聚醚醚酮(PEEK)及其在压缩机气阀上的应用

详细介绍了聚醚酮类(PAEK)塑料中的聚醚醚酮(PEEK)的结构、性能，论述了这类新材料的工业应用技术进展概况，总结了实际应用对比试验结果。     

Carbon fiber reinforced polyether ether ketone composite as a bearing surface for total hip replacement

This paper investigates the tribological performance of a carbon fiber reinforced PEEK composite as a bearing surface for total hip replacement. Extensive hip joint simulator tests were conducted to optimize the microstructure of the composite and the counterface material. A softer and more graphitic carbon fiber is preferred to a harder and more abrasive fiber. A ceramic counterface is preferred to a metal counterface. An excellent wear couple was identified to be a 30 wt% pitch-based carbon fiber reinforced PEEK composite acetabular insert articulating against a zirconia ceramic head. When tested on a hip simulator run for 10 million cycles, a reduction in the wear rate of almost two orders of magnitude was achieved with this wear couple in comparison to a conventional UHMWPE/metal or UHMWPE/ceramic couple.     

Tribological studies of poly(ether ether ketone) blends

A review of friction and wear studies of poly(ether ether ketone) (PEEK) blended with other polymers is presented. PEEK is a high performance thermoplastic now commonly employed in many engineering applications, but its tribological properties deteriorate in high temperature environments. One approach to improving the friction and wear properties of PEEK is to blend this plastic with appropriate polymers. In recent years, a number of investigations into the tribology of PEEK blended with poly(ether imide) (PEI), polytetrafluoroethylene (PTFE) and liquid crystalline polymers (LCPs) have been reported and these studies are discussed.     

Elevated pitting wear of injection molded polyetheretherketone (PEEK) rolls

The increased pitting wear of PEEK rolls applied as bearing elements in drawer guide rails was investigated. Similar to findings for PEEK gear wheels the increased pitting occurred only in the presence of lubricants. Simple assumptions found in literature to explain this effect for PEEK gear wheels could be disproved within this research. Moreover, high irreversible deformations during the rolling process of PEEK rolls which were observed in a previous study were shown to not influence the mechanical properties of the surface material significantly. Additionally, the chemical analysis of the tribological system with Raman spectroscopy excluded a chemical reason for the intensified pitting. A detailed microscopic analysis of unstressed PEEK rolls combined with microtome cuts of the surfaces showed distinct pre-cracks in the outermost surface region which were not visible to the naked eye. Assuming a crack growth mechanism that was strongly supported by the fluid pressure of grease enclosed in the surface pre-cracks the injection molding process was adapted in order to improve the surface quality of the PEEK rolls. By this way the fatigue lifetime of the latter was increased by a factor of 2–3 which was crucial for the practical application.     

Behavior of ultrathin liquid lubricant films for contact sliders in hard disk drives

In this paper, we describe the behavior of ultrathin liquid lubricant films for contact sliders in hard disk drives. In the experiments, the ultrathin liquid lubricant film behavior is investigated using Zdol and cyclotriphosphazene-terminated PFPE lubricant which have different end groups as a function of lubricant film thickness. The disks are examined with a scanning microellipsometer before and after contact slider experiments. It is found that the lubricant film thickness profiles almost do not change, when the lubricant film thickness is less than one monolayer. It can also be observed that lubricant film thickness instability due to dewetting occurs as a result of slider-disk contacts for the tested lubricants and the films undergo spontaneous redistributions, resulting in significantly nonuniform film thickness profiles, when the lubricant film thickness is thicker than one monolayer. In addition, it is found that the observed behavior of ultrathin liquid lubricant films for cyclotriphosphazine-terminated PFPE lubricant contrasts markedly with that for Zdol. The difference between cyclotriphosphazene-terminated PFPE lubricant and Zdol is only the functional end group. Therefore, it may be concluded that their unstable lubricant behavior depends on the chemical structure of functional end groups.     

On sliding friction and wear of polyetheretherketone (PEEK) composites at elevated temperatures

The friction and wear behaviour of polyetheretherketone (PEEK) composites, incorporating different amounts of short carbon fibres with different surface treatments, was studied under dry sliding conditions against smooth steel on a pin-on-disc apparatus at different temperatures. Wear of the composites was reduced considerably in all cases, but, whatever the surface treatment, wear increased with increasing temperature for all proportions off fibres. For minimum friction coefficient there was an optimum proportion of fibre volume fraction of about 10 vol.%. The effect of the fibre surface treatment was not significant for the tribological behaviour of the PEEK composites. To predict wear performance, a wear model proposed by Friedrich and Voss seemed to work properly, and, furthermore, a friction model was developed to predict the friction behaviour of PEEK composites with short carbon fibres.     

Erosive wear of ductile metals by a particle-laden high velocity liquid jet

A liquid-solid particle jet impingement flow apparatus is described and experimental measurements are reported for the accelerated erosion of copper, aluminum and mild steel sheet metal by coal suspensions in kerosene and Al₂O₃ and SiC suspensions in water. Slurry velocities of up to 130 ft s^?1 (40 m s^?1) and impingement angles of 15°–90° were investigated. The maximum particle concentration used was 40 wt.%. For high velocity the results of this work show two erosion maxima; these are found at impingement angles of 90° and 40°. However, in corresponding gas-solid particle investigations maximum erosion occurs at approximately 20°. In this work both particle concentration and composition were varied. A polynomial regression technique was used to calculate empirical and semitheoretical correlation constants.     

Effect of the reinforcement (carbon or glass fibres) on friction and wear behaviour of the PEEK against steel surface at long dry sliding

PEEK (poly-ether-ether-ketone) is a high performance engineering semicrystalline thermoplastic. PEEK has excellent tribological behaviour, which is optimised in the specially formulated tribological composite grade.This paper presents a comparative study of wear and friction on PEEK, PEEK-CF30 (wt%) and PEEK-GF30 (wt%) against steel, at long dry sliding. A plan of experiments was performed on a pin-on-disc machine, under the following conditions $pv=2\text{MPa}\text{m/s}$ (p = 8 MPa and $v=0.25\text{m/s}$; p = 2.68 MPa and $v=0.75\text{m}\text{/}\text{s}$) at the ambient temperature for a sliding distance of 15 km.PEEK-CF30 presented the lesser friction coefficient followed by PEEK. PEEK-GF30 presented the higher friction coefficient throughout all sliding distance. Both PEEK-CF30 and PEEK-GF30 have presented an excellent wear resistance relatively to PEEK while PEEK-CF30 presented the best tribological behaviour.     

Precise and reproducible deposition of thin and ultrathin carbon films by flash evaporation of carbon yarn in high vacuum

A simple, small device and its use for reproducible flash evaporation of carbon yarn in high vacuum are characterized. Using this flash evaporator, carbon films of any thickness up to 20 nm can be deposited without spark generation under minimized photon radiation, and with an accuracy better than ±0·2 nm. The films have less background structure (imaged in phase contrast) than conventionally rod evaporated films and are therefore suitable for many kinds of thin and ultrathin carbon film applications in electron microscopy, e.g. as backing for formvar films or sections, as isolating carbon layers for autoradiography, as ultrathin films (floated from mica) for support of macromolecules to be metal shadowed and as support and cover for negative staining of various specimens by the sandwich technique.     

Effects of sliding velocity and applied load on the tribological mechanism of amorphous poly-ether–ether–ketone (PEEK)

In this work, the effects of sliding velocity and applied load on the tribological characteristics, i.e. friction coefficient and wear rate, of an amorphous poly-ether–ether–ketone (PEEK) coating was examined. Friction tests were performed on a ball-on-disc apparatus. Based on analyses of the worn tracks, a comprehensive attempt is made to approach the tribological mechanism of amorphous PEEK. A hypothesis is proposed that the tribological behaviour of the amorphous PEEK is closely related to its viscoelastic behaviour. The sliding velocity plays significant roles on the tribological characteristics by influencing the interface temperature and strain rate of the PEEK surface layer involved in the friction process. The applied load influences the tribological performance by varying the strain range in the surface layer.     

高效液相色谱法测定花生中的黄曲霉毒素

黄曲霉毒素(AFT)的急性毒性很强,是重要的致癌物质。本文用甲醇水溶液提取花生样品中的AFT,提取液经过过滤、稀释后,用免疫亲和柱净化,以甲醇洗脱,用高效液相色谱法直接测定。方法的回收率为87％～101％,RSD<4％。     

Reflection contrast microscopy for high resolution detection of (3)H-estradiol in ultrathin sections of human stratum corneum

A single autoradiographical method for light and electron microscopy (LM and EM) is presented. Human skin, containing (3)H-estradiol ((3)H-E2) after an in vitro permeation experiment, was processed via a non-extractive tissue preparation protocol, comprising cryo-fixation, freeze-drying, osmium tetroxide vapor fixation, and Spurr resin embedding. Semithin sections were processed for LM autoradiography, while ultrathin sections were processed both for high-resolution LM and EM autoradiography. The autoradiographs were visualized by bright-field microscopy (BFM), reflection contrast microscopy (RCM), and transmission electron microscopy to evaluate the potentials of RCM visualization in high-resolution LM autoradiography. RCM visualization of ultrathin vs. semithin resin sections showed an improved stratum corneum morphology. Histological staining was superfluous. The localization of (3)H-E2 in human stratum corneum using high-resolution LM autoradiography and RCM was as accurate as with high-resolution EM autoradiography.     

Effects of contact pressure,molecular weight,and supplier on the wear behavior and transfer film of polyetheretherketone (PEEK)

Polyetheretherketone (PEEK) is a designation given to materials of the polyaryletherketone family having a characteristic distribution of ether and ketone groups in the polymer backbone. PEEK materials have high strength and chemical resistance as well as very high melting points and glass transition temperatures. Because of this combination of properties, PEEK materials find use for wear application in extreme environments where they provide a light-weight and corrosion resistant bearing material that often does not require lubrication. This study focused on determining the effects of supplier and molecular weight on the wear of particular PEEK materials, in addition to the effect of contact pressure. Multidirectional wear testing was performed on four PEEK materials. The materials were obtained from two different suppliers, and two molecular weights were chosen for each supplier. Extensive analysis of transfer films produced during wear testing was performed using optical microscopy. White light profilometry was used to measure transfer film thickness in order to calculate a mean film thickness for given experimental conditions. Dynamic mechanical analysis, as well as gel permeation chromatography and differential scanning calorimetry were used to characterize each material's viscoelastic behavior, molecular weight, and crystallinity, respectively. It was found that the wear of PEEK materials was significantly affected by both contact pressure and molecular weight, but not by supplier. However, an interaction was observed that showed the low molecular weight material from one of the suppliers was more vulnerable to wear at high contact pressures than the other three materials. Results of transfer film analysis showed that film thickness was greatest in locations where pin sliding direction was perpendicular to the counterface roughness direction, but that mean transfer film thickness did not correlate to wear amounts. This work is significant because it highlights the fact that tribologically relevant polymers, such as PEEK materials, vary greatly in terms of their polymer morphology and processing history, and this variation must be recognized by investigators when reporting wear data.     

Optimisation of electron-beam surface hardening of cast iron for high wear resistance using the Taguchi method

The paper presents the application of the Taguchi method to develop an optimised electron-beam surface hardening of cast iron for high wear resistance. The experiments were conducted on both the ductile and grey cast iron. The factors investigated during the surface-hardened process included the material matrix, the accelerating voltage, the electrical current, the travel velocity, the melted width, the beam oscillation, and the post-heat treatment temperature. In this study, the L18 and L9 orthogonal arrays were introduced through the two-stage experimental designs and trials. Smaller-is-better was used as a quality characteristic to evaluate the experimental results by computing their signal-to-noise (S/N) ratios of the wear volume after wear tests.It was found that using the Taguchi method coupled with a two-round experimental design strategy is simple, effective and efficient in developing an optimised EB surface hardening process. The experimental results show that the most important process parameters identified are the accelerating voltage, the travel speed, the electrical current and post-heat treatment, respectively. The best wear resistance result obtained through the best combination of process parameters is 8.845×10⁸ kg-mm/mm³.     

纳米和微米SiO2颗粒对PPESK复合材料摩擦学性能的影响

用热压成型法制备了纳米、微米SiO2填充聚醚砜酮(PPESK)复合材料,考察了复合材料的硬度和抗弯强度,并研究了干摩擦条件下纳米、微米SiO2颗粒对复合材料摩擦磨损性能的影响,用扫描电镜观察分析了复合材料磨损表面形貌及磨损机理。结果表明：干摩擦条件下,纳米SiO2填充PPESK主要是轻微的磨粒磨损;而微米SiO2填充PPESK主要是严重的磨粒磨损。     

Evaluation of surface roughness and nanostructure of indium tin oxide (ITO) films by atomic force microscopy

Indium tin oxide was deposited on a glass (soda lime glass) by radiofrequency sputtering system at different sputtering gas (argon/oxygen 90/10%) pressures (20-34 mTorr) at room temperature. The sputtering rate was affected by the sputtering gas pressure. The optimum sputtering gas pressure was found to be 27 mTorr. The samples at different thicknesses (168, 300, 400, 425, 475, 500 and 630 nm) were deposited on the substrate. Transparency, electrical conductivity and surface roughness of the films were characterized. The samples were annealed at 350, 400 and 450 degrees C to evaluate annealing process effects on the concerned parameters and, therefore, the above-mentioned measurements were repeated again. The films exhibited reasonable optical transmittance and electrical conductivity and greatly improved after annealing. The characterization was focused on the scanning of the film surfaces before and after annealing, which has a prominent effect on the optical properties of the films. Film surfaces were scanned by scanning probe microscopy in contact atomic force mode. The most consideration was devoted to image analysis.     

Boundary Lubrication of Oxide Surfaces by Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) in Aqueous Media

In this work, we have explored the application of poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) as an additive to improve the lubricating properties of water for metal-oxide-based tribo-systems. The adsorption behavior of the polymer onto both silicon oxide and iron oxide has been characterized by optical waveguide lightmode spectroscopy (OWLS). Several tribological approaches, including ultra-thin-film interferometry, the mini traction machine (MTM), and pin-on-disk tribometry, have been employed to characterize the frictional properties of the oxide tribo-systems in various contact regimes. The polymer appears to form a protective layer on the tribological interface in aqueous buffer solution and improves both the load-carrying and boundary-layer-lubrication properties of water.     

The friction and wear behavior of 2-(n-alkyldithio)-benzimidazole as additives in liquid paraffin

Three 2-(n-alkyldithio)-benzimidazoles were synthesized. The friction and wear behavior of the synthetic compounds as additives in liquid paraffin were examined with a four-ball machine, with emphasis on revealing the relationship between the chain length of the additive and the friction-reducing ability and lubricating mechanism of the additives. The film formed by the additive during the sliding process was investigated by using X-ray photoelectron spectroscopy. It was found that the synthetic compounds as additives in liquid paraffin had good antiwear performance. The longer the chain length of the synthetic compound, the more stable or less volatile is the compound and the more effective it is in improving wear resistance. This revised version was published online in July 2006 with corrections to the Cover Date.     

铝材冷轧润滑剂（添加剂）润滑性能评价

本文从油膜强度、摩擦系统、轧制压力及轧后退火表面光亮度等方面对铝材冷轧润滑用添加剂的润滑能进行了评价，其中，添加剂有单一的脂肪酸、醇、脂肪酸酯以及它们的复合物。结果表明：结果表明：复合添加剂的作用效果优于单一添加剂，而且其作用效果取决于单体添加剂的选择和复合比例。