仿生多孔润滑耐磨CF/PTFE/PEEK复合材料的设计及其摩擦学性能

采用模压-滤取和高温真空熔渍工艺制备了自身发汗式润滑耐磨多孔CF/PTFE/PEEK复合材料。考察了造孔剂(NaCl)、PTFE的含量及炭纤维层间间距对多孔PEEK复合材料结构和摩擦学性能的影响。结果表明,当PTFE含量为20%(质量分数,下同)、NaCl为30%、炭纤维层间间距为0.4mm所得多孔CF/PTFE/PEEK复合材料摩擦因数和磨损率最低,200N下摩擦因数、磨损率分别为0.0192,3.47×10-16 m3/Nm,较经典CF/PEEK复合材料摩擦因数降低了9倍,耐磨性提高了25倍。原因在于复合材料中PTFE能形成连续的转移膜,降低了材料摩擦因数;NaCl形成的多孔结构能储存住一定润滑油脂,摩擦过程中在载荷和温度的作用下能形成稳定润滑油膜,明显降低了材料磨损量;炭纤维布起到支撑骨架作用,并协同PTFE,NaCl提高多孔PEEK复合材料摩擦磨损性能。     

纳微多级孔ACF/PTFE/PEEK复合材料的制备及发汗式减摩耐磨性能

采用模压-滤取和高温真空熔渍工艺及纳微多尺度协同设计制备了自身发汗式多级孔活性炭纤维(ACF)/聚四氟乙烯(PTFE)/聚醚醚酮(PEEK)复合材料。考察了ACF、微米级造孔剂NaCl含量及载荷对其摩擦学性能的影响。结果表明,当介孔ACF总质量分数为8%、NaCl总质量分数为30%所得多级孔ACF/PTFE/PEEK复合材料摩擦系数和磨损率最低,载荷为200N时,摩擦系数、磨损率分别为0.0259、5.26×10-16m3/N·m,较经典炭纤维增强PEEK复合材料摩擦系数减少86%,耐磨性提高了16倍。研究表明,介孔ACF在材料内部形成了贯通型三维网络毛细管道,如同人体汗腺机制,使微米级孔中储存的润滑脂在载荷和温度的作用下能在摩擦面上形成较好的润滑油膜,并且ACF能起到部分骨架支撑作用,因而ACF在材料中起到很好的减摩耐磨作用。     

CaCO3晶须和PTFE对PEEK干摩擦性能的影响

用热压成型法制备CaCO3晶须和聚四氟乙烯(PTFE)填充的聚醚醚酮(PEEK)自润滑复合材料,研究了干摩擦条件下复合材料和45#钢环配副的摩擦磨损性能,并与纯PEEK进行了比较.结果表明:CaCO3晶须和PTFE明显改善了PEEK复合材料的减摩、耐磨和承载性能,其摩擦系数比纯PEEK降低约1/2,耐磨性提高27倍;摩擦稳定性显著提高,极限承载能力比纯PEEK提高1倍以上.CaCO3晶须降低了复合材料摩擦表面粘着、犁削和热变形,PTFE有助于复合材料在偶件表面形成连续、均匀的转移膜.PEEK自润滑复合材料的磨损机制主要是轻微的粘着和疲劳磨损.     

碳纤维酚醛树脂基复合材料制备及摩擦磨损性能研究

以酚醛树脂为基体,碳纤维为增强纤维,石墨和聚醚醚酮(PEEK)为固体润滑剂,通过热压成型方法制备复合材料。通过多功能立式摩擦磨损试验机对复合材料进行摩擦磨损测试,扫描电子显微镜观察复合材料的磨损表面。结果表明,石墨的加入能够降低复合材料的摩擦系数和磨损率,当加入15%(wt,质量分数)石墨的复合材料的摩擦系数为0.1,磨损率为0.37×10~(-6)g/N·m。PEEK的加入能够增加复合材料的摩擦系数,降低复合材料的磨损率,当加入10%(wt,质量分数)PEEK的复合材料表现出最好的摩擦性能,摩擦系数为0.28,磨损率为0.92×10~(-6)g/N·m。     

原位聚合法制备的聚醚醚酮/膨胀石墨复合材料及性能

以膨胀石墨(EG)负载对苯二酚后和4,4′-二氟二苯甲酮单体,采用原位亲核缩聚法制备了聚醚醚酮/膨胀石墨复合材料(PEEK/EG)。通过黏度分析法探讨了膨胀石墨对PEEK相对分子质量的影响;采用X射线衍射、差示扫描量热分析和热重分析研究了膨胀石墨对PEEK结晶性能和热性能的影响;通过扫描电镜表征了膨胀石墨在PEEK基体中的分散形态;通过摩擦测试仪研究了PEEK及PEEK/EG摩擦性能。结果表明,原位缩聚过程中引入EG不会影响PEEK晶型;EG含量为0.5%时PEEK/EG复合材料初始分解温度提高10℃,同时,EG在基体中分散效果良好。PEEK/EG-0.5%的磨损率为4.00×10-6 mm2/(N·m),远低于纯PEEK的15.80×10-6 mm2/(N·m)。     

纳米ZrO_2和聚醚醚酮填充聚四氟乙烯的摩擦学性能基于环-块摩擦模型的演变过程

用不同体积分数的纳米ZrO_2和聚醚醚酮(PEEK)颗粒填充改性聚四氟乙烯(PTFE)复合材料。使用环-块摩擦磨损试验机测试PTFE复合材料在滑动速度为2 m/s、载荷为200 N的试验条件下的摩擦学性能。获取不同阶段摩擦学性能的数据,计算出在整个试验过程中样品的瞬时磨损率。利用扫描电镜观察不同试验阶段对偶钢环表面形貌的变化图像并进行分析。利用仿真模拟软件(ABAQUS)对摩擦过程中PTFE复合材料的接触应力变化进行分析。结果表明,纳米ZrO_2和PEEK颗粒可以协同改善PTFE复合材料的摩擦学性能。特别是添加8%的纳米ZrO_2和20%的PEEK能使PTFE复合材料同时获得最佳的耐磨性(1.29×10~(-6) mm~3/Nm)和较低的摩擦系数。在摩擦试验的后期PTFE复合材料的瞬时磨损率突然急剧上升。根据瞬时磨损率、磨损表面、转移膜形貌和磨屑形态特征的变化规律,将整个磨损过程分为3个阶段(低磨损阶段、过渡磨损阶段和严重磨损阶段)。     

不同聚合物填充PTFE复合材料的摩擦学性能研究

利用机械共混,冷压成型,烧结等工艺制备了四种聚四氟乙烯复合材料,并利用MRH-3型摩擦磨损试验机考察了载荷200N,滑动速度2m/s下复合材料的摩擦磨损性能。采用JSM-6700扫描电子显微镜观察分析了转移膜形貌及磨损机理。实验结果表明,PEEK、AF、PI的加入都能有效地提高PTFE的压缩强度和压缩模量。10%PEEK/PTFE复合材料的平均摩擦系数最小,5%PI/10%PEEK/PTFE复合材料耐磨性最好,其耐磨性较纯PTFE提高了630倍。     

SiCp/Al复合材料-半金属刹车材料干摩擦磨损性能研究

采用无压浸渗法制备15%(体积分数,下同),25%,35%,45%,55%的SiC颗粒(45,63μm)增强的铝基复合材料(SiCp/Al).在M-200型环块式磨损试验机上研究了SiCp/Al复合材料、灰铸铁(HT250)分别与半金属刹车材料配副的干摩擦磨损性能.结果表明,颗粒体积分数对复合材料摩擦系数的影响显著,而颗粒尺寸对复合材料摩擦系数影响不大.当颗粒体积分数从15%上升到55%时,SiCp(45μm)/Al复合材料的摩擦系数从0.319升高到0.385,提高20.7%,SiCp(63μm)/Al复合材料的摩擦系数从0.303升高到0.359,提高18.5%,且SiCp/Al复合材料摩擦系数的稳定性优于铸铁.HT250-刹车材料摩擦副的磨损率为7.09×10-6cm3m-1,是55%SiCp(45μm)/Al-刹车材料摩擦副的2.2倍,是55%SiCp(63μm)/Al-刹车材料摩擦副的2.7倍,SiCp/Al-刹车材料摩擦副的耐磨性明显优于铸铁-刹车材料摩擦副. SiCp/Al-刹车材料摩擦副的磨损率随着颗粒尺寸的增加而降低.     

工业免维护滑板铁基自润滑材料在不同速度下的摩擦学行为

采用粉末冶金工艺制备了四种不同成分含量的铁基自润滑材料,对材料的微观组织和不同速度下的摩擦学性能进行分析和考察,采用金相显微镜和扫描电子显微镜(SEM)以及X射线衍射仪(XRD)对材料金相、磨痕表面形貌和成分进行表征。结果表明,随着摩擦速度的提高,铁基自润滑材料与40Cr钢盘的摩擦系数呈现降低的趋势,材料中石墨含量越高,速度对其磨损率的影响就越大,在摩擦速度为0.1~0.5m/s的条件下,磨损率达到了10~(-8)cm~3/N·m量级,属于轻微磨损,在1m/s的条件下,Fe-Ni-Mo-C自润滑材料的干摩擦摩擦系数达到了0.27,虽然磨损趋势随速度升高而升高,但与较低石墨含量和不添加石墨的材料相比摩擦磨损性能较优。总体来讲,本文所研制的铁基自润滑材料在不同速度工况下具有较好的摩擦学性能。     

PEEK与纳米TiO_2填充PTFE复合材料的摩擦磨损性能研究

采用高速机械搅拌的方式充分混合原料,然后用模具将混合好的材料冷压成型,再通过一定的烧结程序制备不同体积含量的聚醚醚酮(PEEK)和纳米TiO2协同填充改性的聚四氟乙烯(PTFE)复合材料试样。利用MRH-3摩擦磨损实验机在不同实验条件下对试样进行摩擦学性能的测试。磨损后用QuantaFEG450扫描电镜对钢环表面的摩擦形貌进行观察与分析。实验结果表明,填充PEEK可大幅降低PTFE复合材料的体积磨损率,但复合材料的摩擦系数却随PEEK含量的增加而表现出逐渐上升的趋势。用不同含量的纳米TiO2填充10%PEEK/PTFE,摩擦系数和体积磨损率都表现出随纳米TiO2含量的增加而逐步上升的趋势,其中2%Nana-TiO2/10%PEEK/PTFE复合材料的摩擦系数和体积磨损率最小。当滑动速度和载荷分别超过2m/s和200N后对复合材料的磨损率有显著地影响,而环境温度在25~120℃范围内变化对磨损率和摩擦系数的影响均不明显。     

梯度自润滑复合材料在不同滑动摩擦下的摩擦学特性

梯度自润滑复合材料是一种新型润滑材料,利用粉末冶金工艺设计和制备了该材料,考察了其在不同摩擦条件下的摩擦学特性,并对其摩擦磨损机理进行了分析和研究.结果表明:梯度自润滑复合材料随着复合固体润滑剂含量的增多,摩擦学性能明显改善,但润滑剂含量过高将导致材料表面硬度过低;该材料适用于高载倚下的润滑部件;脂润滑条件下,复合固体润滑剂与润滑脂结合在摩擦面上形成的膏状润滑膜使梯度自润滑复合材料的摩擦学性能显著改善;在脂润滑高载荷条件下,梯度自润滑复合材料的磨损主要发生在磨损初期,之后磨损极小,摩擦系数也趋于减小.     

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.     

Effect of oil and oil with graphite on tribological properties of glass filled PTFE polymer composites

Present work deals with the experimental investigation of tribological properties of GF-filled polymer composites considering three velocities, i.e. 0.5, 1 and 2.0 m/s and loads ranging from 15.7 N to 45.13 N keeping rest of the parameters constant. The test has been carried out for three materials, PTFE + 15% GF, PTFE + 25% GF and PTFE + 35% GF in wet (oil) and adding additive as graphite (5% wt) in oil. SAE 20W40 oil is used for the test. Friction and wear tests of PTFE composite against a counter surface of EN8 with surface finish of 0.56 μm are carried out at ambient conditions using pin-on-disc tribometre (TR-20), Ducom make, Bangalore. The results are tabulated and graphs are plotted. It has been found that load and wet conditions have significant effect on coefficient of friction and specific wear rate of the materials. Where as sliding velocity also plays little role in wear mechanism of the material. It is concluded from the experimental study that the specific wear rate in wet condition as well as by adding additives in lubricating oil with 5% (by wt.) has been declined. Also the specific wear rate decreases with normal load and sliding velocity. Wear of PTFE + GF composite decreases with increase in glass percentage. Microscopic analysis of pin and disc surface is made with optical microscope. The mathematical models has been developed by using regression analysis and found to be valid for the above tested parameters.     

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.     

聚甲醛自润滑复合材料的开发与应用

综述了通过向聚甲醛树脂中添加耐磨聚合物、润滑油及润滑脂，无机润滑剂，纤维材料，金属粉末或薄片，复合润滑剂，以及嵌段共聚，与金属复合改性的方法来制备聚甲醛润滑复合材料，介绍了8类聚甲醛自润滑复合材料的主要性能和应用领域，对聚甲醛自润滑复合材料发展方向及国内聚甲醛复合改性的现状和前景进行了展望。     

Wear behavior of WC<Subscript>P</Subscript>/Fe–C composites under high-speed dry sliding

WC_P/Fe–C composites are manufactured by centrifugal casting method. Dry sliding wear behaviors of the composites containing about 70 vol.% of WC_P were investigated at room temperature against 3Cr2W8V die steel counter face. And wear experiments were performed under loads of 50, 100, 150, and 200 N and sliding velocities of 20, 40, 60, and 80 m/s. Results showed that at the low load of 50 N, the composites, under different sliding velocities, all displayed significantly superior wear resistance. Meanwhile the results also showed that the variation of wear weight loss and wear rate of the composites was almost linear with sliding velocity when the sliding velocity and the load were below 60 m/s and 100 N. But as the sliding velocity and the load exceed 60 m/s and 100 N, the weight loss and wear rate of the composites increased rapidly. But the effect of the load applied on wear weight loss and wear rate was larger than that of the sliding velocity. Finally, the mechanism of the dry sliding wear is discussed in the article.     

Comparative analysis of wear behavior of garnet and fly ash reinforced Al7075 hybrid composite

Al7075 hybrid composites reinforced with varying weight percentage (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%) of each of garnet and fly ash were fabricated and characterized for their comparative wear assessment. The sliding wear test was conducted on a reciprocating tribometer in dry medium under the working conditions of applied normal load (2 N, 4 N, 6 N, 8 N), sliding velocities (0.04 m/s, 0.08 m/s, 0.12 m/s, 0.16 m/s), sliding distance (20 m, 40 m, 60 m, 80 m) and working temperature (25 °C, 50 °C, 75 °C, 100 °C). The experiments were performed as per steady‐state condition and Taguchi (L₂₅) orthogonal array design to evaluate specific wear rate of the Al7075 hybrid composites. The finding of results indicated that the wear rate was decreased with the increase in the filler content in both the case of garnet and fly ash reinforced Al7075 hybrid composites. The results from Taguchi experiments suggested that the filler content and load were the most significant factors affecting wear behavior of composites while temperature and sliding distance are the least significant factors. Also, the garnet reinforced Al7075 hybrid composite indicated less specific wear rate as compared to that of fly ash reinforced Al7075 hybrid composite.     

改性纳米Si_3N_4/环氧树脂复合材料的摩擦磨损特性

研究纳米氮化硅粒子(Si3N4)填充环氧树脂复合材料的滑动干摩擦磨损特性,着重探讨纳米粒子表面接枝共聚改性、粒子含量对复合材料摩擦磨损性能的影响。通过对复合材料磨损表面的粗糙度及形貌分析探讨复合材料的磨损机理。结果表明,纳米氮化硅粒子能在很低的含量下(0.18%(体积分数,下同))显著提高环氧树脂的耐磨性、并降低其摩擦系数,而经过接枝共聚改性的纳米Si3N4粒子填充的复合材料的上述性能改善更为明显,耐磨性比Si3N4/EP提高3倍,摩擦系数降低20%。这说明,在Si3N4纳米粒子表面进行接枝共聚后,有利于加强粒子与基体的界面结合,从而改善复合材料的摩擦学性能。     

水润滑条件下氧化锆颗粒及碳纤维共混增强聚醚醚酮复合材料的摩擦性能研究

通过熔融共混法制备了碳纤维(CF)和氧化锆颗粒(ZrO_2)共混增强聚醚醚酮(PEEK)复合材料,并对其水中的摩擦学性能进行了研究。实验结果表明,该混杂增强复合材料在水中具有优异的摩擦学性能,其摩擦系数随载荷的增加无明显变化,而磨损率则随着载荷的增加而逐渐降低。该材料在水中的磨损机制主要表现为轻微的磨粒磨损和疲劳磨损,碳纤维是复合材料耐磨性得到增强的主要原因,其作为复合材料摩擦面表层的主要承载相,承担了两摩擦面之间的大部分载荷,并保护聚合物基体免于受到对磨副的严重磨损。氧化锆颗粒的加入则有效抑制了摩擦过程中碳纤维的破损与脱落,从而使得混杂增强PEEK复合材料比单纯碳纤维增强的PEEK复合材料具有更加优异的耐磨性能。但过多颗粒的加入会加剧疲劳磨损,从而降低材料的耐磨性。     

AlNP/Al和TiB2P/Al复合材料摩擦磨损性能研究

研究了油润滑条件下两种不同铝基复合材料及其基体合金的摩擦磨损性能,分析了增强体对材料摩擦磨损性能的影响以及相应的磨损机理.结果表明:油润滑条件下,随着摩擦时间的延长,AlNP/Al复合材料的摩擦系数由小变大趋于稳定;而TiB2P/LY12复合材料的摩擦系数却是由大变小趋于稳定,这主要与其摩擦过程中形成凹坑产生润滑油膜有关.由于增强体强度的增加,50%(体积分数,下同)TiB2P/Al复合材料的摩擦系数低于50%AlNP/Al复合材料,且耐磨性优于50%AlNP/LY12复合材料.增强相的加入显著提高了材料的耐磨性,使得复合材料的抗粘着能力明显优于基体合金.