聚四氟乙烯改性聚酮摩擦磨损性能的研究

研究了不同聚四氟乙烯(PTFE)微粉质量分数改性聚酮(PK)的力学性能及摩擦磨损性能,并分析了其在不同润滑条件下的摩擦磨损机理。结果表明:填充PTFE微粉后PK的拉伸强度、压缩强度和邵氏硬度下降;在干摩擦条件下,随着PTFE微粉质量分数的增加,PK复合材料的摩擦因数和磨痕宽度呈下降趋势,当PTFE微粉质量分数为6%时,转移膜最连续,磨痕宽度最低,磨损过程以黏着磨损为主;在油润滑条件下,润滑油和PTFE微粉协同作用,PK复合材料的摩擦因数和磨痕宽度均较干摩擦时明显下降。     

PTFE微粉改性聚醚醚酮摩擦磨损性能及应用研究

采用常温机械共混、高温模压的方法,制备了不同质量分数聚四氟乙烯(PTFE)微粉和碳纤维改性的聚醚醚酮(PEEK)复合材料,对其压缩强度、摩擦磨损性能进行了研究,并分析了其磨损后的表面形貌。结果表明:随着PTFE微粉质量分数的增加,PEEK复合材料的压缩强度呈下降趋势,当PTFE微粉质量分数为40%时,其压缩强度下降至60 MPa。随着聚碳纤维质量分数的增加,PEEK复合材料的压缩强度呈上升趋势。随着PTFE微粉和碳纤维质量分数的增加,PEEK复合材料的干摩擦因数和磨痕宽度逐渐下降,当PTFE微粉质量分数为40%时,PEEK复合材料干摩擦因数下降至0.21,其干摩擦磨痕宽度略有上升。随着碳纤维质量分数的增加,PEEK复合材料在油润滑条件下摩擦因数和磨痕宽度较低并略有下降。PEEK复合材料在干摩擦条件下的磨损机制以磨粒磨损为主,伴有疲劳磨损;在油润滑时,摩擦面可形成稳定连续的润滑膜而保持光滑。PEEK复合材料具有较高的压缩强度,摩擦磨损性能良好,可以制作各种滑动轴承、密封圈等特种机械零部件。     

纳米氧化铝改性聚四氟乙烯的摩擦磨损性能研究

以纳米Al2O3作为填料填充改性聚四氟乙烯(PTFE),采用模压烧结成型的方法制备了不同纳米Al2O3含量的PTFE/纳米Al2O3复合材料,考察了偶联剂改性前后纳米Al2O3及其含量对复合材料硬度、摩擦系数和磨痕宽度的影响,并利用扫描电子显微镜对复合材料的磨屑和磨损表面进行了微观分析。结果表明,随着纳米Al2O3含量的增加,复合材料的硬度和摩擦系数逐渐增大,磨痕宽度先大幅下降而后略有增加。另外,相对于未改性纳米Al2O3,PTFE/偶联剂改性纳米Al2O3复合材料的硬度和摩擦系数均较低,其磨痕宽度则较高。     

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。     

一体化成型耐磨复合材料的磨损性能研究

将耐磨涂层与树脂基复合材料采用RTM工艺一体化成型,并对一体化成型复合材料的耐磨性能进行了测试分析,采用三维白光干涉表面形貌仪测试了磨损试样的表面形貌,采用激光粒度分析仪对所使用的硬质粉体进行了粒度分析,采用电子显微镜观测了耐磨复合材料的内部结构。结果表明,复合材料试样的摩擦系数与磨痕深度情况相一致,即试样的摩擦系数越小,其磨痕深度也越小。一体化成型耐磨复合材料表面涂层的连续相为树脂基体,限制了该种复合材料在高速摩擦条件下的使用。     

玻璃纤维及石墨增强聚四氟乙烯复合材料摩擦磨损性能的研究

用机械混合、冷压成型和烧结的方法制备了不同质量分数(5%~30%)的玻纤和石墨填充聚四氟乙烯(PTFE)复合材料制品。用M-2000型磨损试验机评价了不同样品在干摩擦下的磨损性能,揭示了填料玻纤和石墨对PTFE复合材料磨损性能的影响,并对磨损机理进行了探讨。用扫描电镜(SEM)对试样磨损形貌进行观察。结果表明:对玻纤进行改性能极大地提高PTFE复合材料的耐磨性能,同时可提高复合材料硬度;玻纤和石墨协同作用,对改善PTFE摩擦磨损性能有比较显著的效果;20%玻纤 10%石墨填充PTFE复合材料有着较好的摩擦磨损性能。     

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。     

碳纤维和纳米氮化硼增强聚醚醚酮/聚四氟乙烯复合材料的摩擦学性能研究

以碳纤维（CF）为增强相，添加不同含量的纳米氮化硼（h-BN），通过注塑成型的方式，制备了聚醚醚酮/聚四氟乙烯（PEEK/PTFE）复合材料样条，使用力学试验机进行拉伸试验，利用摩擦试验机进行表面摩擦试验，并利用白光仪对磨痕数据和三维形貌进行观测，使用SEM对磨痕进行观测与分析。结果表明：随着h-BN含量的增加，PEEK/PTFE复合材料样条最大应力先增加后减小；当h-BN含量分别为3%、6%时，PEEK/PTFE复合材料样条的最大应力分别为174 MPa、165 MPa。与PEEK/PTFE相比，单独添加CF的样品摩擦系数降至0.23。同时添加CF、h-BN时，复合材料样条的摩擦系数均降低；h-BN含量分别为3%、6%时，复合材料样条的摩擦系数分别为0.06、0.09。随着h-BN含量的升高，PEEK/PTFE/CF/h-BN复合材料的磨损率先降低后升高。h-BN含量为3%时，复合材料样条的磨损率最低。     

Al2O3/PTFE复合材料的磨损性能研究

用机械共混、冷压成型烧结的方法制备了Al2O3／PTFE复合材料试样。用MM-200型磨损试验机测试了在干摩擦定载荷条件下各试样的磨损性能；用扫描电子显微镜(SEM)对磨损试样的表面形貌和磨屑的形貌进行了观察和分析；用光学显微镜对磨损后偶件环的表面形貌作了观察分析。结果表明：在实验条件下，Al2O3／PTFE复合材料的抗磨损性能，随Al2O3用量的增大逐渐增强，当Al2O3用量大于35％后，抗磨损性能增强的趋势明显减缓；在干摩擦条件下Al2O3／PTFE复合材料主要发生粘着磨损和磨粒磨损，且随Al2O3用量的增加，磨粒磨损所起的作用也增大。     

PTFE/POB共混材料的压缩回复和耐磨性能研究

采用冷压烧结工艺制备了聚四氟乙烯/聚苯酯(PTFE/POB)共混材料,主要研究了POB含量对PTFE/POB复合材料压缩回复性能和耐磨性能的影响。结果表明,复合材料的压缩回复性能在POB质量分数为20%时达到最优;与纯PTFE相比,PTFE/POB共混材料的压缩率降低了58.93%,回复率提高了24.72%;加入POB后,PTFE/POB共混材料摩擦系数随POB含量的增加有所上升,但磨痕宽度、磨损体积和磨损率随POB含量的增加而大幅度减小;当POB质量分数为20%时,与纯PTFE相比,共混材料的磨痕宽度、磨损体积和磨损率分别降低了78.1%,98.8%和98.6%。     

Influence of organic montmorillonite nanoparticles on the microstructures and thermal and tribological properties of polyethersulfone and polytetrafluoroethylene composites

Because of high wear rate and low thermal deformation temperature, the generalization and application of polytetrafluoroethylene (PTFE) in the field of tribology is restrained to a certain extent. In order to improve the wear resistance and thermal stability of this self‐lubricating polymer, organic montmorillonite (OMMT) nanoparticle reinforced polyethersulfone (PES) and PTFE ternary composites were prepared by the cold molding and vacuum sintering technology. The effects of sodium montmorillonite (Na‐MMT) and OMMT on the microstructures, thermal stabilities and tribological properties of PTFE composites were comparatively studied. The results show that the thermal stability of the PES/PTFE composites is clearly improved by the incorporation of OMMT nanoparticles. Not only the friction coefficients but also the wear rates of OMMT/PES/PTFE composites are less than those of Na‐MMT/PES/PTFE composites under identical tribological tests. Of all these PTFE composites, the PES/PTFE composite containing 10.0 wt% OMMT nanoparticles exhibits the best friction and wear properties (μ = 0.14, k = 5.78 × 10^?15 m³ N^–1 m^?1). This can be attributed to the existence of a polymer multicomponent layer consisting of PTFE, PES and OMMT on the composite surface as well as the formation of uniform PTFE transfer film on the worn surfaces of metal counterparts.     

混杂填料增强聚四氟乙烯复合材料的摩擦学性能研究

采用MM-200型摩擦磨损试验机对纳米SiC、MoS2和石墨填充聚四氟乙烯(PTFE)复合材料在干摩擦条件下与45#钢对摩时的摩擦磨损性能进行了研究,探讨了MoS2、石墨及纳米SiC的协同效应。认为纳米SiC的加入大大提高了复合材料的承载能力,石墨、MoS2的加入减少PTFE复合材料的摩擦因数。利用扫描电子显微镜(SEM)对PTFE复合材料的摩擦面进行了观察。结果表明:实验中5%nano-SiC和3%MoS2填充PTFE复合材料的摩擦磨损性能最好,且在高载荷下的摩擦磨损性能尤为突出,具有一定的应用价值。     

Improvements in tribological properties of polyoxymethylene by aramid short fiber and polytetrafluoroethylene

In order to improve tribological properties of polyoxymethylene (POM), the effects of aramid short fibers (ASF) and polytetrafluoroethylene (PTFE) solid lubricants, as two classes of additives, were studied. The appropriate composites of the polymer and the additives were prepared by melt mixing process. Distribution of additives in the polymer matrix was characterized by scanning electron microscopy (SEM). Mechanical properties in tension such as modulus of elasticity, yield stress, and stress-at-break as well as the fracture energy in impact test were studied to explore friction and wear mechanisms of the composites against a smooth steel surface. Tribological measurements showed that both additives reduce friction and wear of the POM. However, both additives reduced fracture energy of POM in impact test, which dismisses the role of abrasive mechanism of wear under applied conditions. On the other hand, tensile results showed that addition of ASF mechanically reinforces POM, while PTFE degrades mechanical properties of this polymer, especially yield stress. Considering the role of yield stress in the adhesive mechanism of friction and wear, this property was used to define tribological behavior of samples. Since ASF induces mechanical stiffening to POM, increase in yield stress improves tribological properties. However, PTFE introduces transfer films at the interface, thus reduction of yield stress is in favor of tribological properties of this composite. Finally, it is shown that frictional heating and contact temperature rise has a significant degrading effect on wear resistance.     

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     

纳米氮化铝填充聚四氟乙烯复合材料的性能研究

采用高速混合、冷压烧结成型的方法制备了聚四氟乙烯/纳米氮化铝（PTFE/nano AlN）复合材料,考察了nano AlN含量对复合材料结晶性能、力学性能与摩擦性能的影响,并采用扫描电子显微镜对样品磨损表面进行分析。结果表明：随着nano AlN含量的增加,复合材料的结晶度呈现先增大后降低的趋势;nano AlN可显著提高复合材料的力学性能与耐磨损性能,当其含量为4 %时,耐磨损性能与纯PTFE相比提高了2个数量级。     

Friction and wear characteristics of ceramic particle filled polytetrafluoroethylene composites under oil-lubricated conditions

Five kinds of polytetrafluoroethylene (PTFE)-based composites were prepared: PTFE, PTFE + 30 vol % SiC, PTFE + 30 vol % Si₃N₄, PTFE + 30 vol % BN, and PTFE + 30 vol % B₂O₃. The friction and wear properties of these ceramic particle filled PTFE composites sliding against GCr15 bearing steel under both dry and liquid paraffin lubricated conditions were studied by using an MHK-500 ring-block wear tester. The worn surfaces and the transfer films formed on the surface of the GCr15 bearing steel of these PTFE composites were investigated by using a scanning electron microscope (SEM)and an optical microscope, respectively. The experimental results show that the ceramic particles of SiC, Si₃N₄, BN, and B₂O₃ can greatly reduce the wear of the PTFE composites; the wear-reducing action of Si₃N₄ is the most effective, that of SiC is the next most effective, then the BN, and that of B₂O₃ is the worst. We found that B₂O₃ reduces the friction coefficient of the PTFE composite but SiC, Si₃N₄, and BN increase the friction coefficients of the PTFE composites. However, the friction and wear properties of the ceramic particle filled PTFE composites can be greatly improved by lubrication with liquid paraffin, and the friction coefficients of the PTFE composites can be decreased by 1 order of magnitude. Under lubrication of liquid paraffin the friction coefficients of these ceramic particle filled PTFE composites decrease with an increase of load, but the wear of the PTFE composites increases with a load increase. The variations of the friction coefficients with load for these ceramic particle filled PTFE composites under lubrication of liquid paraffin can be properly described by the relationship between the friction coefficient (μ) and the simplified Sommerfeld variable N/P as given here. The investigations of the frictional surfaces show that the ceramic particles SiC, Si₃N₄, BN, and B₂O₃ enhance the adhesion of the transfer films of the PTFE composites to the surface of GCr15 bearing steel, so they greatly reduce the wear of the PTFE composites. However, the transfer of the PTFE composites onto the surface of the GCr15 bearing steel can be greatly reduced by lubrication with liquid paraffin, but the transfer still takes place. Meanwhile, the interactions between the liquid paraffin and the PTFE composites, especially the absorption of liquid paraffin into the surface layers of the PTFE composites, create some cracks on the worn surfaces of the ceramic particle filled PTFE composites; the creation and development of these cracks reduces the load-supporting capacity of the PTFE composites. This leads to the deterioration of the friction and wear properties of the PTFE composites under higher loads in liquid paraffin lubrication. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2611–2619, 1999     

Impact of fillers and counterface topography on wear behavior of PTFE polymers for ultrasonic motor

Aimed to study the effects of reinforcing or functional fillers on mechanical and tribological properties of PTFE‐based friction materials of ultrasonic motor, carbon fibers reinforced PTFE composites modified with different functional fillers with differences in dimension, size, and hardness are fabricated. The tribological performances of PTFE‐based friction materials are comparatively investigated under different sliding velocities and normal loads on different surface morphologies, respectively. The experimental results reveal that nano‐SiO₂ shows excellent performance in improving friction stabilities and wear resistance in different operating conditions. It is believed the silica‐based tribofilms, higher deformation resistance, and bearing capacity play a key role in improving friction stabilities. Furthermore, the results also show that the surface topography plays an important role in wear properties. The lower wear rate (sliding against with the disordered surface) is believed to be attributed to wear debris easy‐store characteristic of the topography, which promotes transfer films formation and decreases the wear rate effectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44835.     

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