炭纤维增强聚醚醚酮复合材料在水润滑下的摩擦学行为

考察了炭纤维及PTFE增强PEEK复合材料在干摩擦和水润滑下的摩擦学性能,并研究了该复合材料在两种条件下的磨损机理.结果表明,干摩擦下复合材料的摩擦系数和磨损率随负荷的增加不断减小;水润滑下复合材料的摩擦系数随负荷的变化不大,磨损率随负荷的增加而增大.干摩擦下,复合材料的磨损以粘着磨损和磨粒磨损为主.水润滑条件下,磨损表面比较光滑,仅有微切削的痕迹,磨损方式以轻微磨粒磨损为主.干摩擦条件下,摩擦对偶表面仅有轻微的犁沟形成,表面形成一层薄而均匀且结合紧密的转移膜.水润滑下,对偶表面犁沟较深,犁削作用明显,转移膜的形成被明显抑制.水的冷却作用使得向摩擦对偶的粘着转移明显减轻,同时由于摩擦表面吸附水膜的边界润滑作用,显著改善复合材料的摩擦磨损性能.     

氟化钙和炭纤维混杂增强尼龙复合材料的摩擦学性能和磨损机理

以注塑成型法制备了无机填料氟化钙(CaF2)和炭纤维增强尼龙1010复合材料,采用MM-200型磨损试验机考察了复合材料的摩擦磨损性能。研究结果表明,CaF2和炭纤维的复合添入可显著改善尼龙复合材料的摩擦学性能。其中30％CF～10％CaF2-Nylon的耐磨性能比30％CF-Nylon提高近5倍,而摩擦系数降低了约1／4．CaF2和CF增强尼龙复合材料在摩擦过程中发生了协同效应,CF-CaF2-Nylon在对偶钢环表面上生成富含钙元素的连续薄转移膜。提高了转移膜和对偶间的结合强度以及复合材料耐磨性能．     

铸型尼龙及其复合材料的摩擦学性能和晶型转变

利用 MM- 2 0 0摩擦磨损试验机研究了在干摩擦和水润滑条件下铸型尼龙 (MC尼龙 )及其复合材料的摩擦磨损性能 ,并利用红外光谱分析了材料在不同磨损条件下发生的物理化学变化。研究结果表明 ,在干摩擦条件下 ,当载荷与速度的积 (pv值 )小于 84 N.m/s时玻璃纤维增强 MC尼龙复合材料(GF/MC)的摩擦系数和磨损率都比 MC尼龙低 ;当 pv值大于 84 N.m/s时 ,GF/MC的摩擦系数略高于MC尼龙 ,而磨损率则远大于 MC尼龙 ,随 pv值的改变 ,磨损机理发生了变化。在水润滑条件下二者的摩擦系数降低 ,GF/MC的耐磨性比纯基体显著提高。光谱分析表明 ,MC尼龙及其复合材料在摩擦过程中会发生晶型转变 ,在干摩擦后 α晶型减少 ,γ晶型增多 ,在水润滑后 α晶型增多 ,而 γ晶型减少     

纳米SiO2对聚丙烯酸酯复合涂层在水润滑下摩擦学性能的影响

考察了纳米SiO₂对聚丙烯酸酯复合涂层在水润滑下摩擦磨损性能的影响。利用FTIR分析纳米SiO₂与聚丙烯酸酯的界面结合;利用SEM观察复合涂层磨损表面,并结合FTIR和摩擦磨损实验分析其磨损机理。结果表明:水润滑时,聚丙烯酸酯在摩擦过程中会发生摩擦化学反应,引起涂层摩擦腐蚀磨损;而纳米SiO₂能与聚丙烯酸酯以化学键的形式结合,它的加入有助于摩擦界面在水介质中形成具有较好减摩作用的表面膜和水分子膜,提高聚丙烯酸酯复合涂层的耐磨性。在水润滑下,当纳米SiO₂的含量较低时,涂层表面的磨损形式为摩擦腐蚀磨损和磨粒磨损;当纳米SiO₂的含量达到5wt% 时,涂层表面形成完整的表面膜和水分子膜,此时涂层具有良好的摩擦学性能。      

PTFE/金属自润滑复合材料的磨损性能研究

用MM-200磨损试验机对纯PTFE板料、3层复合材料(DU)及钉板型复合材料的工作层在干摩擦定载荷条件下的磨损性能进行了研究;用SEM对磨损试样表面和磨屑形貌进行观察和分析.结果表明:铜和PTFE的复合能提高PTFE的耐磨性并改变其磨屑的形成机理;铜钉板取代传统的平钢板,不仅提高了材料的承载能力,也大大提高了材料的耐磨性能;在干摩擦条件下,纯PTFE板料主要发生粘着磨损和微凸体刨切,3层复合材料主要是磨粒磨损,钉板型复合材料的磨损机理是粘着磨损和磨粒磨损共同作用.     

化学共沉积Ni-P-(IF-WS2)复合镀层的制备及其摩擦磨损性能

用化学共沉积技术制备了Ni-P-(IF-WS2)复合镀层,利用销-盘式磨损试验机在干摩擦、滑动速度0.0623 m/s、接触载荷20～160 N条件下评价了Ni-P-(IF-WS2)复合镀层的摩擦磨损性能.研究结果表明Ni-P-(IFWS2)复合镀层比Ni-P镀层具有更高的耐磨性能和更低的摩擦系数.分析了无机类富勒烯纳米材料改善镀层摩擦学性能的机理.     

锡青铜表面超疏水薄膜的制备及其水润滑减摩性能

为了改善锡青铜在水润滑条件下的摩擦性能,在其表面以1％氟硅烷乙醇溶液制备了超疏水薄膜.通过扫描电镜(SEM)观察了超疏水薄膜的表面形貌,测量了其接触角;在CETRUMT-2球-盘摩擦磨损试验机上考察了超疏水薄膜水润滑下的减摩性能.结果表明:锡青铜表面刻蚀并成膜后形成了粗糙的微纳复合结构,刻蚀40 min表面接触角可达151.1°,具备超疏水性能;超疏水薄膜在水润滑下具有较低的摩擦系数,可有效降低摩擦副的磨损.     

短碳纤维增强铜基复合材料的摩擦磨损性能研究

采用冷压烧结工艺制备了短碳纤维增强铜基复合材料,考察了该复合材料的干摩擦磨损性能.讨论了短碳纤维含量、载荷、转速等对复合材料摩擦性能的影响.结果表明:复合材料的耐磨性能明显优于基体材料;随着碳纤维含量的增加复合材料的耐磨性能进一步提高;随载荷和转速的提高,摩擦系数和磨损量也随之增加;复合材料由纯铜的粘着磨损转变为剥层磨损,并均伴有一定的氧化磨损.     

三维编织复合材料在润滑条件下的摩擦性能

利用树脂传递模塑(RTM)工艺制备了三维编织炭纤维/环氧(C3D/EP)复合材料.采用MM-200型摩擦磨损试验机研究了该材料润滑条件下的摩擦磨损性能,探讨了载荷及滑动速度等外界因素的影响;并采用XL30 ESEM电子显微镜观察磨损表面形貌,分析了其磨损机理.结果表明,润滑条件下复合材料的摩擦磨损性能远优于干摩擦,且磨合期较短;随着载荷的增加,复合材料的摩擦系数和比磨损率降低,但滑动速度对摩擦磨损性能的影响很小;润滑条件下的磨损机理主要是磨粒磨损.     

纤维及晶须增强PTFE复合材料的摩擦磨损性能研究

利用MHK－500型环－块磨损试验机,对炭纤维,玻璃纤维及钛酸钾（K2Ti6O13)晶须增强聚四氟乙烯（PTFE）复合材料在干摩擦条件下与GCr15轴承钢对磨时的摩擦学性能进行了较为系统的研究,并利用扫描电子显微镜（SEM）和光学显微镜对其磨屑和摩擦表面进行了观察。结果表明,炭纤维,玻璃纤维及K2Ti6O13晶须虽增大了PTFE的摩擦系数,但均可将PTFE的磨损量降低2个数量级,其中玻璃纤维的减磨效果最好,K2TiO13晶须的减磨效果最差,由于K2TiO13晶须的承载能力较差,致使K2Ti6O13晶须增强PTFE复合材料的磨损表面发生了明显的挤压变形,因而该复合材料具有较高的摩擦和磨损。     

碳纤维增强尼龙1010的力学性能及其对摩擦磨损的影响

用碳纤维填充尼龙1010制备了碳纤维增强尼龙复合材料,并对碳纤维增强尼龙复合材料的力学性能和摩擦学性能进行了实验研究。力学实验结果表明:碳纤维增强使尼龙复合材料的拉伸强度、表面硬度增大,碳纤维增强尼龙材料的拉伸强度在20%碳纤维含量时达到最大值;碳纤维表面处理对尼龙复合材料的拉伸强度有很大影响,碳纤维表面氧化处理提高了碳纤维增强尼龙复合材料的拉伸强度。摩擦磨损实验表明:碳纤维增强尼龙复合材料的摩擦系数和磨损率与其拉伸强度和硬度有密切关系。随着拉伸强度和硬度的提高,尼龙复合材料摩擦系数和磨损率降低;摩擦系数和磨损率与拉伸强度具有反比关系,与材料硬度具有二次方程关系,与碳纤维填充量之间存在负指数变化规律。      

SiC 和Gr 颗粒混杂增强Al 基复合材料的摩擦磨损特性的研究

比较了SiC 和Gr 颗粒混杂增强Al 基复合材料的干摩擦磨损行为, 并与单一SiC_P 和单一G_rP 增强Al 基复合材料的相应行为进行了比较。结果表明, 在低载荷(< 30 N ) 时, SiC_P 和G_rP 能协调作用, 使混杂复合材料的摩擦系数和磨损率均比单一SiC_P 和G_rP 增强复合材料低。在较高载荷(30～ 120 N ) 时, 混杂复合材料磨损以剥层磨损机制为主, 摩擦系数比单一SiC_P 增强复合材料低, 磨损率比单一G_rP 增强复合材料低得多, 比单一SiC_P 增强复合材料高。混杂复合材料对偶件的磨损比单一SiC_P 增强复合材料低得多。      

Hybrid effect of nanoparticles with carbon fibers on the mechanical and wear properties of polymer composites

Polyetheretherketone (PEEK) composites reinforced with carbon fibers (CFs) and nano-ZrO₂ particles were prepared by incorporating nanoparticles into PEEK/CF composites via twin-screw extrusion. The effects of nanoparticles on the mechanical and wear properties of the PEEK/CF composites were studied. The results showed that the incorporation of nano-ZrO₂ particles with carbon fiber could effectively enhance the tensile properties of the composites. The tensile strength and Young’s modulus of the composites increased with the increasing nano-ZrO₂ content. The enhancement effect of the particle was more significant in the hybrid reinforced composites. The compounding of the two fillers also remarkably improved the wear resistance of the composites under water condition especially under high pressures. It was revealed that the excellent wear resistance of the PEEK/CF/ZrO₂ composites was due to a synergy effect between the nano-ZrO₂ particles and CF. CF carried the majority of load during sliding process and prevented severe wear to the matrix. The incorporation of nano-ZrO₂ effectively inhibited the CF failures through reducing the stress concentration on the carbon fibers interface and the shear stress between two sliding surfaces. It was also indicated that the wear rates of the hybrid composites decreased with the increasing applied load and sliding distance under water lubrication. And low friction coefficient and low wear rate could be achieved at high sliding velocity.     

Synergism of several carbon series additions on the microstructures and tribological behaviors of polyimide-based composites under sea water lubrication

The effects of several carbon series additions including graphite (Gr), carbon fiber (CF) and carbon nanotube (CNT) on the microstructures and tribological behaviors of polyimide-based (PI-based) composites under sea water lubrication were investigated systematically. Results showed that the incorporation of any filler improved the wear resistance of polyimide (PI) under sea water lubrication, but did not decrease the friction coefficient. Especially the combined incorporation of 10%Gr, 10%CF and 5%CNT (in volume) was the most effective in improving the anti-wear properties of PI. This suggested that there existed a synergetic effect among the three carbon series additions on improving the wear resistance of PI. During the friction and wear process, the carbon additions played different roles in improving the wear resistance of PI-based composites. CF with high compressive strength can carry the main load applied on the sliding surfaces to inhibit the wear of PI matrix. CNT can decrease the stress concentration around CF and further protect CF from being broken. Gr in the form of much thinner layer can not only improve the loading capacity, but also play the same role of CNT to avoid CF carrying too much load. More importantly, Gr, CF and CNT worked synergistically to condense the microstructure of PI-based composite and ameliorate the interfacial combination between all fillers and PI matrix, which well explained why the PI–10%Gr–10%CF–5%CNT composite had excellent tribological properties, even under heavy load or high sliding speed.     

Synergism of carbon fiber and polyimide in polytetrafluoroethylene-based composites: Friction and wear behavior under sea water lubrication

Polytetrafluoroethylene-based (PTFE-based) composites reinforced simultaneously with carbon fiber (CF) and polyimide (PI) of different volume fractions were prepared. The microstructure and phase composition of as-prepared PTFE-based composites were analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Besides, their friction and wear behavior under sea water lubrication was evaluated in relation to the synergistic effect between CF and PI using a ring-on-block test rig, and their worn surfaces were also analyzed using SEM. Results showed that the incorporation of PI induced loosening of the microstructure of PTFE but increased the wear resistance. Contrary to the above, the incorporation of CF led to increased compactness of PTFE, and the compactness as well as wear resistance of the PTFE-based composites increased with the increase of CF content. More importantly, the simultaneous incorporation of PI and CF at a proper volume fraction led to drastically reduced wear rate of PTFE under sea water lubrication. This implies that there exists synergistic friction-reducing and wear-resistant effect between PI and CF. As a result, the PTFE-based composite containing 5% PI (volume fraction) and 15% CF had the best wear resistance, showing promising application in ocean environment.     

The friction and wear properties of carbon nanotubes/graphite/carbon fabric reinforced phenolic polymer composites

In this paper, either graphite (Gr) or carbon nanotubes (CNTs), or both of them were incorporated into carbon fabric reinforced phenolic (CFRP) composites, preparing by a dip-coating and heat molding process, the tribological properties of the resulting composites were investigated using a block-on-ring arrangement. The worn surfaces were observed by scanning electron microscope to understand the mechanism. Experimental results showed that the optimal Gr was more beneficial than CNTs in improving the tribological properties of the CFRP composites when they were singly incorporated. It is well worth noting that the friction and wear behavior of the CNTs-filled CFRP composites were improved further when Gr was added, indicating that there is a synergistic effect between them. Tribological tests under different sliding conditions revealed that the Gr and CNTs-filled CFRP composites seemed to be the most suitable for tribological applications under higher sliding speed and load, and oil lubrication.     

Effect of surface oxidation treatment on the tribological performance of carbon fiber reinforced polyimide composites

The effect of ozone surface treatment of carbon fibers (CF) on the tensile strength and tribological properties of carbon fiber reinforced polyimide (CF/PI) composite was investigated. Experimental results revealed that the tensile strength of ozone and air oxidation treated CF reinforced PI composite was improved compared with that of untreated composite. Compared with the untreated and air‐oxidated CF/PI composite, the ozone treated composite had the lowest friction coefficient and specific wear rate under given applied load and reciprocating sliding frequency. Ozone treatment effectively improved the interfacial adhesion between CF and PI. The strong interfacial adhesion of the composite made CF not easy to detach from the PI matrix, and prevented the rubbing‐off of PI, accordingly improved the friction and wear properties of the composite.     

Friction and wear behavior of carbon nanotubes reinforced polyamide 6 composites under dry sliding and water lubricated condition

The friction and wear behavior of carbon nanotube reinforced polyamide 6 (PA6/CNT) composites under dry sliding and water lubricated condition was comparatively investigated using a pin-on-disc wear tester at different normal loads. The morphologies of the worn surfaces and counterfaces of the composites were also observed with scanning electron microscopy (SEM). The results showed that CNTs could improve the wear resistance and reduce the friction coefficient of PA6 considerably under both sliding conditions, due to the effective reinforcing and self-lubricating effects of CNTs on the PA6 matrix. The composites exhibited lower friction coefficient and higher wear rate under water lubricated condition than under dry sliding. Although the cooling and boundary lubrication effect of the water contributed to reduce the friction coefficient of the composites, the adsorbed water lowered the strength of the composites and also inhibited the formation of transfer layers on the counterfaces resulting in less wear resistance. With the increasing normal loads, the friction coefficient of the composites increased under the dry sliding and decreased under the water lubricated condition, owing to inconsistent influences of shear strength and real contact areas. The specific wear rate of the composites increased under both sliding conditions.