聚四氟乙烯与超细高岭土填充聚甲醛复合材料的摩擦学性能

用聚四氟乙烯(PTFE)和超细高岭土填充聚甲醛(POM),采用热模压成型工艺制备出四种不同成分的试样,在往复式滑动摩擦试验机上进行摩擦磨损试验,并对磨损表面形貌进行了分析.结果表明:只填充PTFE的复合材料的摩擦因数和磨损率较纯POM均有较大幅度的下降,7.5%高岭土与20%PTFE复合填充的复合材料摩擦因数最小,耐磨性最好;纯POM的磨损机制是粘着磨损和磨粒磨损,POM复合材料的磨损机制以粘着磨损为主.     

PTFE、石墨与玻璃纤维填充聚甲醛的摩擦磨损特性研究

用聚四氟乙烯(PTFE)、玻璃纤维(GF)和石墨填充聚甲醛(POM),采用热模压成型制备出4种复合材料。在往复式滑动摩擦试验机上进行摩擦磨损实验。实验条件为正压力5.8 MPa,往复频率1 Hz,对摩面粗糙度Ra0.8μm。结果表明:经填充的POM复合材料的摩擦因数和比磨损率均有不同程度的降低,其中POM 20%(质量分数)PTFE的摩擦因数最低,POM 20%PTFE 10%GF的耐磨性最好。扫描电镜分析表明POM材料的磨损机制以粘着磨损为主。     

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。     

硫酸钙晶须填充PTFE复合材料的摩擦学性能研究

用硫酸钙晶须(CSW )填充改性聚四氟乙烯(MVE),采用模压成型工艺制备不同硫酸钙晶须含量的PTFE/CSW复合材料;利用摩擦磨损试验机研究硫酸钙晶须对PTFE/CSW复合材料摩擦学性能的影响,利用扫描电子显微镜对PM复合材料的磨损表面进行微观分析.结果表明:填充硫酸钙晶须提高PTFE复合材料的耐磨损性能,但复合材料的摩擦因数略高于纯PTFE;纯PTFE的磨损机制为黏着磨损,而PTFE/CSW复合材料的磨损机制为轻微磨粒磨损和黏着磨损共同作用.当硫酸钙晶须质量分数大于10%时,PTFE/CSW复合材料的磨损机制逐渐转变为严重的磨粒磨损.     

碳材料填充PTFE复合材料摩擦磨损性能

利用 MM-200 型磨损试验机考察了石墨、碳纤维、硬碳和软碳填充 PTFE 复合材料的摩擦磨损性能,采用扫描电子显微镜观察分析磨损表面形貌及磨损机制.结果表明,碳材料可以不同程度地提高 PTFE 的耐磨性,它们对PT-FE 耐磨性的提高程度各不相同,其中以硬碳填充 PTFE 复合材料的磨损质量损失最小,石墨填充 PTFE 复合材料的磨损质量损失较大;不同填充材料对 PTFE 摩擦因数的影响各不相同,其中石墨填充 PTFE 的摩擦因数较小.石墨、软碳填允复合材料磨损机制以粘着磨损为主,硬碳、碳纤维复合材料,则表现为粘着磨损和磨粒磨损.     

纳米粒子和聚四氟乙烯填充UHMWPE复合材料的摩擦磨损性能研究

以纳米氧化锌(ZnO)和纳米蒙脱土(MMT)及聚四氟乙烯(PTFE)作为复合填料,通过热压成型工艺制备了纳米ZnO-MMT及PTFE填充超高分子量聚乙烯(UHMWPE)复合材料,采用销-盘式摩擦磨损试验机考察了纳米粒子对复合材料摩擦磨损性能的影响,用扫描电子显微镜观察了复合材料磨损表面形貌。结果表明当PTFE和MMT的填充量均保持为质量分数6%,填充纳米ZnO质量分数为4%~6%时的复合材料可获得较好的摩擦磨损性能,与不含纳米ZnO的复合材料相比,其摩擦因数最低下降了11.1%,而磨损率下降了83.3%。当复合填料中纳米ZnO含量较低时,复合材料的磨损机制主要表现为不同程度的粘着磨损,但当复合填料中纳米ZnO含量较高时,复合材料的磨损机制主要表现不同程度的粘着磨损和磨粒磨损,同时其复合材料的摩擦磨损性能出现了恶化现象。     

纳米高岭土和石墨填充PTFE复合材料摩擦磨损性能

采用模压法制备石墨和纳米高岭土填充的聚四氟乙烯(PTFE)复合材料,在往复式滑动摩擦磨损试验机上测试了其的干滑动摩擦磨损性能,试验机往复频率为1.0 Hz.用扫描电镜观测和分析试样的磨损表面.结果表明:石墨和纳米高岭土共同填充的PTFE,在改善其耐磨性的同时,又保持了低的摩擦因数,其中含10%高岭土和5%石墨的PTFE复合材料表现最佳,稳定阶段的摩擦因数保持在0.11左右,耐磨性比纯PTFE提高了大约90倍.     

有机填料填充聚四氟乙烯复合材料摩擦学及力学性能

采用共混-冷压-烧结-整形的工艺制备有机物填充聚四氟乙烯(PTFE)复合材料,考察相同含量的不同有机填料对PTFE复合材料力学性能和摩擦学性能的影响。结果发现,加入有机填料后,复合材料的拉伸强度降低,但硬度和压缩强度均提高;有机填料有效地改善了PTFE复合材料的摩擦学性能,其中,质量分数15%聚苯酯填充的PTFE复合材料减摩效果最好,质量分数15%聚酰亚胺填充的PTFE复合材料的耐磨损性能最优。相比之下,质量分数15%芳纶填充的PTFE复合材料摩擦磨损性能及力学性能最好,其耐磨损性能较纯PTFE提高了近400倍,而摩擦因数仅为纯PTFE的84%。其原因在于芳纶的加入有效地改变了摩擦机制,能形成均匀连续的转移膜,进而降低了磨损。     

PTFE与纳米高岭土填充PPS复合材料的摩擦磨损性能研究

通过模压的方法制备了聚四氟乙烯(PTFE)和纳米高岭土填充的聚苯硫醚(PPS)复合材料。摩擦磨损实验在往复式滑动摩擦试验机上完成进行,对摩面为硬度值HRC 38、表面粗糙度Ra0.8μm的45#钢。用扫描电镜观察了试样磨损表面形貌。实验结果表明:填料的加入降低了PPS的摩擦因数和磨损率,且PTFE和纳米高岭土共同填充的PPS复合材料比单一PTFE填充的PPS复合材料具有更好的摩擦磨损性能;其中试样PPS 15%PTFE 15%(质量分数)纳米高岭土具有最低的稳定摩擦因数0.20~0.23和最小的磨损率1.9×10-6mm3/(N.m)。PTFE和纳米高岭土的加入使PPS的主要磨损方式由粘着磨损转变为磨粒磨损。     

纳米碳黑与纳米石墨填充PTFE复合材料摩擦磨损性能比较研究

用M-2000摩擦磨损试验机对纳米碳黑和石墨填充PTFE复合材料进行了摩擦磨损性能研究,用扫描电子显微镜(SEM)对磨损表面进行观察.结果表明:2种碳纳米能够提高PTFE复合材料的耐磨性,其中纳米碳黑填充效果最佳.纳米碳黑和纳米石墨2种碳纳米的最佳添加量分别为7%和5%(质量分数).纳米石墨可以减小PTFE复合材料的摩擦因数,而纳米碳黑使得PTFE复合材料的摩擦因数增大,且含量越高,复合材料摩擦因数增幅越大.结晶型纳米石墨与PTFE基体的相容性较差,而无定形纳米碳黑与PTFE基体的相容性较好.     

Friction and wear of blended polyoxymethylene sliding against coated steel plates

Measurements were made of the dynamic friction coefficients and specific wear rates of several thermoplastics rubbing against relatively soft coatings on steel plates. Polyoxymethylene (POM)-based composites were investigated using reciprocating, line contact tests against two types of corrosion-protected steel plates (electro-deposited cathodic epoxy layers, called “E-coatings”, and galvanised plates). In addition to virgin POM, composites containing glass fibres, polytetrafluoroethylene (PTFE) fibres, PTFE micro-powder, and high-viscosity silicon oil were investigated. Sliding speeds ranged from 0.05 to 0.3 m/s, and normal loads ranged from 5 to 30 N. The E-coating failed at high loads and velocities. The beneficial effects of lubricating additives in tests with uncoated steel counterfaces were also observed with the coated steel surfaces. POM with glass fibre additives was found to be more abrasive than the base material. The considered non-conformal contact produced similar friction and wear trends than those obtained for the conformal contact.     

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.     

Friction and wear properties of metal powder filled PTFE composites under oil lubricated conditions

Four kinds of polytetrafluoroethylene (PTFE)-based composite, pure PTFE, PTFE+30vol.%Cu, PTFE+30vol.%Pb and PTFE+30vol.%Ni composite, were prepared. The friction and wear properties of these metal powder filled PTFE composites sliding against GCr15 bearing steel under both dry and lubricated conditions were studied using an MHK-500 ring-block wear tester. The worn surfaces of the PTFE composites and the transfer films formed on the surface of GCr15 bearing steel were examined using scanning electron microscopy (SEM) and optical microscopy respectively. Experimental results show that the friction and wear properties of the PTFE composites can be greatly improved by liquid paraffin lubrication. The wear of these PTFE composites can be decreased by at least 1 to 2 orders of magnitude compared with that under dry friction conditions, while the friction coefficients can be decreased by 1 order of magnitude, SEM and optical microscopy investigations of the rubbing surfaces show that metal fillers of Cu, Pb and Ni not only raise the load carrying capacity of the PTFE composites, but also promote transfer of the PTFE composites onto the counterfaces, so they greatly reduce the wear of the PTFE composites. However, the transfer of these PTFE composites onto the counterfaces can be greatly reduced by liquid paraffin lubrication, but transfer still takes place.     

Tribological Behavior of Carbon-Nanotube-Filled PTFE Composites

Carbon nanotube/polytetrafluoroethylene (CNT/PTFE) composites with different volume fractions were prepared and their friction and wear properties were investigated using a ring-on-block under dry conditions. It was found that CNTs signifi-cantly increased the wear resistance of PTFE composites and decreased their coefficient of friction. PTFE composites with 15–20 vol.% CNTs exhibited very high wear resistance. The significant improvements in the tribological properties of CNT/PTFE composites are attributed to the super-strong mechanical properties and the very high aspect ratio of CNTs. The CNTs greatly reinforce the structure of the PTFE-based composites and thereby greatly reduce the adhesive and plough wear of CNT/PTFE composites. The CNTs are released from the composite during sliding and transferred to the interface of the friction couples. They thus serve as spacers, preventing direct contact between the mating surfaces and thereby reducing both wear rate and friction coefficient.     

聚四氟乙烯及其石墨和MoS2填充复合材料的摩擦学性能研究

利用往复式摩擦磨损实验机,对聚四氟乙烯(PTFE)及石墨和MoS2填充的PTFE复合材料的摩擦磨损性能进行了实验,考察了载荷、速度以及对摩时间的影响,并利用光学显微镜对PTFE复合材料的摩擦磨损表面进行了观察。结果表明,填加了石墨和MoS2的PTFE,由于石墨和MoS2一方面起到了润滑作用,另一方面阻止了PTFE带状大面积破坏,因而使得PTFE的摩擦因数降低,耐磨性提高。加入石墨和MoS2后PTFE的磨损机制由以犁沟效应和粘着磨损为主变为以磨粒磨损为主。     

剑麻纤维和低密度聚乙烯填充聚甲醛复合材料的摩擦磨损性能

通过双螺杆挤出熔融共混的方法制备剑麻纤维(SF)和低密度聚乙烯(LDPE)共同填充的聚甲醛复合材料,在HT-500型高温摩擦磨损试验机上考察其干滑动摩擦条件下的摩擦磨损性能,并通过扫描电子显微镜(SEM)观察其磨损表面形貌,分析磨损机制。结果表明:添加适量的LDPE能显著降低POM的摩擦因数和磨损率,当LDPE质量分数为5%时,复合材料的摩擦因数下降21.7%,磨损率降低10%;随SF质量分数的增加,POM/5%LDPE/SF复合材料的摩擦因数和磨损率呈现先增大后减小再增大的趋势,当SF质量分数为5%时,复合材料摩擦磨损性能优异,在转速为1 120 r/m in,恒定载荷为8 N的实验条件下,其稳定摩擦因数为0.16,磨损率为1.61×10-6mm3/(N.m)。纯POM磨损方式以黏着磨损为主,POM/5%LDPE/SF复合材料以疲劳磨损为主,伴随有转移膜的剥落。     

碳纳米管增强PTFE复合材料摩擦磨损性能研究

以不同含量的CNTs(碳纳米管)为填料制备了PTFE基复合材料,测量其硬度,在M-2000型摩擦磨损试验机上研究其摩擦磨损行为。结果表明,CNTs能提高PTFE的硬度,CNTs/PTFE复合材料的耐磨性能明显优于纯PT-FE,当CNTs的质量分数为3%时,复合材料的耐磨性能大幅度提高。其摩擦因数随着CNTs含量的增加而加大,当CNTs的质量分数为1%时,摩擦因数随载荷的增加而减少,CNTs的质量分数为3%和5%时,摩擦因数随载荷的增加而增大。SEM观察发现:纯PTFE的断面上分布着大量的带状结构,而填充CNTs后,摩擦表面较平整光滑,表明CNTs作为填料可有效地抑制PTFE的犁削和粘着磨损。     

Friction and wear characteristics of lead and its compounds filled polytetrafluoroethylene composites under oil lubricated conditions

The friction and wear properties of Pb, PbO, Pb₃O₄, or PbS filled polytetrafluoroethylene (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 of these PTFE composites formed on the surface of GCr15 bearing steel were then investigated by using a scanning electron microscope (SEM) and an optical microscope, respectively. Experimental results show that filling Pb, PbO, Pb₃O₄ or PbS to PTFE can greatly reduce the wear of the PTFE composites, but the wear reducing action of Pb₃O₄ is the most effective. Meanwhile, PbS increases the friction coefficient of the PTFE composite, but Pb and Pb₃O₄ reduce the friction coefficients of the PTFE composites. However, the friction and wear properties of lead or its compounds filled PTFE composites can be greatly improved by lubrication with liquid paraffin, and the friction coefficients of the PTFE composites can be decreased by one order of magnitude. Optical microscope investigation of transfer films shows that Pb, PbO, Pb₃O₄ and PbS enhance the adhesion of the transfer films 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 GCr15 bearing steel can be greatly reduced by lubrication with liquid paraffin, but the transfer still takes place. SEM examination of worn surfaces shows that the interaction between liquid paraffin and the PTFE composites creates some cracks on the worn surfaces of the PTFE composites; the creation and development of the cracks reduces the load-carrying capacity of the PTFE composites, and this leads to deterioration of the friction and wear properties of the PTFE composites filled with lead or its compounds under higher loads in liquid paraffin lubrication.     

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.