【作者】 孙俊杰；

【导师】 马云海；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2012， 硕士

【摘要】 可作为制动摩擦材料增强纤维的主要有玻璃纤维和有机合成纤维，如碳纤维、芳纶纤维等，这些纤维材料性能均一，是较为理想的增强材料。然而它们的原材料石油资源却日益枯竭，同时纤维的制造过程也会消耗大量能源，磨损产物污染环境。而天然纤维来源广泛，可再生，绿色无毒，且产量巨大，天然纤维如果用于增强适当的基体则可以制成完全降解的摩擦材料，这种材料将获得巨大的市场空间。天然纤维具有较高的强度，可以满足力学性能，但是天然纤维也存在与基体相容性差，均一性差及耐高温性能差等问题，采用改性处理以及结构仿生等技术来提高其与基体的结合性，提高摩擦材料的性能，为生物纤维应用拓宽领域。对黄麻纤维进行了改性处理：先对黄麻纤维进行分丝处理，然后将处理好的黄麻纤维充分浸润在1：1配比的甲醇-苯溶液中浸泡24小时，去除一定的淀粉和蜡质。然后对其进行碱处理。用水清洗并浸湿经过预处理的黄麻纤维，然后浸泡在氢氧化钠溶液（改性选用碱溶液浓度为17%）中，浸泡2小时后，用自来水冲洗去除多余碱溶液，再用硫酸（浓度为2%）进行中和，然后放入足量的蒸馏水中，这样处理后可彻底排除酸碱对纤维的影响。最后将黄麻纤维置于140℃电热干燥箱中，热处理3小时。应用仿生螺旋纤维编织机进行螺旋型黄麻纤维的制备，并用WDW-20微机控制电子万能试验机测试不同螺旋升角的断裂载荷，结果表明螺旋纤维断裂负荷随螺旋升角减小先增大后减小，峰值在66°左右。大于66°时纤维受力不均匀，纤维逐根断裂，小于66°时，在同样外拉力作用下，螺旋升角越小纤维受力越大。这个临界值与纤维的摩擦因数，弯曲度，均匀程度等相关。断裂伸长率曲线随螺旋升角的减小呈抛物线状下降趋势。较系统的分析了螺旋纤维含量及螺旋升角对摩擦性能的影响，得出螺旋型黄麻纤维含量在3%，螺旋升角为66°时摩擦因数符合制动要求，并且耐磨性能最为优异。哑铃间距为15mm的哑铃纤维增强摩擦材料磨损率最低,端部粗化处理具有较好的增强效果，磨损率较平直纤维降低很多。对纤维结构进行仿生化处理，有利于提高纤维的增强作用。在低温（200℃以下）下对于黄麻这种与基体界面结合较弱，基体相容性差的短切纤维复合材料具有重要意义，仿生结构处理后的黄麻纤维增强摩擦材料不再像平直纤维那样那么容易在纤维与基体粘结处产生疲劳裂纹。高温（300℃-350℃）下黄麻分解生成的石墨有自清洁和润滑作用，并随着摩擦力作用滑移填充不平整表面，有利于减小黏着磨损；由于减小了黏着磨损，有效防止玻璃纤维裸露及硬质部位的尖锐突出，另外硬质磨粒压入黄麻纤维凹槽处，有利于减小磨粒磨损；由于结构仿生黄麻纤维增强摩擦材料磨削中含有较多石墨，包覆摩擦材料表面，减少摩擦材料与氧气的接触面积，在一定程度上减少了热磨损。黄麻纤维生成石墨具有的这种自清洁和润滑作用对增强摩擦材料的摩擦性能极为有利。更多还原

【Abstract】 Brake friction materials reinforce fiber mainly include glass fiber and organic syntheticfibers such as carbon fiber, aramid fiber, The properties of This fibers are uniform, they areideal reinforcing material. However, the raw material oil resources are depleted, while thefiber manufacturing process will consume a large amount of energy, the product of wear willpollute environment. Natural fibers are renewable, green non-toxic, and have a hugeproduction, natural fiber reinforce appropriate substrate can be made into completelydegraded friction material, this material will have a huge market space. Natural fiber withhigh strength can meet the mechanical properties, but it’s high temperature performance ispoor, modification and structural biomimetic can improve its properties and broaden thefield of bio-fiber applications.The appropriate modification of jute fibers is put jute fiber fully soak in to1:1methanol-benzene solution for24hours to remove some of the starch and wax. Then put in to cleanwater after pretreatment, and then soak it in sodium hydroxide solution (17%) modified theconcentration of alkali solution, soak for2hours, rinse with tap water to remove excessalkali solution, and then put it in to sulfuric acid (2%), and then put it in to sufficient amountof distilled water, this treatment can completely exclude the impact of acid-base. Finally, putjute fiber into electric oven temperature is140°C, heat for3hours.Use biomimetic helical fiber knitting machine spiral fiber into spiral jute fiber. Then useWDW-20microcomputer control electronic universal testing machine to test the fractureload of different helix angle, the results show that the spiral fiber breaking load decreaseswith the helix angle increased and then decreases, the peak at about66°. greater than66°fiber, fiber fracture one by one, when less than66°, face to the same external tensile force,the helix angle the smaller the greater the force of fiber. The threshold effect by fiber frictionfactor, curvature, and uniformity. Elongation with the helix angle decreases downward trend.This paper had a systematic analysis of spiral fiber content and the helix angle effect offriction performance, when the content of spiral jute fiber is3%, and helix angle is66°, thefriction factor can meet the braking requirements, and wear resistance is the mostoutstanding.Dumbbell fiber reinforced friction material who’s dumbbell spacing is15mm have the lowest wear rate.The fiber with Bionic structure will help to improve the enhancement of the fiber. Forjute whose force of combined with substrate interface is weak make great significance at alow temperatures (lower than200°C). Reinforced by the jute with bionic structure frictionmaterial is no longer so easy get fatigue crack between fiber and matrix. under hightemperature (300°C-350°C) Jute decomposition generated Graphite, which have aself-cleaning and self-lubricating effect, with the action of friction slip to fill into unevensurfaces, reduce the adhesive wear and the adhesive wear, effectively prevent bare glassfiber and the rigid prominent parts of the sharp, helps to reduce abrasive wear. Bionic jutefiber reinforced friction materials grinding coating friction material surface can reducefriction material contact with oxygen, reduce the heat wear at a certain extent. The generategraphite which have self-lubrication and self-cleaning effect is extremely beneficial forenhancing the performance of friction material.更多还原