碳纤维/玻璃纤维/石墨协同改性PTFE复合材料力学性能

通过机械混合、冷压和烧结成型制备了碳纤维、玻璃纤维和石墨填充协同改性聚四氟乙烯(PTFE)复合材料。对比分析了不同样品的拉伸、冲击和压缩等力学性能。结果表明:玻纤和碳纤维使复合材料冲击强度下降;玻纤使复合材料拉伸强度下降,碳纤维则使复合材料拉伸强度稍有增强;玻纤和碳纤维均使复合材料压缩强度增加,但碳纤维的增强效果更为明显;石墨、玻纤和碳纤维协同增强PTFE复合材料的拉伸强度较高,弹性模量较大,断裂伸长率较高,抗压缩性能明显提高,且材料拉伸时呈塑性断裂,是综合力学性能较好的高性能润滑密封材料。     

On the friction and wear behavior of PTFE composite filled with rare earths treated carbon fibers under oil-lubricated condition

Carbon fibers (CF) were surface treated with air-oxidation, air-oxidation followed by rare earths (RE) treatment and RE treatment, respectively. The friction and wear properties of the polytetrafluoroethylene (PTFE) composites filled with differently surface treated carbon fibers, sliding against GCr15 steel under oil lubrication, were investigated on a reciprocating ball-on-disk UMT-2MT tribometer. The worn surfaces of the PTFE composites were examined using a scanning electron microscopy (SEM). Experimental results revealed that surface treatment of carbon fibers reduced the wear of CF-reinforced PTFE composites. Among all the treatments to carbon fibers, RE treatment was the most effective and lowest friction and wear rate of CF-reinforced PTFE composite was exhibited, owing to the effective improvement of the interfacial adhesion between the carbon fibers and PTFE matrix.     

Strength characteristics,structure and wear resistance of ptfe-commercial carbon composites

The present work is devoted to investigations of the structure, mechanical properties, and wear resistance of composites based on polytetrafluoroethylene filled by 0.3–20.0% of commercial carbon. The methods used were mechanical testing, X-ray phase analysis, scanning calorimetry, scanning electron microscopy, and triboengineering tests. The wear resistance of low-filled PTFE-based composites containing 1–5% of ultradispersed commercial carbon was found to increase sharply, by up to 500–600 times, whereas the main strength characteristics of these composites, including relative elongation at rupture and tensile strength, remained at levels close to that of pure polytetrafluoroethylene (PTFE). This effect is attributed to the active cross-linking role of ultradispersed carbon particles, which promote the formation of a transient supermolecular structure in the low-filled composites; this structure is a combination of the unfilled PTFE structure and a spherulite-like supermolecular structure.     

软碳填充PTFE复合材料摩擦磨损性能研究

以不同含量的软碳为填料制备了PTFE基复合材料,测量了其机械性能,在M-2000型摩擦磨损试验机上研究其摩擦磨损行为,并探讨了其磨损机制.结果表明:软碳能提高PTFE复合材料的硬度,软碳/PTFE复合材料的耐磨性能优于纯PTFE,当软碳质量分数为7%时其耐磨性能最好.复合材料的摩擦因数随着软碳含量的增加而增加.摩擦表面的SEM观察发现:纯PTFE的摩擦表面分布着较明显的犁削和黏着磨损的痕迹,复合材料的摩擦表面均出现犁削,随着软碳含量的增加,犁削现象减轻,这表明以软碳作为填料可有效地抑制PTFE的磨损.     

Wear Resistance of Nickel–Cobalt–Polytetrafluoroethylene Composite Electrolytic Coatings Deposited from Chloride-Containing Electrolyte

The development and implementation of novel galvanic coatings with abnormally high microhardness, wear resistance, and corrosion resistance are the focus of modern machine-building. The galvanic deposition of composite electrolytic coatings (CECs) is an efficient method of improving their properties. In this paper, a chloride-containing electrolyte has been proposed for obtaining a wear-resistant nickel–cobalt–polytetrafluoroethylene CEC. The effect exerted by electrolysis modes and electrolyte compositions on some physicomechanical properties (wear resistance and corrosion resistance) of a nickel–cobalt–polytetrafluoroethylene composite electrolytic coating deposited from chloride-containing electrolyte has been studied. The potentialities of using the deposited layer as wear- and corrosion-resistant coating.     

Tribological behaviour of PTFE modified cotton polyester composites

Abstract

An attempt on modification of tribological behaviour of cotton polyester composite was done with polytetrafluoroethylene (PTFE). PTFE modified polyester–cotton composites were developed and studied for their friction and sliding wear behaviour at different applied loads. The sliding wear tests of composites were conducted against EN-31 steel counter face. The coefficient of friction μ as well as the sliding wear rate of cotton–polyester composites reduced significantly on addition of PTFE. The reduction in wear rate of PTFE modified polyester–cotton composite has been discussed with the help of SEM observations of worn surfaces and coefficient of friction.     

Effect of material state on the wear of filled polytetrafluoroethylene composite F4K20 on its basis

Tests for the wear of polytetrafluoroethylene and composites on its basis with different glass transition and softening temperatures has been performed. It has been demonstrated that a rise in temperature leads to an abrupt rise in wear due to the build up of adhesive on the metallic counterbody. The method of temperature calculations in the frictional contact zone has been developed and tested. It has been demonstrated that the introduction of filler into polytetrafluoroethylene results in a rise in the glass transition temperature from–120°C, which corresponds to polytetrafluoroethylene, to +150°C.     

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.     

Impact of Viscoelasticity on the Tribological Behavior of PTFE Composites for Valve Seals Application

In this article, we studied and explored the impact of viscoelasticity on the friction and wear behavior of pure polytetrafluoroethylene (PTFE), carbon–graphite PTFE composite, and glass fiber–MoS₂ PTFE composite. Tests were carried out using a specific reciprocating tribometer for valve seal application. The worn surfaces of the PTFE composites and the transfer films formed on the counterface were examined with a scanning electron microscope (SEM). Experimental results revealed that the addition of filler materials was effective in reducing the wear volume in all composites studied. In addition, the friction coefficient and wear resistance showed high sensitivity to the viscoelastic behavior of the PTFE seal. SEM investigation showed that the incorporation of particulate fillers into the PTFE matrix could dramatically reduce and stabilize the transfer films to the counterface, so they largely decreased the wear of the PTFE composites.     

Novel polytetrafluoroethylene (PTFE) composites with newly developed Tribaloy alloy additive for sliding bearings

A group of novel polytetrafluoroethylene (PTFE)-based composite materials are developed for sliding bearing applications. The reinforcements include the newly developed T-401 Tribaloy alloy, which possesses better ductility compared to conventional Tribaloy alloys, spherical bronze particles, chopped carbon fibers and milled graphite. The specimens are fabricated with the compression moulding technique under different preforming and sintering cycles. The mechanical and tribological properties as well as corrosion resistance of the new composites are investigated. It is demonstrated that these properties are influenced by the type of fillers and the content level of fillers. The wear resistances of all the developed PTFE composites are much higher than that of pure PTFE with very low coefficients of friction. Among the developed composites, the mixture of 40% PTFE + 15% T-401 + 45% bronze exhibits the best combination of properties.     

Influence of molecular weight on performance properties of polyethersulphone and its composites with carbon fabric

The effect of molecular weight (MW) of a polymer on the wettability of fibers and its influence on the performance properties need to be addressed in detail. Specialty polymer, viz. polyethersulphone (PES), with varying MW was selected as a matrix material to develop the composites with carbon fabric (CF). Since carbon fiber is inert towards the matrix, cold remote nitrogen–oxygen plasma (CRNOP) treatment was employed to improve its chemical reactivity, by incorporating functional groups to promote the fiber–matrix adhesion. Evaluation of mechanical and sliding wear properties of polymers and composites led to the conclusion that the CRNOP treatment was beneficial to enhance performance properties. The MW and MFI have inverse relation. MW proved to be a controlling parameter for pristine polymers while melt flow index (MFI) was the decisive parameter for the performance of composites. Perforations and increased roughness on the treated carbon fiber, as observed by the field emission scanning electron microscopy (FESEM), were responsible for the improved fiber–matrix adhesion and hence performance properties.     

Tribological Characterization of Aromatic Thermosetting Copolyester–PTFE Blends in Air Conditioning Compressor Environment

The tribological behavior of a wide range of compositions using blends of aromatic thermosetting polyester (ATSP) with polytetrafluoroethylene (PTFE) has been investigated. PTFE was chosen as the blending material because of its low coefficient of friction and good performance at high temperatures and resistance to chemicals. ATSP blends were used to specifically combat some of the shortcomings of PTFE like its extremely low wear resistance and poor mechanical properties, and special processing requirements due to its high melt viscosity. Controlled tribological experiments simulating an air conditioning compressor operating with R134a refrigerant under realistic operating conditions were carried out with different ATSP/PTFE compositions, as well as four different state-of-the-art commercially available composites containing carbon fibers, graphite and PTFE. It was found that the newly synthesized composites exhibited superb tribological characteristics as far as low friction and low wear were concerned. The wear performance of PTFE was greatly improved, while it was shown that greater amounts of ATSP used in the blend lead to lower wear and the amount of ATSP did not significantly alter the friction coefficient. Material transfer and development of a weak film on the disk surface was observed, especially for the blends with higher PTFE content.     

Mechanical and tribological properties of short-fiber-reinforced SiC composites

The short-carbon-fiber-reinforced SiC (C_sf/SiC) composites were prepared by hot-pressing sintering with Si, Al and B as sintering additives. The effects of fiber volume fraction on the mechanical and tribological properties of the C_sf/SiC composites were investigated. The results show that the bending strength values of the composites containing a certain content of the short carbon fibers are higher than that of the monolithic SiC. The friction coefficients of the composites decrease with increasing short carbon fibers content. Except of the composite containing 53 vol% short carbon fibers, the wear rates of the composites decrease with increasing short carbon fibers content, and are lower than that of the monolithic SiC drastically.     

Effect of carbon nanotube addition on the tribological behavior of carbon/carbon composites

Carbon nanotube composite coatings were applied onto carbon/carbon composites to improve wear properties. Carbon nanotubes have been prepared by catalytic pyrolysis of hydrocarbons. The nanotube slurry was prepared by addition of phenolic resin and solvent to infiltrate into C/C composites. The nanotube added composites were then carbonized in a nitrogen atmosphere. Ball-on-disc type wear tests were performed to evaluate the tribological properties of the carbon nanotube added carbon composites. The result showed that addition of nanotube has the potential to increase the wear resistance of carbon composites. Changes in Raman spectra, morphology and surface damage were studied to explain observed wear behavior.     

用于C－A1复合材料的C纤维表面多功能梯度涂层

提出一种用于Ｃ－Ａ１复合材料的Ｃ纤维表面多功能梯度涂层，它具有润湿、减缓热应力、阻挡界面反应、改善复合材料断裂形式、提高纤维抗氧化性等多种功能，可以满足Ｃ－Ａ１复合材料制造工艺与性能的多种要求。并且采用化学气相沉积工艺制备了结构和成分分布与设计相符合的涂层。将其应用于Ｃ－Ａ１复合材料获得以良好的试样抗拉强度。对于该涂层的性能与作用进行了研究。     

Friction and Wear Behavior of CF/PTFE Composites Lubricated by Choline Chloride Ionic Liquids

The use of ionic liquids (ILs) as lubricants has received increasing attention in recent years. The use of ILs, however, is limited by the corrosion problem and their potential toxic property. Here we present the results of our initial study on the tribological properties of carbon fiber (CF)-filled polytetrafluoroethylene (PTFE) composites, which have an excellent chemical resistance property, lubricated by choline chloride ILs. The difference between choline chloride ILs and water and hydraulic oil as lubricants was studied at the same time, as was the effect of the anion on the lubricating property of choline chloride ILs. The worn surface and transfer film of CF/PTFE composites were studied by scanning electron microscopy. Our results indicate that the lubricating property of choline chloride ILs is much better than that of water and hydraulic oil. The friction coefficient and wear rate of CF/PTFE composites lubricated with ILs were approximately 60 and 50 % lower than those under the dry friction condition. Among the three kinds of ILs tested, the best tribological properties of the CF/PTFE composites were found for those sliding in the mixture of 1,2-propanediol and choline chloride. The worn surface and transfer film of CF/PTFE composites were also much smoother than those under the dry friction, water lubrication, and hydraulic oil lubrication conditions.     

Deformational energy density in antifrictional fabric composites

The bulk deformational energy density is simulated in antifrictional fabric composites with an epoxy base reinforced by polytetrafluoroethylene and glass fibers in two mutually perpendicular directions. The fibers in different directions consist of different materials. The influence of the external mechanical action and the content of fibers in the composite on the bulk deformational energy density is investigated.     

Wear of PEEK composites related to their mechanical performances

A series of polyetheretherketone-based composites was investigated, blended with different contents of polytetrafluoroethylene and/or graphite, and reinforced with various amounts of short carbon fibres. The mixture of the PEEK with various fillers was achieved by twin-screw-extruders. Thereafter, the composites were finally manufactured using an injection moulding machine. Testing of the tribological properties of the PEEK composites was carried out on a block-on-ring apparatus. The dependence of mechanical properties, e.g. Charpy impact resistance, fracture toughness, flexural modulus and strength, on various filler contents of these composites was also investigated, which is believed to be of help towards a better understanding of the steps on how to improve the composite’s wear resistance.     

Recent advances in polymer composites' tribology

An overview is given on the friction and wear properties of high temperature resistant polymers, in particular polyetheretherketone (PEEK), under various testing conditions against smooth steel counterparts. The effects of internal lubricants, especially polytetrafluoroethylene (PTFE), and short fibre reinforcements (glass vs. carbon) are outlined. In addition, results of sliding wear experiments with continuous glass, carbon or aramid fibre-polymer matrix composites against steel were used to develop a hypothetical model composite with optimum wear resistance.     

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.