Influence of lubricant filling on the dry sliding wear behaviors of hybrid PTFE/Nomex fabric composite

To improve the antiwear property and load carrying capacity of hybrid PTFE/Nomex fabric/phenolic composites, graphene and graphene oxide (GO) had been synthesized and were employed as fillers, together with graphite. Sliding wear tests show that the wear rates of filler-reinforced PTFE/Nomex fabric composites were reduced greatly when compared to unfilled fabric composite. Besides, it was found that the 2 wt% GO filled PTFE/Nomex fabric composites exhibited the optimal tribological properties. It was proposed that the self-lubrication of GO, the favorable interface stability of the composite, and the uniform transfer film on the counterpart pin contributed together to the reinforced tribological property of GO filled PTFE/Nomex fabric composite. We also investigated the influence of filler content, applied load, sliding speed, and tensile and bonding strength on the tribological properties of PTFE/Nomex fabric composites.     

Friction and wear of Synfluo 180XF wax and nano-Al2O3 filled Nomex fabric composites

Nomex fabric composites filled with the particulates of Synfluo 180XF wax (SFW) and nano-Al₂O₃ was prepared by dip-coating of Nomex fabric in a phenolic resin containing particulates to be incorporated and the successive curing. The friction and wear performance of the pure and filled Nomex fabric composites sliding against AISI-1045 steel in a pin-on-disk configuration were evaluated on a Xuanwu-III high temperature friction and wear tester. The microstructure of the composites, and the morphologies of the worn surfaces and the morphologies of counterpart steel pins were analyzed by means of scanning electron microscopy. And the elemental plane distribution of Al on the cross-section of the Nomex fabric composites filled with nano-Al₂O₃ was analyzed with an energy dispersive X-ray analyzer (EDAX). The results showed that the addition of Synfluo 180XF wax in composites have the potential to increase wear resistance and friction reduction of Nomex fabric composites, and the addition of the nano-Al₂O₃ with the optimum mass fraction in composites can improve the anti-wear ability of the composites. Besides the self-properties of the filler, the character of the microstructure of the Nomex fabric composites filled with different particles, coupled with the character of the transfer film, largely accounts for the improved anti-wear and friction-reducing abilities of the filled Nomex fabric composites as compared with the unfilled one.     

Tribological and mechanical properties of the composites made of carbon fabrics modified with various methods

Carbon fabric (CF) was modified with strong HNO₃ etching, plasma bombardment, and anodic oxidation, respectively. The modified carbon fabric was then used to prepare carbon fabric composites (CFC) by dip-coating in a phenolic resin and the relative mass content of carbon fabric in the carbon fabric composites is 65%. The friction and wear behaviors of the carbon fabric composites were evaluated with a Xuanwu-III high temperature friction and wear tester, and their mechanical properties were evaluated on a Shimadzu™ universal materials testing machine, respectively. The changes in the chemical compositions of the unmodified and modified carbon fabrics were analyzed by means of X-ray photoelectron spectroscopy. The morphologies of the worn surfaces of the unmodified and modified carbon fabric composites were analyzed by means of scanning electron microscopy. It was found that the friction-reduction and anti-wear properties of the carbon fabric composites were improved by anodic oxidation, plasma bombardment, and strong HNO₃ etching, so were the mechanical properties and load-carrying capacity. The composite made of the carbon fabric modified with anodic oxidation showed the best tribological and mechanical properties, and the one made of the carbon fabric etched with HNO₃ had the poorest tribological and mechanical properties among the three kinds of the tested composites. The active groups were produced during the oxidation process, which contributed to strengthen the bonding strength between the carbon fabric and the adhesive and hence to improve the tribological and mechanical properties of the composites made of the modified carbon fabric. The friction and wear properties of the carbon fabric composites were closely dependent on the environmental temperature. Namely, the wear rates of the composites at elevated temperature above 180 °C were much larger than that below 180 °C, which was attributed to the degradation and decomposition of the adhesive resin at excessively elevated temperature. Moreover, the composite made of the carbon fabric modified with anodic oxidation had better thermal stability than the one made of the unmodified carbon fabrics.     

Influence of Surface Modification on Tribo-Performance of Hybrid Glass/PTFE Fabric Composite with Phenolic Resin Binder

The fabric/phenolic composites with the pure and silanized hybrid glass/PTFE fabric were prepared by dip-coating of the hybrid glass/PTFE fabrics in a phenolic resin. The friction and wear performances of the resulting fabric composites were evaluated using pin-on-disc wear tester. The composition change of the glass fabric in hybrid glass/PTFE fabric after silanization was analyzed by FTIR spectroscopy. The morphologies of the composite structures and the worn surfaces of the composites were analyzed by means of scanning electron microscopy (SEM). The results show that the fabric/phenolic composite with the β-aminoethyltrimethoxylsilane silanized hybrid glass/PTFE fabric can obtain the highest load-carrying capacity and the best wear-resistance, followed by the composite with γ-glycidoxypropyltrimethoxysilane silanized hybrid glass/PTFE fabric. Chemical reactions have achieved as the hybrid glass/PTFE fabric was silanized with β-aminoethyltrimethoxyl silane or γ-glycidoxypropyltrimethoxy silane, which contribute to strengthen the bonding strength between the fabric and the adhesive and hence to improve the tribological properties of the hybrid glass/PTFE fabric composites.     

Study on the friction and wear behavior of basalt fabric composites filled with graphite and nano-SiO2

To improve the friction and wear behavior of basalt fabric reinforced phenolic composites, single graphite or nano-SiO₂ and both of them were incorporated. The tribological properties of the resulting composites under different sliding conditions were investigated systematically on a model ring-on-block test rig. The friction and wear mechanisms of the composites were studied through analyzing the worn surfaces and transfer films by a scanning electron microscopy (SEM). Experimental results showed that graphite (Gr) was more beneficial than nano-SiO₂ in improving the tribological properties of basalt fabric composites (BFC) when they were singly incorporated. It is well worth noting that the friction and wear behavior of the filled composites was improved further when nano-SiO₂ and graphite were added together, indicating that there was a synergistic effect between them. Tribological tests under different sliding conditions revealed that the BFC/Gr/SiO₂ composites seemed to be more suitable for tribological applications under higher sliding speed and load.     

Friction and wear studies of polyimide composites filled with short carbon fibers and graphite and micro SiO2

Polyimide (PI) composites filled with short carbon fibers (SCFs), micro SiO₂, and graphite (Gr) particles were prepared by means of hot press 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. Experimental results revealed that single incorporation of graphite and SCF significantly improve the tribological properties of the PI composites, but micro SiO₂ was harmful to the improvement of the friction and wear behavior of the PI composite. It is found that a combinative addition of Gr, SCF and micro SiO₂ was the most effective in improving the friction-reducing and anti-wear abilities of the PI composites. Research results also show that the filled PI composites exhibited better tribological properties under higher PV-product.     

Study on the synergistic effect of carbon fiber and graphite and nanoparticle on the friction and wear behavior of polyimide composites

In this paper, the effect of short carbon fiber (SCF), graphite (Gr) and nano-Si₃N₄ on the friction and wear behavior of polyimide (PI) composites were studied using a block-on-ring arrangement. Experimental results revealed that single incorporation of SCF and Gr can improve the friction-reducing and anti-wear abilities of the PI composites significantly. However, nano-Si₃N₄ deteriorated the wear resistance of the PI composite drastically as single filler. A synergistic effect was found for the combination of nano-Si₃N₄ and SCF and Gr, which lead to the best tribological properties. It also can be found that the filled PI composites exhibited better tribological properties under higher PV product (the product of load and sliding speed). Moreover, the filled PI composites showed better tribological properties under oil lubrication and worse tribological properties under water lubrication compared with that under dry sliding condition.     

纳米和微米Fe2O3颗粒填充UHMWPE基复合材料的摩擦学性能研究

利用MM 200型摩擦磨损试验机,较系统地考察了纳米Fe2O3填充的UHMWPE基复合材料的摩擦学性能,并与微米Fe2O3填充的复合材料作了对比研究。结果显示纳米Fe2O3粉体增强UHMWPE复合材料比微米Fe2O3粉体增强UHMWPE具有更好的减磨和抗磨性,文中对纳米和微米Fe2O3颗粒增强UHMWPE的磨损机理进行了分析。     

空心微珠-碳纤维共混改性聚酰亚胺复合材料的摩擦学性能

通过模压成型制备了碳纤维与空心微珠共混改性的聚酰亚胺复合材料, 采用MRH-3型摩擦磨损试验机研究了空心微珠含量、滑动速度及载荷对复合材料摩擦学性能的影响, 并对其磨损形貌及机制进行了分析。结果表明: 空心微珠-碳纤维/聚酰亚胺复合材料摩擦学性能优于其单独填充的聚酰亚胺基复合材料; 空心微珠含量对共混改性的复合材料摩擦系数影响不大, 但其磨损率随着空心微珠含量的增加先减小后增大; 15%空心微珠-10%碳纤维(质量分数)共混增强的复合材料的减摩耐磨性能最佳; 随着滑动速度提高, 空心微珠-碳纤维/聚酰亚胺复合材料的摩擦系数下降, 磨损率增大; 空心微珠-碳纤维/聚酰亚胺复合材料摩擦系数随着载荷增加先下降后上升, 而磨损率则随着载荷增加而增大; 空心微珠-碳纤维/聚酰亚胺的主要磨损机制在较低载荷时为磨粒磨损, 在较高载荷时为粘着磨损和磨粒磨损。     

等离子处理碳纤维织物复合材料的摩擦学性能

将碳纤维织物浸渍-涂层酚醛-缩醛粘结剂树脂,加压固化后制备出碳纤维织物复合材料.分析了摩擦磨损表面和经等离子体处理后碳纤维织物化学组成的变化,研究了摩擦磨损性能、拉伸性能和粘结性能.结果表明,碳纤维织物的磨损分为严重磨损和稳定磨损两个阶段,其中严重磨损阶段的磨损量占了总磨损量的87%.经过等离子体处理后,在碳纤维织物的表面产生了许多活性基团如羰基、羧基、酯基,表面活性元素的含量明显增多;碳纤维织物的浸润性增大,提高了其与粘结剂的结合强度和结合量,增强了织物纤维束间的结合力;固化后与粘结剂构成很好的整体材料,增强了纤维束抗变形和抗断裂能力,使载荷和摩擦力可以平均的分配在纤维上,避免应力集中,从而提高了碳纤维织物复合材料的摩擦学性能和力学性能.     

Effects of nano-sized and micro-sized carbon fibers on the interlaminar shear strength and tribological properties of high strength glass fabric/phenolic laminate in water environment

In order to clarify the effects of carbon fiber size on the properties of carbon fiber/high strength glass fabric (HSGF)/phenolic laminate, two kinds of laminates modified by nano-sized carbon fibers (CNFs) and micro-sized carbon fibers (CMFs), were respectively fabricated. The interlaminar shear strength (ILSS) and tribological properties of HSGF/phenolic laminates modified by CNFs and CMFs in water environment were comparatively investigated. Results showed that CNFs at proper contents ranging from 1.0% to 3.0% can enhance ILSS of HSGF/phenolic laminate, while CMFs deteriorated the ILSS. After water immersion, ILSS of the laminates modified by CNFs at 1.0–3.0% were just slightly decreased; however, those of the laminates modified by CMFs suffered larger drop. On the other hand, however, CMFs were more effective than CNFs in improving the wear resistance of HSGF/phenolic laminate in water.     

高填充Al2O3-聚丙烯酰胺复合材料的摩擦学特性

利用凝胶注模方法可以制备出高填充含量的Al2O3-聚丙烯酰胺复合材料。考察了PTFE对高填充聚合物复合材料摩擦学性能的影响，并对复合材料的磨损机理进行了探讨。研究表明．在适当高的填充条件下．复合材料的力学性能和摩擦磨损性能可以得到一定的改善，PTFE的填充将降低Al2O3-聚丙烯酰胺复合材料的力学性能，并使材料的摩擦系数有所增大；但是复合材料的耐磨特性可以得到显著改善。高填充含量的PTFE-Al2O3聚丙烯酰胺复合材料表现出了摩阻材料特性。Al2O3-聚丙烯酰胺复合材料的磨损主要表现为磨粒磨损特征。     

PTFE及纳米粒子改性环氧树脂基聚酯织物增强复合材料的拉伸及摩擦学性能

为了研究填料(纳米粒子和PTFE)对聚酯织物增强复合材料的拉伸及摩擦学性能(轴向及偏轴方向)的影响,使用手糊成型的方法制备了四种环氧树脂基聚酯织物增强复合材料.根据拉伸应力-应变曲线和断口形貌图讨论了拉伸断裂机理.使用环-块式结构的Amsler摩擦磨损试验机测试织物增强复合材料的摩擦学性能.结果表明:对于纯环氧树脂/织物增强复合材料来说,聚酯织物在整个织物增强复合材料的拉伸和摩擦磨损测试中起到了主要的抗拉和耐磨作用;但当在环氧树脂中加入填料后,环氧树脂基体在抗拉和耐磨性方面起到了越来越重要的作用.拉伸性能的提高是由于纤维-基体间界面的改善;由于填料具有优异的摩擦磨损性能,从而使织物增强复合材料的摩擦学性能得到了提高;并且纳米粒子和PTFE对于织物复合材料性能的提高起到了协同的作用.织物增强复合材料偏轴方向的拉伸性能和摩擦学性能与其在轴向的拉伸性能和摩擦学性能不同.     

Enhancement on interlaminar shear strength and tribological properties in water of ultra high molecular weight polyethylene/glass fabric/phenolic laminate composite by surface modification of fillers

The ternary laminate composite of ultra high molecular weight polyethylene (UHMWPE)/high strength glass fabric (S-glass fabric)/phenolic resin was prepared, in which UHMWPE microparticles were etched by chromic acid and S-glass fabrics were treated by silane coupling agent. The interlaminar shear strength (ILSS) and tribological properties of the composite in water environment were investigated, in comparison with those of the composite without any treatments on fillers and the composite with single treatment on UHMWPE. Results showed that the composite with the combined treatment exhibited the best interfacial bond, accordingly showing remarkably enhanced water repellency, ILSS and tribological properties under water lubrication. Furthermore, after experiencing 48 h water immersion, the composites with both single and combined treatment did not suffer any degradation of ILSS and water-lubricated tribological performances, showing excellent duration in water environment.     

纳米TiO2与炭纤维协同填充PTFE复合材料的摩擦磨损性能

考察了不同含量的纳米二氧化钛对炭纤维/聚四氟乙烯复合材料摩擦磨损性能的影响,采用扫描电子显微镜、光学显微镜分析了磨损面、磨屑及对偶面转移膜形貌,并探讨了其磨损机理。结果表明,纳米TiO2与炭纤维能够很好地协同增强聚四氟乙烯,改变磨屑形成机理,有利于形成均匀致密的转移膜,明显提高CF/PTFE复合材料的耐磨性。当纳米TiO2含量为5%时,10?/PTFE复合材料表现出最佳的耐磨性,耐磨性又提高了2.77倍,而磨屑尺寸只有未加时的1/20。     

Optimization of tribological parameters in abrasive wear mode of carbon-epoxy hybrid composites

Abrasive wear performance of fabric reinforced composites filled with functional fillers is influenced by the properties of the constituents. This work is focused on identifying the factors such as filler type, filler loading, grit size of SiC paper, normal applied load and sliding distance on two-body abrasive wear behaviour of the hybrid composites. Abrasive wear tests were carried on carbon fabric reinforced epoxy composite (C-E) filled with filler alumina (Al₂O₃) and molybdenum disulphide (MoS₂) separately in different proportions, using pin-on-disc apparatus. The experiments were planned according to Taguchi L18 orthogonal array by considering five factors, one at two levels and the remaining at three levels, affecting the abrasion process. Grey relational analysis (GRA) was employed to optimize the tribological parameters having multiple-response. Analysis of variance (ANOVA) was employed to determine the significance of factors influencing wear. Also, the comparative specific wear rates of all the composites under dry sliding and two-body abrasive wear were discussed. The analysis showed that the filler loading, grit size and filler type are the most significant factors in controlling the specific wear rate of the C-E composite. Optimal combination of the process parameters for multi performance characteristics of the composite under study is the set with filler type as MoS₂, filler loading of 10 wt.%, grit size 320, load of 15 N and sliding distance of 30 m. Further, the optimal parameter setting for minimum specific wear rate, coefficient of friction and maximum hardness were corroborated with the help of scanning electron micrographs.     

Synergistic effects of TiC and graphene on the microstructure and tribological properties of Al2024 matrix composites

Al matrix composites have attracted significant attention of researchers in recent years due to their lightweight, excellent mechanical and tribological properties. In this study, an Al2024 matrix hybrid composite (AMHC) reinforced with both TiC nanoparticles and graphene nanoplatelets (GNPs) was produced via a route of powder metallurgy. And its microstructure, microhardness and tribological properties are compared with those of unreinforced Al2024 alloy matrix and Al2024 matrix composites reinforced with either only TiC or GNPs. It was found that the distribution of Al₂Cu, TiC nanoparticles and GNPs in the matrix and the wear resistance are significantly improved when introducing both TiC nanoparticles and the GNPs. The wear mechanisms change from the adhesion-dominant wear for Al2024 and the other singly reinforced composites into abrasive-dominant wear for the hybrid composite. The significantly improved wear resistance of the AMHC is attributed to the synergistic effects of reinforcing and self-lubricating of the TiC and GNPs.     

Friction and wear of epoxy/TiO2 nanocomposites: Influence of additional short carbon fibers, Aramid and PTFE particles

An epoxy-based nanocomposite containing graphite powder (7 vol%) and nano-scale TiO₂ (4 vol%) was developed for tribological evaluation. A series of composites containing additional fillers such as short carbon fibers (SCF), Aramid and polytetrafluoroethylene (PTFE) particles was developed and evaluated in adhesive and low amplitude oscillating wear modes. The incorporation of SCF and Aramid particles resulted in a remarkable improvement in the sliding wear resistance. However, SCF impaired the low amplitude oscillating wear resistance. The further addition of PTFE to the SCF filled nanocomposites reduced the friction and wear under both wear conditions. However, an adverse effect of PTFE was found for the Aramid particles filled nanocomposites. Under sliding conditions, the lowest wear rate and coefficient of friction showed the 2–4 vol% PTFE filled SCF nanocomposite. Aramid particles containing nanocomposites (without PTFE) exhibited the best wear and friction behavior under low amplitude oscillating wear conditions among the selected composites. The wear mechanisms were studied by scanning electron microscopy.     

Tribological behaviour and wear of carbon nanotubes grafted on carbon fibres

Carbon nanotubes (CNTs) grafted on fibres are widely used to reinforce composites in order to improve their mechanical properties. This study concerned the tribological properties of CNTs grafted on carbon fibres by the flame method. The aim of this study was to determine whether CNTs on fibres suffer damage under stress, similar to those applied during composite manufacturing, which can damage composite properties, particularly fibre/matrix adhesion. For this purpose, reciprocating friction tests were performed to examine the resistance of CNTs and highlight a wear mechanism. The results showed that the presence of CNTs increased the coefficient of friction in the first friction cycles and then decreased it to close to the COF of the fibre without CNTs. The wear mechanism showed that after a small number of friction cycles, the CNTs were flattened out and formed a transfer film.     

莫来石与碳纤维协同填充的聚四氟乙烯基复合材料及其摩擦学性能

为了提高聚四氟乙烯（PTFE）的摩擦学性能,采用机械混匀、带温预压及烧结等工艺制备了莫来石和碳纤维填充的PTFE基复合材料,并通过FTIR、XRD、万能材料试验机、洛氏硬度计、DSC及热机械分析分别表征了PTFE基复合材料的显微结构、力学性能和热学性能;然后,使用MRH-3 型高速环块磨损试验机测定了复合材料的摩擦系数和磨损率,通过自制的硅油砂浆磨损装置测定了复合材料在不同温度下的耐砂浆磨损性能;最后,借助3D测量激光显微镜研究了复合材料摩擦面形貌,并分析了摩擦磨损机制。结果表明:莫来石和碳纤维在PTFE体系中起到填充增强作用,20wt%莫来石-10wt%碳纤维/PTFE复合材料的弹性模量由364 MPa增加至874 MPa;20wt%莫来石-10wt%碳纤维/PTFE复合材料的干摩擦系数较大,但其磨损率与纯PTFE相比降低了3个数量级以上,且此复合材料在水摩擦条件下仍能保持较好的摩擦系数和磨损率,摩擦系数为0.157,磨损率为7.40×10-6 mm3·N-1·m-1;此外,20wt%莫来石-10wt%碳纤维/PTFE复合材料在较高温度下仍能表现出良好的耐砂浆磨损性能。所得结论表明改性得到的PTFE 基复合材料的摩擦学性能显著提高,复合材料可用于有杆抽油井防偏磨。