芳纶在摩擦材料中的应用

本文介绍了芳纶在摩擦材料中的消费量,芳纶浆粕和芳烨粉末在聚四氯乙烯复合材料中的应用。     

芳纶浆粕增强丁腈橡胶复合材料的摩擦磨损性能

利用开炼机制备了丁腈橡胶(NBR)/芳纶浆粕(PPTA-pulp)复合材料。研究了在干摩擦和水润滑条件下,纤维含量、摩擦时间以及载荷对NBR/PPTA-pulp复合材料摩擦磨损性能的影响,并分析了磨损机理。结果表明,芳纶浆粕的加入能够很好地改善复合材料的力学性能和摩擦磨损性能,在相同条件下,当纤维质量分数为20%时,复合材料的综合性能最佳;在干摩擦条件下,随着摩擦时间延长,复合材料的摩擦系数下降,磨耗量增大;随着载荷增加,摩擦系数和磨耗量增大;水润滑条件下,复合材料的摩擦系数和磨耗量较干摩擦大幅度降低且比较稳定,时间和载荷对其影响很小;干摩擦时,复合材料的磨损机理主要为磨粒磨损和疲劳磨损;水润滑时,主要为轻微磨粒磨损。     

改性酚醛树脂摩擦材料研究进展

介绍了用于汽车制动片摩擦材料的常用改性酚醛树脂及其发展,根据国外摩擦材料研究的专利和信息,指出了摩擦材料的研究重点。     

芳纶浆粕型纤维的性能与应用开发

本文综述了芳纶浆粕型纤维（PPTA-pulp）的性能及作为新型增强材料的优点;介绍了其在热固性、热塑性和弹性体复合材料及造纸方面的应用开发动向并指出PPTA-pulp在实际应用中尚待解决的问题。     

一种芳纶浆粕复合材料的制备及其性能研究

通过简单溶剂体系直接缩聚制备了一种芳纶浆粕,其比浓对数黏度为4.42～6.58 dL/g,芳纶浆粕的原纤沿轴向襞裂出许多分支,表面非常粗糙。对石棉、自制Kevlar浆粕、Twaron浆粕及自制的芳纶浆粕增强的酚醛树脂复合材料的热稳定性、力学性能及摩擦性能进行了研究。结果表明:芳纶浆粕在氮气中的热稳定性比空气中稍好且分解速率相对较慢,与Kevlar浆粕在氮气中和空气中的热失重规律一致,芳纶浆粕酚醛树脂复合材料的力学性能优异;与传统纺丝切割法制备的K、T增强的摩擦材料相比,利用简单溶剂体系直接缩聚方法制备的芳纶浆粕增强材料的摩擦系数略低,但高于石棉增强材料的摩擦系数;对比磨损率,自制Kevlar浆粕、Twaron浆粕及自制的芳纶浆粕增强材料均较低,且随着温度的升高,这3种芳纶浆粕增强材料磨损率均呈下降趋势,其磨损性能优于石棉增强的酚醛树脂复合材料,自制芳纶浆粕热稳定性,力学性能及摩擦性能优异,完全可以替代石棉作为增强材料。     

芳纶浆粕纤维增强尼龙材料的结构与性能研究

采用共混的方法制得了芳纶浆粕增强尼龙6复合材料,研究了芳纶浆粕用量及相容剂对增强尼龙6复合材料力学性能的影响,芳纶浆粕对尼龙6结晶行为的影响以及复合材料的形貌进行了研究。结果表明：随芳纶浆粕含量的增加,复合材料的断裂伸长率和缺口冲击强度下降,拉伸断裂强度先降后增;马来酸酐接枝聚丙烯的加入增强了两相界面的结合力,使得应力能够在两相间有效地传递,共混物宏观力学性能较之未加相容剂的尼龙6／芳纶浆粕体系好,其拉伸断裂强度和缺口冲击强度等均有所改善。     

比较芳纶短纤维和芳纶浆粕对绝热材料性能的影响

比较了芳纶短纤维粕(PPTA short-fiber)/三元乙丙橡胶(EPDM)和芳纶浆粕(PPTA pulp)/三元乙丙橡胶的分散性、耐烧蚀性能与力学性能。结果表明,芳纶浆粕比芳纶短纤维在EPDM橡胶中有更好的分散性,芳纶浆粕的拉伸强度和扯断伸长率均优于PPTA short-fiber/EPDM,同时可以得到更高的填充量。芳纶浆粕的最优含量为12.0%,PPTA pulp/EPDM橡胶线烧蚀率为0.064 mm/s,拉伸强度为3.0 MPa,扯断伸长率为210%,具有优异的耐烧蚀性能和力学性能,可以代替芳纶短纤维作为高性能绝热材料而广泛应用。     

芳纶浆粕网络对聚丙烯性能的影响

利用双螺杆挤出机制备了聚丙烯/芳纶浆粕/聚丙烯接枝马来酸酐系列复合材料,采用偏光显微镜和扫描电镜研究了芳纶浆粕在聚丙烯基体中的分散情况,采用动态热机械分析仪、差示扫描量热仪、万能拉伸试验机、维卡软化点测定仪研究了芳纶浆粕用量对聚丙烯复合材料性能的影响。结果表明:芳纶浆粕在聚丙烯基体中形成柔性填料网络,促进聚丙烯异相成核结晶,而且随着芳纶浆粕含量的增加,材料的刚性、强度和韧性以及耐热性能有上升的趋势,但损耗因子有减小的趋势。     

砜芳纶浆粕——非石棉摩阻复合材料中新型增强纤维

本文研究一种新型摩阻材料增强纤维－砜芳纶浆粕，它具有卓越耐高温性能，以砜芳纶浆粕增强摩阻复合材料制品具有稳定摩擦系数和较低磨耗，该纤维在无石棉摩阻材料行业呈良好开发前景。     

PPTA在硫酸中的溶解性能

以硫酸为溶剂溶解聚对苯二甲酰对苯二胺(PPTA),通过热台偏光显微镜观察PPTA的溶解过程,测定溶解过程中PPTA溶液的阻塞系数(k_w)来表征PPTA在硫酸中的溶解性能。结果表明:PPTA在硫酸中先溶胀后溶解,完全溶解后为液晶溶液。随着溶解时间的增加,PPTA溶液的k_w变小,3 h后趋于稳定;随着硫酸浓度的增加以及溶解温度的升高,PPTA溶液的k_w下降;随着PPTA溶液浓度的增加,PPTA溶液的k_w变大。     

Frictional characteristics and vibration behavior of silicone rubber powders modified resin-based friction materials

Resin-based friction materials (RFM) are widely used in vehicle brakes. However, the thermosetting resins and rigid fillers in RFM have low toughness and produce strong vibration behavior during continuous friction processes, which adversely affects the equipment. This work proposed a method for co-blending modification of RFM with silicone rubber powders (SRP) to mitigate friction-induced vibrations, and the mechanism of silicone rubber modification on the vibrational behavior of RFM during friction was investigated. The results demonstrate that SRP-modified RFM exhibit excellent damping property and frictional characteristics. SRP modification improves the stability of the coefficient of friction and reduces fatigue wear. The wear rate of RFM modified with 10 wt% SRP reduced by 29% and the average amplitude of friction-induced vibration decreased by 35.5% compared to unmodified RFM. This work provides both theoretical and practical foundations for designing and developing RFM with high damping, low wear, and low vibration characteristic.     

填充聚丙烯腈复合型浆粕的摩擦/密封复合材料

本文对采用特殊加工工艺使聚丙烯腈浆粕均匀地包覆在聚丙烯腈短切纤维的表面形成的复合型浆粕在摩擦、密封材料中的应用进行了初探。结果发现,复合型浆粕用于摩擦材料中,与树脂基体间的粘合性能优异,材料强度较高,不易剥落,具有较稳定的摩擦磨损性能;用于无石棉密封橡胶板,制得的密封板均匀、有弹性、强度高、耐热。聚丙烯腈复合型浆粕取代石棉或芳纶浆粕用于增强摩擦材料、密封材料等复合材料中,具有优异的综合使用性能和加工性能,具有较高的性价比。     

Friction and wear properties of dumbbell‐shaped jute fiber‐reinforced friction materials

The surfaces of jute fibers (Corchorus capsularis L.) were processed to have different dumbbell‐shaped spacing (5 mm, 10 mm, 15 mm, and 20 mm), and the physical properties of the modified surfaces of the jute fibers were evaluated in this study. The dumbbell‐shaped jute fiber (DJF)‐reinforced friction materials were prepared through compression mold. The friction and wear performance of the DJF were tested using a friction material tester at constant speed. The results showed that the dumbbell‐shaped spacing has less influence on the friction coefficients of friction materials. The friction coefficients of DJF have bigger fluctuation compared with that of straight fiber during the temperature‐increasing procedure. The wear rate of DJF with dumbbell‐shaped spacing of 15 mm was the lowest, except for that when the temperatures were about 200–250°C. Morphologies of wear surfaces of DJF were observed using scanning electron microscopy and the friction characteristics were analyzed. The results showed that reinforced with DJFs in the friction materials can reduce the specific wear rate and the variation in friction coefficient compared with that of straight jute fibers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40748.     

摩擦材料中纤维品种的选择及性能研究

采用干法工艺热压成型,制备混杂纤维增强无石棉摩擦材料,热压温度为165℃,压力为25 MPa,热压时间为500 s,在180℃下热处理120 min。测定材料的摩擦磨损性能、物理性能。结果表明,玻璃纤维混杂增强摩擦材料的摩擦因数在0.33⁰.41之间变化,磨损率为0.28×10-70.41之间变化,磨损率为0.28×10-7⁰.54×10-7cm3/(N·m),洛氏硬度为HRM 76.0,密度为2.18 g/cm3。     

TiN-Ti-DLC等多层复合膜的摩擦学性能研究

在一台УВНИПА 1型双激发源等离子弧薄膜沉积装置上制取TiN Ti DLC、及其含有软金属Cu或PTFE覆盖膜的多层复合涂层。摩擦磨损试验在一台球 盘滑动磨损试验机上进行。结果表明,以TiN和DLC膜为主体的多层复合涂层具有较高的摩擦学特性,过渡金属钛层、软金属和聚四氟乙烯覆盖层可以降低摩擦系数33%～50%,对磨擦表面磨损减少90%。     

Simultaneous enhancement of friction and wear resistance for high-speed braking system with Cr3C2-NiCr-coated brake disk

The current steel brake disk and Cu-based powder metallurgy brake pad used in high-speed trains suffer fading coefficient of friction (COF) and excessive wear, resulting in a shorten lifetime and numerous exhausted brake disks. High-velocity oxygen fuel (HVOF) spray-prepared coatings have proven their ability to improve COF and decrease wear rate. In this article, Cr₃C₂-NiCr coating was sprayed on a steel brake disk, and a series of emergency braking tests under dry and wet conditions were performed on a subscale brake dynamometer, to comprehensively evaluate the braking performance of coated brake disk. The results showed that the coated brake disk exhibits a higher COF at 380 km/h, which effectively inhibits the COF fade compared to the steel brake disk case. The coated brake system also achieves a lower wear rate of the brake pad at 380 km/h, showing the desired high COF and low wear rate properties of the braking system. Additionally, the coated brake disk maintained surface integrity even after severe braking tests, highlighting its potential in the braking system. Based on the characterizations of wear debris and brake pads, a harder and thinner oxide friction film plays a crucial role in achieving the excellent braking performance in coated brake disk cases.     

CF/SiC增强摩阻材料性能研究

采用模压法制备了碳纤维(CF)/碳化硅(SiC)增强摩阻材料,通过摩擦试验研究了CF和SiC质量分数及CF长度对材料摩擦磨损特性的影响。结果表明:随着SiC质量分数的增加,摩擦系数和磨损率都有明显提高,这是由于硬质颗粒的犁沟作用;当CF质量分数<10%时,CF质量分数和长度对摩擦磨损性能影响明显,这归因于CF本身具有良好的自润滑性能以及抗犁削作用。