Efficient Dispersion of Carbon Nanofibers and Its Impact on the Properties of Paper-based Friction Materials
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 perfor-mance 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.
paper-based friction materialcarbon nanofibreswater system dispersionsthermal conductivityfriction and wear properties
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