20%的石墨和10%碳纤维填充PTFE复合材料的摩擦磨损性能最好,且在高载荷下的摩擦磨损性能尤为突出,具有一定的应用价值.     

Tribological behavior of aluminum-CNT coated metal composite under dry and water lubricated conditions

Carbon nanotubes are considered the best material in the field of composites because of their mechanical and tribological properties. In this study, carbon nanotubes coated metal was dispersed in aluminum, the base metal, to improve the wettability between aluminum and carbon nanotubes. The friction and wear behaviors of the aluminum-carbon nanotube coated metal, which is a nickel and copper composite, were investigated using a pin-on-disk wear tester under dry sliding and water lubricated conditions and evaluated using SEM and EDX analysis. All the results demonstrated that the addition of the carbon nanotubes coated metal significantly improved the wettability of CNTs in the aluminum. And the distribution of CNTs prevented the propagation of micro cracks on the surface of the aluminum base metal sample, resulting in enhanced friction characteristics and wear resistance of the nano composite. The composite exhibited lower friction coefficient and wear resistance under the water lubricated condition than the dry sliding condition. Although the lubrication and cooling effect of water contributed to the reduction of the friction coefficient of the composite, the separation of wear particles from the sliding surface changed the wear type from three-body to two-body, resulting in very high wear rate. Also the concentration of oxide under water lubricated condition contributed to the increase of the wear rate because the amount of oxide film removed in terms of thickness exceeded the critical thickness of real contact area.