【作者】 王文静；

【导师】 黄剑锋；

【作者基本信息】 陕西科技大学 ， 材料物理与化学， 2014， 博士

【摘要】 近年来，随着汽车产业以及航空工业的迅速发展，摩擦材料领域的研究也发生了急速的增长。纸基摩擦材料作为一类重要的湿式摩擦材料，主要应用于汽车传动系统中的离合器上。如何提高纸基摩擦材料的摩擦系数、摩擦稳定性、耐热性以及耐磨性仍然是目前纸基摩擦材料面临的主要问题。为此，许多学者已经从提高材料中纤维与树脂之间的界面结合与寻找出摩擦性能优异的填料体系两方面入手，展开了研究。本文首先通过添加竹纤维和碳纳米管制备出了界面结合性较好的纸基摩擦材料。研究发现，碳纳米管的加入能够很好地改善材料中纤维和树脂的界面结合性能，从而提高了材料的摩擦性能。当碳纳米管含量为4wt.%时，试样的动摩擦系数达到最大值，为0.1031，此时，试样的摩擦稳定性和耐磨性能也较好。热分析结果显示，试样在加热到1000℃过程中，添加4wt.%碳纳米管的试样的质量损失比未添加碳纳米管的试样减少了10%。扫描电镜测试结果表明，在整个体系中，竹纤维能够很好的附着于碳纤维上，改善了碳纤维和树脂之间的界面结合性能，而碳纳米管优先吸附于竹纤维上，这又保护了竹纤维在摩擦过程中的受热分解，提高了试样的耐热性能。为了更进一步提高材料的摩擦性能，我们在上述体系中分别加入了碳化硅、碳化硼、氧化铝、氧化锆以及硼化锆等填料以及稀土化合物，并研究了填料含量和稀土种类等与试样摩擦性能之间的关系，对不同填料在体系中的作用形式以及试样的摩擦性能进行了初步探讨。结果表明，当试样中含有3wt.%Ce(NO3)3和15wt.%硼化锆时，材料的摩擦性能最佳，材料的动摩擦系数为0.13285，动/静摩擦系数比为0.9010，动摩擦系数在500次摩擦过程中的变异系数为0.75，磨损率为0.6×10-8cm3J-1。最后，研究了以硼化锆为填料、碳纳米管改性碳纤维增强纸基摩擦材料的压缩回弹性能、导热性能、耐热性能以及动态力学性能，并分析了这些性能与试样摩擦性能之间的关系。结果表明，随着硼化锆含量的增加，虽然试样的压缩率和导热系数略有下降，但是，动态力学测试和综合热分析结果表明，含有15wt.%硼化锆的试样具有较高的储能模量和耐热性能。通过材料的组成-储能模量-耐热性-摩擦性能关系的研究，发现体系中储能模量和耐热性能对材料的摩擦性能起关键作用，试样的储能模量越大，制动稳定性越好，耐热性能越好，摩擦稳定性越高，材料的磨损率越低。更多还原

【Abstract】 In recent years, the study of friction material has been obtained rapidgrowth with the development of automotive and aviation industry. Paper-basedfriction materials are mainly used in automotive driveline clutches which workedin lubricating medium. At present, it is still a great challenge that how to improvethe friction coefficient, friction stability, heat resistance and the wear resistanceof paper-based friction material. Therefore, many scholars researched higherperformance of paper-based friction material via two routs; one is improvementof interface bonding between fibers and resin; another one is finding out the fitfiller system to improve the properties of the materials.Firstly, the paper-based friction material, which possess fine interfacialbonding between fibers and phenolic resin, was prepared by adding the bamboofiber and carbon nanotubes into the materials. It is found that carbon nanotubescan effectively improve the friction properties and the combinding capacitybetween fibers and resin of the material. When the carbon nanotubes contentsreached4wt.%, the dynamic friction coefficient of the material is0.1031, andthe sample has good friction stability and wear resistance. Thermal analysisresults showed that the mass loss of the sample with4wt.%carbon nanotubesreduced10%compared to that of sample without carbon nanotubes when thesamples were heated to1000℃.The SEM results showed that, bamboo fiber caneasily attach to the carbon fiber, and carbon nanotubes are easily adsorbed on thesurface of bamboo fiber, which could protect the thermal decomposition of thebamboo fiber during the friction progress and improve the heat resistance of thesample. To further improve the friction properties of the paper-based frictionmaterial, silicon carbide, boron carbide, alumina, zirconium oxide, zirconiumboride, and compound of rare earth were added into the above system,respectively. It is discussed the friction properties and the relationship betweenfiller contents and friction properties of the samples. Results present that whenthe sample contains3wt.%Ce(NO3)3and15wt.%Zirconium boride, the frictionmaterial has the best friction performance, the dynamic friction coefficient of thesample was0.13285, the ratio of the static to dynamic friction coefficient was0.9010, the variation of the dynamic friction coefficient of the sample during500times friction tests was0.75, at then the wear rate of the sample was0.6×10-8cm3J-1.Finally, the compressibility and recovery, thermal properties, heat resistanceand dynamic mechanical analysis of the specimens with different zirconiumboride contents were discussed. Results display that with the increase of thezirconium diboride, the compressibility and thermal conductivity of the sampledecreased slightly. However, the dynamic mechanical test and thermal analysisshowed that the specimen with15wt.%zirconium diboride has a high storagemodulus and good heat resistance. Through studying the relationship betweenthe components, the storage modulus, heat resistance and the friction propertiesof the materials, it can be found that the storage modulus and heat resistance ofthe specimen play an important role in the friction properties of the specimen.The specimen has good braking stability when it has great storage modulus, andit has high friction stability and low wear rate when the specimen has good heatresistance.更多还原