Friction and wear of fiber reinforced polyimide composites in electron or proton irradiation

The polyimide (PI) composites reinforced with carbon fibers, glass fibers, and aramid fibers were fabricated by means of a hot‐press molding technique and irradiated by electron or proton for a certain time. The friction and wear behavior after irradiation, sliding against GCr15 steel balls, were evaluated in a ground‐based simulation facility using ball‐on‐disk tribosystem. The change of the chemical composition of the radiated surface was examined by X‐ray photoelectron spectroscopy. The worn morphologies and radiated surfaces of the materials were observed by scanning electron microscope to reveal the wear mechanism. Experimental analysis indicated that the chemical composition of the materials changed and an irradiated layer was formed at the surface. This irradiation layer had an important effect on the friction and wear behavior of the PI composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40774.     

Friction and wear properties of basalt fiber reinforced/solid lubricants filled polyimide composites under different sliding conditions

Short basalt fibers (BFs)‐reinforced polyimide (PI) composites filled with MoS₂ and graphite were fabricated by means of hot‐press molding technique. The tribological properties of the resulting composites sliding against GCr15 steel ring were investigated on a model ring‐on‐block test rig. The wear mechanisms were also comparatively discussed, based on scanning electron microscopic examination of the worn surface of the PI composites and the transfer film formed on the counterpart. Experimental results revealed that MoS₂ and graphite as fillers significantly improved the wear resistance of the BFs‐reinforced polyimide (BFs/PI) composites. For the best combination of friction coefficient and wear rate, the optimal volume content of MoS₂ and graphite in the composites appears to be 40 and 35%, respectively. It was also found that the tribological properties of the filled BFs/PI composites were closely related with the sliding conditions such as sliding speed and applied load. Research results show that the BF/PI composites exhibited better tribological properties under higher PV product. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of cenosphere on tribological properties of short carbon fiber reinforced PEEK composites

This investigation focuses on the effects of cenosphere fillers on tribological properties of carbon fiber reinforced PEEK composites. Dry sliding wear behavior of 15 wt % short carbon fiber (SCF) reinforced PEEK composites filled with 5, 10, 15, and 20 wt % cenosphere was reported in this study, pure PEEK and 15 wt % SCF reinforced PEEK composites were also prepared for comparative analysis. Friction and wear experiments were conducted on a ring-on-block apparatus under different loads (100–400 N). The experimental results showed that all the composites exhibited lower coefficient of friction and better wear resistance than the matrix resin under different load conditions. It is noted that 10 wt % of the cenosphere particles filled SCF reinforced PEEK composites show superior tribological properties when compared to the other composites in this study. The morphologies of the worn surface and the fracture surface were analyzed by scanning electron microscopy and the transfer film was observed by optical microscope to understand the dominant wear mechanisms. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47245.     

Effect of degree of cure and fiber content on the mechanical and dynamic mechanical properties of carbon fiber reinforced PMR-15 polyimide composites

A unidirectional continuous carbon fiber reinforced polyimide composite is fabricated using the PMR-15 polyimide as a matrix. Mechanical and dynamic mechanical properties of the composite are studied. The effect of variation of the fiber content ranging from 55% to 70% by volume on the properties of the composite is determined. The effects of the laminate thickness and degree of curing of the matrix on the Izod impact strength are examined. The effect of the degree of curing of the matrix on the dynamic mechanical spectrum is studied. Finally, variables such as humidity, environment temperature, vacuum, and pressure during laminate processing, and variation of monomer composition are discussed in terms of change in matrix structure, which is reflected in a variation of Tg between batches.     

Epoxy composite reinforced with three‐dimensional polyimide fiber felt: Fabrication and tribological properties investigation

Novel epoxy (EP) composite reinforced with three‐dimensional (3D) polyimide (PI) fiber felt (PI_3D/EP) is first fabricated by vacuum assisted resin transfer molding. The tribological behaviors of pure EP and PI_3D/EP composite under dry sliding and water lubricated condition are comparatively studied. Results indicate that both wear rates and friction coefficients of PI_3D/EP composite are lower than those of pure EP. The wear resistance of PI_3D/EP composite is 9.8 times higher than that of pure EP under dry sliding of 1.5 MPa and 0.76 m s^?1 while a 27‐fold increase is achieved under water lubricated condition. The wear mechanisms of PI_3D/EP composite are investigated based on tribological testing results and scanning electron microscopy observations. The PI fiber felt provides strong 3D structure supports to sustain most of the loads on the composite, improving the mechanical and tribological properties significantly. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44160.     

Study on wear and friction behavior of graphite flake‐filled PTFE composites

The wear rate and coefficient of friction for graphite flake (GF)‐filled polytetrafluoroethylene (PTFE) composites were evaluated on a pin‐on‐disk wear tester under dry conditions. Scanning electron microscopy showed significant reduction in the abrasive wear of the composites. The wear rates of 5 and 10 wt % GF composites were reduced by more than 22 and 245 times, respectively, at sliding speed of 1 m/s. With increasing sliding distance from 1 to 8 km, the wear rate of pure PTFE decreased by 1.4 times whereas that of composites, it decreased up to three times. The significant decreased in wear rate and coefficient of friction might be attributed to the formation of a thin and tenacious transfer film on the counter‐surface. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Microhardness of carbon fiber reinforced epoxy and thermoplastic polyimide composites

We have examined the micro indentation hardness of a series of carbon fiber reinforced epoxy and thermoplastic polyimide (TPI) composites. In the epoxy systems, the influence of Nylon particles was studied. The effect of crystallization of the thermoplastic polyimide upon the microhardness values of the resin was also investigated. The microstructure of the TPI-composites was characterized by X-ray diffraction. The results show that the addition of carbon fibers to the neat resins greatly increases the microhardness and thus the yield stress of the composite. The value of the microhardness technique is highlighted in emphasizing the heterogeneity of the CFRC.     

Effect of atomic oxygen on corrosion and friction and wear behavior of polyimide composites

Thermosetting polyimide (TPI) composite with better wear resistance and lower friction was obtained with various functional fillers after a high–low temperature cycle test. Nevertheless, taking into consideration of harsh space condition, the friction and wear behavior of TPI composite were also explored after atomic oxygen (AO) irradiation. It reveals that TPI composite behaves excellent properties against AO mainly attributed to g-C₃N₄ with more negative electronegativity N than carbon atom. Moreover, the mechanism of friction and wear demonstrated that degradation caused by AO led to TPI composite surface with special “carpet-like” morphology and this resulted into lubrication failure, especially when temperature was increased from 200 °C to 350 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48441.     

Improved tribological properties of polyimide composites by micro–nano reinforcement

The hydroxylate carbon nanotubes (CNTs) were grafted by chemical method on the surface of the oxidized carbon fibers (CF) to improve the mechanical and tribological properties of polyimide (PI). The microstructure and fracture surface of the polyimide composites indicated that CF–CNTs hybrid as a multiscale reinforcement can distribute into the PI matrix homogeneously. Tribo-tests further showed that CF–CNTs hybrid had a better effect on hardness increment, impact strength enhancement, friction reduction, and wear resistance. Compared to the neat PI, the friction coefficient and wear rate of CF–CNTs/PI composite deceased by 23.2 and 55.9%, respectively. In particular, the loading capacity and high speed resistance of CF–CNTs/PI composite were greatly improved. The corresponding wear mechanisms were also discussed by observing the worn surface of the PI composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47900.     

短切碳纤维及碳纤维布增强硅橡胶复合材料的制备及力学性能

将短切碳纤维(CF)、白炭黑和甲基乙烯基硅橡胶(VMQ)共混后,与碳纤维布(CFC)复合制备VMQ复合材料.考察了CFC层数对复合材料的拉伸性能、邵尔A硬度、耐磨性能及动态力学性能的影响.结果表明,随着CFC层数的增加,复合材料的扯断伸长率基本不变,拉伸强度逐渐升高.与仅添加10份(质量,下同)CF的复合材料相比,加入...     

多壁碳纳米管/聚酰亚胺复合材料制备及其性能研究

聚酰亚胺的前聚体,聚酰胺酸,是通过4,4-二氨基二苯醚(ODA)与3,3,4,4二苯甲酮四羧酸二酐(BTDA)反应制备的.未改性的、酸改性和胺改性的多壁碳纳米管(MWCNT)被分别地单独加入到聚酰胺酸溶液中,并加热至300℃,从而制成聚酰亚胺/碳纳米管复合材料.扫描型电子显微镜(SEM)和透射电子显微镜(TEM)的显微...     

Effect of surface modification of Kevlar fibre on friction and wear properties of UHMWPE composites

Abstract

The effects of Kevlar fibre additions and, particularly, the surface modification of the Kevlar fibres, on the sliding wear behaviour of the ultra high molecular weight polyethylene (UHMWPE) composites were investigated. The results showed that the sliding friction coefficient of the UHMWPE composites increased with the fibre content increase. The wear resistance of the UHMWPE composite was highest when the Kevlar fibre content was ～10 vol.-% and decreased as the applied normal load was increased. It was found that the silane modification of the Kevlar fibres improved the wear resistance and tensile strength of the UHMWPE composites as well.     

Friction and wear properties of polyimide matrix composites reinforced with short basalt fibers

Short basalt fiber (BF) reinforced polyimide (PI) composites were fabricated by means of compression‐molding technique. The friction and wear properties of the resulting composites sliding against GCr15 steel were investigated on a model ring‐on‐block test rig under dry sliding conditions. The morphologies of the worn surfaces and the transfer films that formed on the counterpart steel rings were analyzed by means of scanning electron microscopy. The influence of the short BF content, load, and sliding speed on the tribological behavior of the PI composites was examined. Experimental results revealed that the low incorporation of BFs could improve the tribological behavior of the PI composites remarkably. The friction coefficient and wear rate decreased with increases in the sliding speed and load, respectively. The transfer film that formed on the counterpart surface during the friction process made contributions to reducing the friction coefficient and wear rate of the BF‐reinforced PI composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

炭纤维增强水泥基复合材料(CFRC)的电磁性能

炭纤维增强水泥基复合材料(Carbon Fiber Reinforced Cement Composites,CFRC)是新发展起来的一种电磁屏蔽材料,它是防止电磁污染的防护性功能材料之一。本文阐述了炭纤维增强水泥基复合材料的制备成型工艺;分析了炭纤维掺入量和长度、水灰比和密实成型制备工艺、炭纤维分散性、养护龄期、外加剂、炭纤维表面化学气相沉积(CVD)处理等因素对CFRC力学性能、导电性能、压敏性能及电磁性能的影响。合适的炭纤维掺入量和长度、炭纤维的均匀分散、合理的水灰比和炭纤维表面处理是影响CFRC导电性能和电磁性能的主要因素。CFRC对电磁波的屏蔽效果除利用屏蔽效能从反射电磁波角度衡量外,亦可从吸收电磁波角度利用反射率进行评价。     

The effect of high content of fly ash on the properties of glass fiber reinforced cementitious composites

The objective of this paper was to study glass fiber reinforced cementitious composites (GFRCC) with Portland cement, a high content of fly ash as matrix. The effect of fly ash content, the initial curing time, and accelerated ageing on the flexural strength of GFRCC was investigated. The suitability of the accelerated ageing method was queried by analyzing the results from SEM observation, XRD analysis, and deflection testing.     

Friction and wear properties of NBR/PVC composites

Acrylonitrial butadiene rubber (NBR)/Polyvinyl chloride (PVC) composites with different PVC content were prepared. The effect of PVC content on the mechanical strength and tribological properties of the NBR/PVC composites was investigated. The morphologies of the worn traces and debris of NBR/PVC composites and worn traces of mating ball were observed using a scanning electron microscope (SEM). It was found that the friction and wear of NBR/PVC was lower than that of NBR without PVC. The NBR/PVC composite with 30% PVC content showed the best synthetic mechanical and tribological properties. The inferior elastic properties and the lesser deformation under the applied load of composites with PVC resulted in hysteric force and adhesion force decrease, which leading to a lower friction and wear of NBR/PVC composites. The frictional failure unit of NBR70/PVC30 composite being smaller should be an important reason of the wear of the composite being lowest. The lubricating effect of PVC played an important role in decreasing the friction coefficient and wear of NBR/PVC composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

聚酰亚胺薄膜及纤维的探索研究

利用均苯四甲酸二酐(PMDA)、4,4'-二氨基二苯醚(4,4'-ODA)和自制三单体在强极性非质子有机溶剂N,N-二甲基乙酰胺(DMAc)中进行共缩聚反应,制得高粘度的聚酰胺酸(PAA)溶液,经涂膜、热亚胺化,得到坚韧透明的聚酰亚胺(PI)薄膜,其具有较好的拉伸断裂强度和合适的伸长率;同时将得到的PAA溶液进行湿法纺丝,制成PAA纤维,采用热亚胺化和高温拉伸的方法制得PI纤维,其断裂强度能达到3.67cN/dtex。     

Effect of surface treatment on the tribological performance of carbon fiber reinforced thermoplastic polyimide composites

The effect of rare earth solution (RES) surface treatment of carbon fibers (CFs) on the tensile strength and tribological properties of CF‐reinforced polyimide (CF/PI) composite was investigated. Experimental results revealed that the tensile strength of RES‐treated CFs reinforced PI composite was improved by about 19% compared with that of untreated composite, while 7% improvement was achieved by air oxidation. Compared with the untreated and air‐oxidated CF/PI composite, the RES‐treated composite had the lowest friction coefficient and specific wear rate under given applied load and reciprocating sliding frequency. RES treatment effectively improved the interfacial adhesion between CFs and PI. The strong interfacial adhesion of the composite made CFs not easy to detach from the PI matrix and prevented the rubbing‐off of PI, and accordingly improved the friction and wear properties of the composite. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Enhanced thermoelectric properties of carbon fiber reinforced cement composites

Thermoelectric properties of carbon fiber reinforced cement composites (CFRCs) have attracted relevant interest in recent years, due to their fascinating ability for harvesting ambient energy in urban areas and roads, and to the widespread use of cement-based materials in modern society. The enhanced effect of the thin pyrolytic carbon layer (formed at the carbon fiber/cement interface) on transport and thermoelectric properties of CFRCs has been studied. It has been demonstrated that it can enhance the electrical conduction and Seebeck coefficient of CFRCs greatly, resulting in higher power factor 2.08 µW m⁻¹ K⁻² and higher thermoelectric figure of merit 3.11×10⁻³, compared to those reported in the literature and comparable to oxide thermoelectric materials. All CFRCs with pyrolytic carbon layer, exhibit typical semiconductor behavior with activation energy of electrical conduction of 0.228-0.407 eV together with a high Seebeck coefficient. The calculation through Mott’s formula indicates the charge carrier density of CFRCs (10¹⁴–10¹⁶ cm⁻³) to be much smaller than that of typical thermoelectric materials and to increase with the carbon layer thickness. CFRCs thermal conductivity is dominated by phonon thermal conductivity, which is kept at a low level by high density of micro/nano-sized defects in the cement matrix that scatter phonons and shorten their mean free path. The appropriate carrier density and mobility induced by the amorphous structure of pyrolytic carbon is primarily responsible for the high thermoelectric figure of merit.     

碳纤维增强氯丁橡胶复合材料的制备及性能

用碳纤维（CF）作增强相、氯丁橡胶（CR）作基相及硅烷偶联剂作相容剂,制备了CF/CR复合材料,考察了CF用量、硅烷偶联剂的种类及用量、硫化条件对复合材料热老化前后性能的影响,并用扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）仪对其结构进行了表征。结果表明,制备CF/CR复合材料的最佳配方为:CR 100份,CF 12份,KH 550 2.5份;最佳硫化条件为:温度175℃,压力10 MPa,时间30 min。SEM和FTIR分析表明,KH 550处理的CF比未处理及用Si 69处理的CF与CR的相容性更好。