纳米碳纤维的高效分散及其对纸基摩擦材料性能的影响

Efficient Dispersion of Carbon Nanofibers and Its Impact on the Properties of Paper-based Friction Materials

关键词:  纸基摩擦材料  纳米碳纤维  水体系分散性  热性能  摩擦磨损性能

Key Words:paper-based friction material  carbon nanofibres  water system dispersions  thermal conductivity  friction and wear properties

摘要:本研究通过添加表面活性剂并结合超声分散的方式实现了纳米碳纤维（CNFs）在水体系中的稳定分散，探究了分散剂种类及含量、CNFs质量分数、超声条件对分散稳定性的影响。CNFs最佳分散条件为：羧甲基纤维素钠（CMC）质量分数7.5%（相对于CNFs质量），CNFs质量分数0.7%，超声输出振幅强度40%，超声时间20 min。随后将CNFs分散液与增强纤维等原料共混制备湿式纸基摩擦材料，探究了CNFs质量分数对材料表面形貌、孔隙结构、洛氏硬度值、抗张指数、导热性能及摩擦磨损性能的影响。结果表明，添加CNFs可有效消除纸基摩擦材料两面匀度差，增加表面粗糙度。当CNFs质量分数为4%时，相对于未添加CNFs的试样，纸基摩擦材料的法向导热系数提高了8.5%，平面导热系数提高了9.1%；在2.96 MPa压力下平均动摩擦因数提高了20%，有效提高了摩擦因数稳定性；动/静摩擦因数比达0.82，磨损率为0.92×10^-7 m³/(N·m)，较未添加CNFs的样品减少了58%，增强效果最佳。

Abstract:In this study， carbon nanofibres （CNFs）stabilized dispersions were fabricated by combining surfactant and ultrasonic dispersions. The effects of the type and concentrations of the dispersants， CNFs concentration， and the ultrasonic conditions on the dispersion performance was explored. The optimal dispersion conditions of CNFs were as follows： the mass fraction of sodium carboxymethylcellulose （CMC） was 7.5% （relative to CNFs mass）， the mass fraction of CNFs was 0.7%， the ultrasonic output amplitude intensity was 40%， and the ultrasonic time was 20 min. The paper-based friction material was prepared by mixing CNFs dispersion liquid with the raw materials such as reinforced fibers， and the effects of CNFs mass fraction on the surface morphology， pore structure， hardness， tensile index， thermal conductivity， and friction and wear properties of the material were investigated. The results showed that the addition of CNFs could effectively eliminate the evenness difference on both sides of the paper-based friction material and increase the surface roughness. The enhancement effect was optimal when the mass fraction was 4%， increasing the normal thermal conductivity of the material by 8.5% and the planar thermal conductivity by 9.1% compared with the sample without CNFs. At the same time， the friction coefficient stability was effectively improved， with a 20% increase in the average dynamic friction coefficient at 2.96 MPa pressure. The ratio of dynamic/static friction coefficient was 0.82， and the wear rate was 0.92×10^-7 m³/(N·m)， which was reduced by 58% compared with the sample without CNFs.