Effect of Aramid Pulp and Lapinas Fiber on the Friction and Wear Behavior of NBR Powder–Modified Phenolic Resin Composite

Short fiber reinforcement plays a definite role in governing the performance of a composite through the improvement of different material properties. The present investigation deals with the effect of aramid pulp and lapinas fiber on the friction and wear characteristics of a composite made from phenolic resin modified by powdered acrylonitrile butadiene rubber (NBR) on a pin-on-disc tribometer. Four composites, containing 10, 20, 30, and 40 wt% of aramid pulp with respect to phenolic resin content, were prepared. Another four composites, containing 50, 100, 200, and 300 wt% of lapinas fiber with respect to phenolic resin content, were also made. It was found that the two different fibers have distinctly different contributions to the friction and wear properties of the composites. It was also found that the incorporation of aramid pulp enhances friction stability of the composites much better than that of lapinas fiber. The change in surface morphology of these composites was studied by scanning electron microscopy (SEM) before and after the friction test. SEM images of friction samples containing aramid pulp corroborated the occurrence of wear through an adhesive wear mechanism, whereas the lapinas fiber–containing composites showed an abrasive wear mechanism.     

Sliding wear performance of nano-SiO2/short carbon fiber/epoxy hybrid composites

In the present work, epoxy based composites filled with hybrid nano-SiO₂ particles and short pitch based carbon fiber were prepared. Copolymer of styrene and maleic anhydride was grafted onto the nanoparticles prior to the compounding so that the nanoparticles can be covalently connected to the composites’ matrix through the reaction between anhydride and epoxide groups during curing. Consequently, the nano-SiO₂/matrix interfacial interaction was enhanced. By evaluating sliding wear properties of the composites as a function of the components concentrations, positive synergetic effect was found. That is, both wear rate and friction coefficient of the hybrid composites were significantly lower than those of the composites containing individual nano-SiO₂ or short carbon fiber. The composite with 4 wt.% nano-SiO₂ and 6 wt.% carbon fiber offered the greatest improvement of the tribological performance. Compared to the results of hybrid composites reported so far, the above composite is characterized by relatively lower filler content, which would facilitate processing in practice. Increased surface hardness, lubricating effect of the sheet-like wear debris reinforced by nano-SiO₂ and rapidly formed transfer film were believed to be the key issues accounting for the remarkable wear resisting and friction reducing behaviors.     

Tribological behaviour of polymeric coatings. Part I. Aramid particle‐reinforced epoxy nanocomposite systems

An epoxy‐based nanocomposite containing a low concentration of nanometric TiO₂ (4 vol. %), graphite powder (7.21 vol. %), and 2–14 vol. % aramid particles was developed as a coating material. The mechanical and tribological performance of the composites was investigated. The epoxy filled only with TiO₂ possessed significantly improved impact strength and flexural properties, whereas the further incorporation of graphite and aramid particles had a deleterious effect on most of the mechanical properties, except the modulus. The tribological behaviour of the composites was tested in sliding and fretting modes. Under sliding conditions, the addition of nanometric TiO₂ alone significantly improved the wear resistance and decreased the coefficient of friction compared to the neat epoxy. The sliding wear and friction behaviour was further enhanced with the incorporation of graphite and aramid particles. Contrary to the sliding wear behaviour, the fretting wear and friction behaviour was worse for the epoxy filled only with TiO₂, but was significantly enhanced by the incorporation of graphite and aramid particles. The optimum aramid particle content for sliding and fretting wear of the epoxy‐based nanocomposite was determined as 10 vol. %.     

Tribological Behavior of Particles and Fiber-Reinforced Hybrid Nanocomposites

This article discusses the mechanical performance of alumina nanoparticles and randomly distributed short glass/carbon fiber-reinforced hybrid composites through microhardness and wear test. The open mold casting method was adapted to prepare the test coupons. The wear and friction behavior of composites sliding against hardened ground EN 32 steel in a pin-on-disc configuration is evaluated on a wear and friction tester. The microhardness properties of the neat epoxy, alumina nanoparticles, and alumina nanoparticle–embedded glass/carbon fiber–reinforced hybrid composites were determined. The morphology of the worn composites was analyzed with a scanning electron microscope. It was found that the particles as fillers contributed significantly to improve the mechanical properties and wear resistance of the polymer composites. This is because the fillers contributed to enhance the bonding strength between the fiber and the epoxy resin. Moreover, the wear and friction resistance of the glass/carbon fiber composites was increased by increasing the filler weight in the composite materials.     

Dry sliding wear characteristics of glass–epoxy composite filled with silicon carbide and graphite particles

The dry sliding wear characteristics of a glass–epoxy (G–E) composite, filled with both silicon carbide (SiC_p) and graphite (Gr), were studied using a pin-on-disc test apparatus. The specific wear rate was determined as a function of sliding velocity, applied load and sliding distance. The laminates were fabricated by the hand lay-up technique. The volume percentage of filler materials in the composite was varied, silicon carbide was varied from 5 to 10% whereas graphite was kept constant at 5%. The excellent wear resistance was obtained with glass–epoxy containing fillers. The transfer film formed on the counter surface was confirmed to be effective in improving the wear characteristics of filled G–E composites. The influence of applied load is more on specific wear rate compared to the other two wear parameters. The worn surfaces of composites were examined with scanning electron microscopy (SEM) to investigate the probable wear mechanisms. It was found that in the early stage of wear, the fillers contribution is significant. The process of transfer film, debris formation and fiber breakage accounts for the wear at much later stages.     

炭黑/双马来酰亚胺复合材料的性能研究

采用浇铸成型法制备了炭黑填充双马来酰亚胺(BM I-BA)复合材料,研究了炭黑的填充量对复合材料力学性能和摩擦学性能的影响。在M-200型磨损机上测试该复合材料的摩擦学性能,利用扫描电镜(SEM)观察了摩擦副的表面形貌。结果表明:炭黑能够有效提高复合材料的力学性能和摩擦学性能。当炭黑的添加量为4.0wt%时,复合材料的综合力学性能最好;当炭黑的的添加量为6.0wt%时,复合材料的耐磨性能最好。SEM显示复合材料主要是粘着磨损,能在对磨环上形成薄而连续均匀的转移膜,而BM-BA树脂主要发生的是疲劳磨损,并伴有塑性变形。     

Mechanical and Tribological Properties of Spark Plasma–Sintered Titanium Composites Filled with Different Al-Cr-Fe Quasicrystal Contents

A new type of Ti composite filled with Al-Cr-Fe quasicrystals (QCs) was developed via a spark plasma sintering process. The mechanical and tribological properties of the Ti/QC composites were systematically investigated. It was found that the hardness of the Ti/QC composites significantly increased with increased QC content due to the higher hardness of incorporated QCs than that of the Ti matrix. The tribological results clearly showed that the wear of the Ti/QC composites apparently decreased with increased QC content to 20 wt% as a result of the increased wear resistance of the composites. An excessive loading of 30 wt% QCs resulted in the decreased wear resistance of the Ti/QC composites. It could be concluded that the incorporation of QCs significantly improved the mechanical and tribological properties of the Ti/QC composites with an optimized QC content of 20 wt%.     

石墨填充聚醚酰亚胺摩擦学性能分析

在M-200摩擦试验机上进行不同含量石墨填充PEI基复合材料的摩擦磨损试验,利用扫描电子显微镜分析了断口和磨损表面的显微结构,并分析了磨损机制。考察了表面硬度随含量填充量的变化规律。试验结果表明:石墨在复合材料基体中呈片状结构,磨损过程中易形成转移膜,从而改善了摩擦磨损情况,其中填充质量分数10%石墨的PEI基复合材料摩擦因数最低,填充30%石墨的复合材料磨损率最低,材料表面硬度随着填充石墨含量的增加而降低,石墨填充量在5%～30%之间表面硬度下降平缓,当填充量超过30%时,材料表面硬度下降剧烈。     

Friction and wear properties of Kevlar pulp reinforced epoxy composites under dry sliding condition

In this work, the friction and wear properties of Kevlar pulp reinforced epoxy composites against GCr15 steel under dry sliding condition were evaluated on a reciprocating ball-on-block UMT-2MT tribometer. The effects of Kevlar pulp content on tribological properties of the composites were investigated. The worn surface morphologies of neat epoxy and its composites were examined by scanning electron microscopy (SEM) and the wear mechanisms discussed. The results show that the incorporation of Kevlar pulp into epoxy contributed to improve the friction and wear behavior considerably. The maximum wear reduction was obtained when the content of Kevlar pulp is 40 vol%. The friction coefficient of epoxy and its composites increased with load while increase in the sliding frequency induced a reverse effect. Fatigue wear and scuffing were notable for the neat epoxy. The fatigue cracks were greatly abated when the filler content was 40 vol%. The wear grooves appeared on the worn surface at higher filler content.     

Investigations on the influence of graphite filler on dry sliding wear and abrasive wear behaviour of carbon fabric reinforced epoxy composites

In this experimental study, the dry sliding wear and two-body abrasive wear behaviour of graphite filled carbon fabric reinforced epoxy composites were investigated. Carbon fabric reinforced epoxy composite was used as a reference material. Sliding wear experiments were conducted using a pin-on-disc wear tester under dry contact condition. Mass loss was determined as a function of sliding velocity for loads of 25, 50, 75, and 100 N at a constant sliding distance of 6000 m. Two-body abrasive wear experiments were performed under multi-pass condition using silicon carbide (SiC) of 150 and 320 grit abrasive papers. The effects of abrading distance and different loads have been studied. Abrasive wear volume and specific wear rate as a function of applied normal load and abrading distance were also determined.The results show that in dry sliding wear situations, for increased load and sliding velocity, higher wear loss was recorded. The excellent wear characteristics were obtained with carbon-epoxy containing graphite as filler. Especially, 10 wt.% of graphite in carbon-epoxy gave a low wear rate. A graphite surface film formed on the counterface was confirmed to be effective in improving the wear characteristics of graphite filled carbon-epoxy composites. In case of two-body abrasive wear, the wear volume increases with increasing load/abrading distance. Experimental results showed the type of counterface (hardened steel disc and SiC paper) material greatly influences the wear behaviour of the composites. Wear mechanisms of the composites were investigated using scanning electron microscopy. Wear of carbon-epoxy composite was found to be mainly due to a microcracking and fiber fracture mechanisms. It was found that the microcracking mechanism had been caused by progressive surface damage. Further, it was also noticed that carbon-epoxy composite wear is reduced to a greater extent by addition of the graphite filler, in which wear was dominated by microplowing/microcutting mechanisms instead of microcracking.     

A correlation between the tribological and mechanical properties of short carbon fibers reinforced PEEK materials with different fiber orientations

In this work the effect of fiber orientation on the mechanical and tribological properties of SCF (short carbon fibers)/PTFE (poly-tetra-fluor-ethylene)/graphite filled PEEK (poly-ether-ether-keton) composites was studied. The composites were manufactured by using injection molding technique. Mechanical and tribological experiments were conducted to measure the compression modulus, compression strength and wear resistance. A correlation of the tribological and mechanical properties considering different fiber orientations was studied. Additionally to the fiber orientation influence, the wear resistance under low and high pressures was examined. The results analyses, based on scratch experiments and scanning electron microscope (SEM) inspections explain how the fiber orientation influences the mechanical performance and the tribological properties of the considered materials.     

碳管分散程度对环氧树脂复合材料的摩擦磨损性能影响

采用浇铸法,制备多壁碳纳米管(MWNTs)/环氧树脂(EP)复合材料,利用M-200摩擦磨损试验机研究了MWNTs含量、分散时间及方式对环氧复合材料摩擦磨损性能影响,通过SEM、TEM分析试样磨损形貌表面、MWNTs分散程度。结果表明:碳纳米管添加量1.5%(质量分数)时,MWNTs/EP复合材料比环氧树脂摩擦因数降低17.8%,磨耗率降低91.7%;加入碳纳米管降低了复合材料粘着磨损与疲劳剥落;延长超声波时间及采用高功率超声波仪器能够有效提高碳纳米管分散程度,提高复合材料摩擦磨损性能。     

共沉淀法制备纳米Al2O3强化铜基复合材料微动磨损研究

采用共沉淀法制备了纳米Al2O3／Cu基复合材料,研究了不同Al2O3含量对铜基复合材料摩擦磨损性能的影响。结果表明,复合材料的耐磨性能明显优于基体材料,随着Al2O3含量的增加,复合材料的耐磨性能先升高后下降,以Al2O3含量2％为最佳,相对耐磨性为3．13。纯铜的磨损表现为粘着磨损,而复合材料则逐渐转变为磨粒磨损,并伴有一定的氧化磨损。     

Friction and Wear of Epoxy Composites Containing Surface Modified SiC Nanoparticles

The authors of the present paper evaluated the sliding wear behaviors of epoxy and its composites filled with untreated and treated SiC nanoparticles. The experimental results indicate that the nanoparticles pretreated by graft polymerization of polyacrylamide effectively improved the overall performance of the matrix epoxy. In comparison with the untreated SiC nanoparticles, the grafted SiC nanoparticles led to more significant reduction in frictional coefficient and wear rate of epoxy. Even under high contact pressure, the composites with grafted SiC nanoparticles possessed the highest wear resistance. The strong interfacial bonding between the grafted SiC nanoparticles and the matrix should account for the properties enhancement. Accordingly, a feasible way of efficiently applying SiC nanoparticles to the preparation of wear resisting nanocomposites has been developed.     

Effect of surface treatment on the mechanical and tribological performance of Kevlar pulp reinforced epoxy composites

Solutions of rare earth modifier (RES) and epoxy chloropropane (ECP) grafting modification method were used for the surface treatment of Kevlar pulp. The surface characteristics of untreated and treated Kevlar pulp were characterized by Fourier transform infrared (FT-IR) spectroscope. The bend strength and block-on-ring wear behavior of Kevlar pulp/epoxy composites were comparatively investigated. The worn surfaces of the composites were examined by scanning electron microscope (SEM). The results show that surface treatment can effectively improve the interfacial adhesion between Kevlar fiber and epoxy matrix. Thus, the bend strength and wear resistance were significantly improved. The RES surface treatment is superior to ECP grafting treatment in promoting interfacial adhesion between Kevlar fiber and epoxy resin.     

Effect of Wettability Enhancement of SiC Particles on Impact Toughness and Dry Sliding Wear Behavior of Compocasted A356/20SiCp Composites

In this study, the effect of wettability improvement of SiCp on the impact and sliding wear behavior of A356/20 wt% SiCp composites produced by a compocasting technique has been investigated. The result showed an increase of incorporation and uniform distribution of SiCp in the A356 matrix by elimination of SiCp segregation. Desired bonding between SiCp and the aluminum matrix due to improved wettability resulted in enhanced properties in terms of improved impact toughness and wear resistance. This improvement was also associated with partial refinement of coarse eutectic silicon due to increased incorporation and distribution of SiCp reinforcements. The highest enhancement was obtained when 1% Mg was added into the melt in addition to pretreated SiCp. The impact toughness value increased by 10 and 26% and the wear rate decreased by 5 and 30% when the SiC was treated and when Mg was added, respectively, compared to as-received SiCp. The impact fracture surfaces showed fewer decohered and well-bonded SiC particles in A356–(SiC-treated-Mg) composite. The highest wear resistance of A356/SiCp composites was achieved by A356–(SiC-treated-Mg) composite for applied loads of 10 and 20 N compared to other fabricated composites. The worn surface revealed mild abrasion and adhesion wear mechanisms.     

Tribological Properties of Organic Functionalized ZrB<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/Epoxy Composites

The tribological behaviors of epoxy composites filled with organic functionalized ZrB₂–Al₂O₃ were environmentally investigated and compared with those with as-received fillers under both dry and oil sliding conditions in this work. The worn surfaces and the transfer films on the counterparts were characterized by scanning electronic microscope (SEM), and the frictional temperature rising was investigated by infrared thermometer. The results demonstrated that the coefficient of friction (CoF), the wear rate, as well as the frictional temperature rise of the epoxy composites were all decreased due to the introduction of ZrB₂–Al₂O₃ fillers. And with the increase in filler content, similar variation tendencies of CoF and wear rate of epoxy composites were observed under the different sliding conditions. Besides, the organic functionalization of ZrB₂–Al₂O₃ fillers, which made the epoxy composites exhibit lower CoF and wear rate than those with as-received fillers, lowered the frictional temperature as well. In comparison, the epoxy composites filled with 5 vol% modified fillers presented better tribological properties, suggesting a stronger interfacial bonding between modified fillers and epoxy matrix. The dominant wear mechanisms of filled composites under dry and oil sliding conditions could be inferred as the combination of adhesive wear and abrasive wear and the fatigue wear, respectively, on the basis of SEM images of worn surfaces.     

MoS2、CdO及聚全氟乙丙烯填充改性聚四氟乙烯复合材料的摩擦磨损性能

用机械共混、冷压成型自由烧结的方法制备了MoS2、CdO和聚全氟乙丙烯填充聚四氟乙烯复合材料;用MM-2000型摩擦磨损试验机测试了在干摩擦条件下该复合材料的摩擦磨损性能;用扫描电镜(SEM)对磨损试样的表面形貌进行观察和分析.结果表明:未添加聚全氟乙丙烯的复合材料其摩擦磨损性能比添加的好;当CdO的体积分数为22.5%,MoS2的体积分数为7.5%时,复合材料的摩擦因数最小,抗磨性强,复合材料的摩擦磨损性能最佳.     

纳米Cu粉填充碳纤维/PTFE复合材料的摩擦磨损性能

考察纳米Cu粉含量、粒径对碳纤维/PTFE复合材料摩擦磨损性能的影响,采用扫描电子显微镜分析磨损面和对偶面转移膜形貌,并探讨其磨损机制。结果表明:纳米Cu粉能提高碳纤维/PTFE复合材料的耐磨性,在高载荷下,纳米Cu粉的增强效果更加明显;纳米Cu粉的粒径越小,复合材料的耐磨性越好;添加质量分数0.3%纳米Cu粉的碳纤维/PTFE复合材料耐磨性最优,1.4 m/s,200 N下实验条件下,其磨损率比未添加时降低了45%;SEM分析显示纳米Cu粉能在对偶面上形成平整致密的转移膜,具有显微增强作用。     

表面改性硅灰石纤维填充PTFE复合材料的摩擦学性能

用KH550硅烷偶联剂表面改性的硅灰石纤维(WF)填充PTFE,在MPX-2000型磨损试验机上研究复合材料的摩擦磨损性能,并与经典的炭纤维(CF)填充PTFE复合材料进行比较。采用SEM对磨损面和对偶面进行分析。结果表明:较高载荷(200和300 N)下复合材料摩擦因数随WF含量变化的幅度不大,较稳定地维持在较低值;细小尺寸WF填充PTFE复合材料的耐磨性能较好,在WF质量分数为10%时,复合材料的磨损量只有相同含量CF填充PT-FE复合材料的81%;细小尺寸WF填充PTFE复合材料的磨损面较为平整,存在轻微黏着磨损,其对偶面转移膜平整光滑、结构致密;而CF/PTFE复合材料磨损面存在许多裸露和碎断的CF,犁削和磨粒磨损是主要的磨损形式。