酸性溶液中PTW增强PTFE复合材料的耐蚀性和摩擦磨损性能

分别研究了不同含量钛酸钾晶须(PTW)、碳纤(CF)填充聚四氟乙烯(PTFE)复合材料在硫酸溶液中和干摩擦条件下摩擦学性能以及酸中的耐蚀性能,借助SEM等分析探讨了相关机理。结果表明,酸中纯PTFE耐磨性较干摩擦条件下提高了2个数量级,摩擦系数也只有干摩擦的15.3%。与CF/PTFE相比,PTW/PTFE复合材料在酸中显示更好的耐蚀和耐磨性能。PTW可以进一步提高PTFE酸中耐磨性能、降低摩擦系数。含15%（质量）PTW时复合材料具有最低的磨损率,此时比纯PTFE酸中耐磨性提高13.8倍,是相同含量CF/PTFE耐磨性的3.2倍。由于酸溶液的冷却和润滑作用,复合材料的摩擦系数与干条件相比明显降低。然而,酸溶液阻止了转移膜的形成。不管是干摩擦还是在酸性溶液中,当填料含量超过15%（质量）时,犁削和磨粒磨损是PTFE复合材料的主要磨损机理。     

不同介质中聚四氟乙烯复合材料的摩擦磨损性能

分别在碱液、水、油和干摩擦条件下考察了碳纤维和玻璃纤维填充聚四氟乙烯复合材料的摩擦磨损性能。利用SEM观察了不同介质中磨损面和对摩面的形貌,并探讨了其磨损机理。结果表明,不同介质中摩擦系数的大小关系是μ干>μ水或油>μ碱,磨损率是W水>W干>W碱或油。水、碱和油都不同程度地阻止了转移膜的形成。碱液和油具有很好的冷却与润滑作用,摩擦系数低,磨损小;然而水分子降低了填料和基体的界面粘接强度,造成犁削和磨粒磨损加重。     

Study on the Friction and Wear Behaviors of Modified PA66 Composites

The wear-resistant polyamide 66 (PA66) composites were prepared and the mechanical properties, friction and wear properties were inspected. Results show that GF, PTFE and MoS₂ can improve the mechanical, friction and wear properties of PA66 composites. PTFE is more effective on the friction and wear properties than MoS₂ when GF is 30%wt. The best effect of the modification is 35%wt GF when both PTFE and MoS₂ were added. Friction coefficient first increase, then reduce to be stable as sliding time increases. Friction coefficient and wear mass loss increase as load increases. The main wear mechanisms are fatigue and abrasion wears.     

Influence of solid lubricant reinforcement on wear behavior of Kevlar fabric composites

The friction and wear behavior of Kevlar fabric composites reinforced by PTFE or graphite powders was investigated using a Xuanwu‐III friction and wear tester at dry sliding condition, with the unfilled Kevlar fabric composite as a reference. The worn surfaces were analyzed by means of scanning electron microscope, and X‐ray photoelectron spectroscopy. It was found that PTFE or graphite as fillers could significantly improve the tribological behavior of the Kevlar fabric composites, and the Kevlar fabric composites filled with 20% PTFE exhibited the best antiwear and antifriction ability among all evaluated cases. The transfer films established with two lubricants in sliding wear of composites against metallic counterparts made contributions to reducing friction coefficient and wear rate of Kevlar fabric composites. In particular, FeF₂ generated in the sliding of Kevlar fabric composites filled with PTFE against counterpart pin improved the bonding strength between the transfer film and counterpart surface, which accounted for the lowest friction coefficient and wear rate of the Kevlar fabric composites filled with PTFE measured in the testing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

玻璃纤维填充改性PTFE复合材料的摩擦磨损性能

为改善聚四氟乙烯(PTFE)高磨耗的缺点,通过冷压烧结成型工艺制备了玻璃纤维(GF)填充改性PTFE复合材料,探究了不同GF添加比例的PTFE/GF复合材料在不同转速下的摩擦磨损情况。采用三维视频显微镜观察了样品的表面磨痕深度,并借助扫描电子显微镜观察摩擦表面形貌同时分析磨损机理。结果表明,填充GF后的PTFE复合材料其摩擦系数虽有一定程度的升高,但其体积磨损率却大幅降低。当GF质量分数为20%时,复合材料的体积磨损率降到最低,并在转速为80 r/min时较纯PTFE降低了93.56%。观察分析微观形貌发现,随着GF含量的增大,复合材料的磨损机理逐渐由纯PTFE的犁耕磨损和粘着磨损向磨粒磨损转变,当GF含量为25%时,出现轻微的疲劳磨损。     

腐蚀环境中纤维增强聚四氟乙烯复合材料的摩擦磨损性能研究

分别研究了不同含量碳纤维(CF)、玻璃纤维(GF)填充聚四氟乙烯（PTFE）复合材料在硫酸溶液中和干摩擦条件下的摩擦学性能,同时考察了PTFE复合材料在酸中的腐蚀行为,探讨了相关机理。结果表明,在酸中GF能够提高PTFE的耐磨性,比CF在提高PTFE耐磨性方面具有更好的优势。就酸溶液中的耐磨性和耐腐蚀性而言,15 %（质量分数,下同）是填料的最佳含量,此时GF和CF填充的PTFE,耐磨性分别较纯PTFE提高了7.7和4.4倍;当填料的含量超过15 %时,复合材料的耐磨性和耐腐蚀性均下降,主要是由于此时犁削和磨粒磨损是PTFE复合材料的主要磨损机制。由于酸溶液的冷却和润滑作用,硫酸溶液中PTFE复合材料的摩擦因数大幅降低,但酸溶液抑制了对磨面上转移膜的形成。     

硅灰石与石墨对聚四氟乙烯摩擦磨损性能的影响

以针状的硅灰石和鳞片石墨为填料,采用冷压—烧结工艺制备了不同填料含量的聚四氟乙烯（PTFE）复合材料,考察了复合材料的摩擦磨损性能,并利用扫描电子显微镜对磨痕和转移膜进行了分析。结果表明,单独填充硅灰石和石墨时,PTFE的磨损率都会随填料含量的增加而降低,硅灰石的作用要强于石墨;但硅灰石会使PTFE的摩擦因数明显增大,而石墨会使PTFE的摩擦因数降低;2种填料提升PTFE耐磨性的作用机理不同,硅灰石在摩擦过程中会在滑动界面区域上逐渐堆积,起到优先承担载荷的作用;而石墨在摩擦过程中会发生片层的滑移与剥离,有助于转移膜的形成;适量的硅灰石（含量为20 %,质量分数,下同）与石墨（含量为5 %或10 %）复合填充能产生协同效应,使PTFE的磨损率进一步降低,耐磨性比未填充的PTFE提高200倍。     

Tribological behavior of carbon nanotube and polytetrafluoroethylene filled polyimide composites under different lubricated conditions

The friction and wear behavior of polyimide (PI) composites reinforced with carbon nanotube (CNT) and polytetrafluoroethylene (PTFE) were comparatively evaluated under dry sliding, water‐, oil‐ or alkali‐lubricated condition. The wear mechanisms of the composites were also discussed. Results indicate that, when comparison with the dry friction situation, PI‐based composites results lower friction coefficients and wear rates under oil‐ or alkali‐lubricated condition. The lowest wear rate of the CNT/PTFE/PI composite is recorded as 1.2 × 10⁻⁶ mm³/Nm during the composite sliding in alkali, which is only about 40% of the value sliding under dry friction condition. The worn surface of neat PI under dry sliding is characterized by severe adhesive wear, whereas abrasive wear is the main character for CNT/PTFE/PI composites. The worn surfaces of CNT/PTFE/PI composites sliding in oil or alkali lubricated condition are smoother than those under dry or water condition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Tribological and mechanical properties of carbon‐nanofiber‐filled polytetrafluoroethylene composites

The effects of various filler concentrations (0.1, 0.5, 1, 1.5, 2, 2.5, and 3 wt %) on the tribological and mechanical properties of carbon‐nanofiber (CNF)‐filled polytetrafluoroethylene (PTFE) composites were studied. Moreover, the influence of various loads (50, 100, 150, and 200 N) and sliding velocities (0.692 and 1.39 m/s) on the friction and wear behaviors of the PTFE composites was investigated. The results showed that the friction coefficients of the PTFE composites decreased initially up to a 0.5 wt % filler concentration and then increased, whereas the antiwear properties of the PTFE composites increased by 1–2 orders of magnitude in comparison with those of pure PTFE. The composite with a 2 wt % filler concentration had the best antiwear properties under all friction conditions. The friction coefficients of the CNF/PTFE composites decreased with increases in the load and sliding velocity, whereas the wear volume loss of the PTFE composites increased. At the same time, the results also indicated that the mechanical properties of the PTFE composites increased first up to a 1 wt % filler concentration and then decreased as the filler concentration was increased above 1 wt %. In comparison with pure PTFE, the impact strength, tensile strength, and elongation to break of the PTFE composites increased by 40, 20, and 70%, respectively, at a 1 wt % filler concentration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2430–2437, 2007     

Tribological behaviors of polytetrafluoroethylene composites under dry sliding and seawater lubrication

The composites of polytetrafluoroethylene (PTFE) filled with expanded graphite (EG), poly(p‐oxybenzoyl) (POB), and basalt fiber (BF) were prepared by heating compression and sintering molding. The tribological behavior of PTFE composites was investigated with a pin‐on‐disk tester under dry conditions and seawater lubrication. The worn surface of PTFE composites and the transfer film on the counterface were observed with a scanning electron microscope. The results indicated that the incorporation of EG and POB improved the hardness of PTFE composites, and addition of BF led to greater load‐carrying capacity. Compared to pure PTFE, the coefficients of friction of PTFE composites slightly increased, but the wear rates were significantly reduced (the wear rate of composite with 3% EG being only 10.38% of pure PTFE). In addition, all the composites exhibited a lower coefficient of friction (decreases of about 0.03–0.07) but more serious wear under seawater lubrication than under dry sliding. The wear mechanism changed from serious abrasive wear of pure PTFE to slight adhesion wear of PTFE composites under both conditions. A transfer film was obviously found on the counterface in seawater, but it was not observed under dry conditions. Among all the materials tested, the PTFE‐based composite containing 20% POB (mass fraction), 2% EG, and 3% BF exhibited the best comprehensive performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2523–2531, 2013     

Mechanism of filler action in reducing the wear of PTFE polymer by differential scanning calorimetry

Two types of representative nanometer materials, i.e., fibroid nanometer attapulgite and approximate spherical ultrafine diamond, were selected as fillers of polytetrafluoroethylene (PTFE) to study the mechanism of the wear‐reducing actions of the fillers in PTFE composites. The friction and wear tests were performed on a block‐on‐ring wear tester under dry sliding conditions. Differential scanning calorimetry (DSC) was used to investigate material microstructure and to examine modes of failure. No significant change in coefficient of friction was found, but the wear rate of PTFE composites was orders of magnitude less than that of pure PTFE. DSC analysis revealed that nanometer attapulgite and ultrafine diamond played a heterogeneous nucleation role in PTFE matrix and consequently resulted in increasing the crystallinity of PTFE composites. Moreover, the PTFE composite with higher heat absorption capacity and crystallinity exhibited improved wear resistance. A propositional “sea‐frusta” frictional model explained the wear mechanism of filler action in reducing the wear of PTFE polymer, i.e., fillers in the PTFE matrix effectively reduced the size of frictional broken units for PTFE composites and restrained the flowability of the units, as well as supporting the applied load. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of various kinds of fillers on the tribological behavior of polytetrafluoroethylene composites under dry and oil‐lubricated conditions

Polytetrafluoroethylene (PTFE)‐based composites filled with various inorganic fillers in a volume fraction of 30% were prepared. The tribological behavior of the PTFE composites sliding against AISI52100 steel under dry and liquid paraffin‐lubricated conditions was investigated on an MHK‐500 model ring‐on‐block test rig. The morphologies of worn surfaces and wear debris were observed with a scanning electron microscope (SEM) and an optical microscope. As the results, different fillers show different effects on the tribological behavior of the PTFE composites, while the composite shows much different tribological behavior under lubricated conditions as compared with dry sliding. The tribological behavior of the PTFE composites under dry sliding is greatly related to the uniformity and thickness of the transfer films. Only the PTFE composites with a transfer film of good uniformity and proper thickness may have excellent tribological behavior. The PTFE composites show much better tribological behavior under lubrication of liquid paraffin than under dry sliding, namely, the friction coefficients are decreased by 1 order of magnitude and the wear rate by 1–3 orders of magnitude. Observation of the worn composite surfaces with SEM indicates that fatigue cracks were generated under lubrication of liquid paraffin, owing to the absorption and osmosis of liquid paraffin into the microdefects of the PTFE composites. The creation and development of the fatigue cracks led to fatigue wear of the PTFE composites. This would reduce the mechanical strength and load‐supporting capacity of the PTFE composites. Therefore, the tribological behavior of the PTFE composites under lubrication of liquid paraffin is greatly dependent on the compatibility between the PTFE matrix and the inorganic fillers. In other words, the better is the compatibility between PTFE and fillers the better is the tribological behavior of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1891–1897, 2001     

Tribological properties of PTFE‐filled PMIA

The polytetrafluoroethylene‐filled (PTFE) poly(m‐phenylene isophalamide) (PMIA) composite blocks are prepared by compression molding. The friction and wear of PTFE‐filled PMIA are investigated on a block‐on‐ring machine by running the PMIA composite block against plain carbon steel (AISI 1045 steel ring). The worn surface of PMIA composite and the steel counterface are examined by using electron probe microanalysis (EPMA). It is found that PTFE‐filled PMIA exhibited considerably lower friction coefficient and wear rate than pure PMIA. Furthermore, the lowest wear rate is obtained when the composite contains 20 vol % PTFE. EPMA investigations show that there are some debris that could restrain the wear of the PMIA composites oriented along the sliding track and embedded in the surface of PMIA composite. A kind of stripe transfer film that contains abundant F element should be the main reason for the improvement of the tribological properties of PTFE‐filled PMIA composites. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 747–751, 1999     

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     

Effect of solid lubricants on tribological behavior of glass fiber reinforced polyamide 6

The tribological properties of glass fiber reinforced polyamide 6 (GF/PA6, 15/85 by weight) and its composites filled with solid lubricants were investigated. The main purposes of this article were to study the hybrid effect of solid lubricants with glass fiber as well as the synergism of combined solid lubricants, the wear mechanisms were studied by SEM. The results showed that graphite impaired the tribological properties of GF/PA6, but the tribology behavior of graphite filled GF/PA6 composite could be significantly improved by polytetrafluroethylene (PTFE) or/and ultrahigh molecular weight polyethylene (UHMWPE), and the GF/PA6 composite filled with 5 wt % graphite, 5 wt % PTFE together with 5 wt % UHMWPE exhibited the lowest friction coefficient and wear rate, which was almost a reduction in friction coefficient by 37% and in wear rate by 34% contrast to GF/PA6. The effect of load was also studied, and the results showed that the friction coefficient was virtually not affected by load, while the wear rate all increased with increasing load. POLYM. COMPOS., 34:1783–1793, 2013. © 2013 Society of Plastics Engineers     

Tribological properties of porous PPS/PTFE composite filled with mesopore titanium oxide whisker

Nano‐micro hierarchical porous polyphenylene sulfide/polytetrafluoroethylene (PPS/PTFE) composites were prepared by mold‐leaching and vacuum melting process under high temperature condition. The tribological behaviors of porous PPS/PTFE composites and the synergism as a result of incorporation of both micro‐porogen (NaCl) and mesoporous TiO₂ whiskers were investigated. The effects of mesoporous TiO₂ whiskers and nonperforated TiO₂ whiskers on the friction and wear properties of PPS/PTFE composites were comparatively studied, respectively. Results indicated that the wear rate of porous PPS/PTFE composites with 30 wt % NaCl and 7 wt % mesoporous TiO₂ whiskers obtained the lowest values under the load of 100 N. Compared with pure PPS, the wear resistance of nano‐micro porous PPS/PTFE composite was enhanced by 6.45 × 10³ times, showing outstanding wear resistance. During sliding condition, grease could be squeezed through the nano‐micro pores under the coupling effect of load and friction heat, and formed a lubricanting layer on friction surface, providing self‐lubricating effect and high wear resistance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

聚四氟乙烯填充聚醚醚酮及其复合材料的研究

利用熔融共混工艺制备了ＰＥＥＫ／ＰＴＦＥ共混物及其复合材料,研究了ＰＴＦＥ对ＰＥＥＫ共混物及其复合材料力学性能和耐磨性的影响,结果表明,ＰＥＥＫ经１０％￣ＰＴＦＥ填充改性,玻纤／碳纤混杂增强后,由于磨损方式的改变,使该复合材料不仅保持了良好的物理力学性能,而且具有较低的摩擦系数,耐磨性也得到明显改善。     

Mechanical and tribological properties of polyoxymethylene modified with nanoparticles and solid lubricants

Polyoxymethylene (POM) composites modified with nanoparticles, polytetrafluoroethylene (PTFE) and MoS₂ were prepared by a twin‐screw extruder. The effect of nanoparticles and solid lubricant PTFE/MoS₂ on mechanical and tribological properties of the composites were studied. Tribological tests were conducted on an Amsler friction and wear tester using a block‐on‐ring arrangement under dry sliding and oil lubricated conditions, respectively. The results showed that generally speaking POM nanocomposites had better stiffness and tribological properties than corresponding POM composites attributed to the high surface energy of nanoparticles, except that the tensile strength of three composites and dry‐sliding tribological properties of POM/3%Al₂O₃ nanocomposite decreased due to the agglomeration of nanoparticles. Tribological properties differed under dry sliding and oil lubricated conditions. The friction coefficient and wear volume of POM nanocomposites under oil lubricated condition decreased significantly. The increased deformation resistance supported the increased wear resistance of POM nanocomposites. POM/PTFE/MoS₂/3%Al₂O₃ nanocomposite had the best mechanical and tribological properties of all three composites, which was attributed to the synergistic effect of nanoparticles and PTFE/MoS₂. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

The effect of interface modification between POM and PTFE on the properties of POM/PTFE composites

A plasma technique was applied to modify the surface of polytetrafluoroethylene (PTFE) fiber to improve the compatibility between PTFE and polyacetal (POM). This technique used argon (Ar) plasma to treat PTFE fiber first and then grafting the fiber with acrylic acid (AAc) by peroxidation. The Ar plasma‐treated PTFE (PPTFE) fiber and AAc‐grafted PPTFE (AAc‐g‐PPTFE) fiber were added into POM to increase the wear resistance and to decrease the friction coefficient of POM. The variables of the experiments were plasma treatment time, monomer concentration of AAc, and grafting time. The graft copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The stress–strain behavior, impact strength, Taber wear factor, friction coefficient, and morphology of composites were also investigated. The properties of POM/PTFE composites could be successful modified by surface modification of PTFE in this investigation. The impact strength of POM/AAc‐g‐PPTFE composites was more than twice of that of POM/PTFE composites. The Taber wear factor and friction coefficient of POM/AAc‐g‐PPTFE composites decreased markedly. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 800–807, 2000     

Mechanical and tribological properties of PA66/PPS blend. III. Reinforced with GF

Based on previous work, 70 vol % PA66/30 vol % PPS blend was selected as a matrix, and the PA66/PPS blend reinforced with different content of glass fiber (GF) was prepared in this study. The mechanical properties of PA66/PPS/GF composites were studied, and the tribological behaviors were tested on block‐on‐ring sliding wear tester. The results showed that 20–30 vol % GF greatly increases the mechanical properties of PA66/PPS blend. When GF content is 20 vol %, the friction coefficient of composite is the lowest (0.35), which is decreased by 47% in comparison with the unfilled blend. The wear volume of the GF‐reinforced PA66/PPS blend composite decreases with the increase of GF content. However, the wear‐resistance is not apparently improved by the addition of GF in the experimental range for comparison with unfilled PA66/PPS blend. The worn surface and the transfer film on the counterface were examined by scanning electron microscopy (SEM). The observations revealed that the friction coefficient of composite depends on the formation and development of a transfer film. The wear mechanism involves polymer matrix wear and fiber wear. The former consists of melting wear and plastic deformation of the matrix, while the latter includes fiber sliding wear, cracking, rupturing, and pulverizing. The contributions of the matrix wear and the fiber wear determine the ultimate wear volume of PA66/PPS/GF composite. In addition, the abrasive action caused by the ruptured glass fiber is also a very important factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 523–529, 2006