Preparation And Properties Of Carbon Nanotubes Reinforced Fiber-composites

Carbon nanotubes, which have excellent mechanical and electronic properties, are an ideal candidate to fabricate high-performance composite materials, but carbon nanotubes inherently tend to agglomerate and restrict its improvement, therefore. In the study, we prepared the multi-scale reinforce of carbon nanotubes/carbon fiber by the freeze-drying method, and then the composites of continuous carbon fiber/carbon nanotubes/silicon carbide and short carbon fiber/carbon nanotubes/epoxy resin were achieved by the process of vacuum infiltration. The most significant advantage is to achieve homogeneous dispersion of carbon nanotubes in the as-prepared composites and improve the properties of the composites in final.On the basis of the reinforcement of carbon nanotubes/carbon fiber, the composites of carbon nanotubes/carbon fiber/silion carbide were prepared by the process of precursor infiltration and pyrolysis. The prepared one-dimensional carbon nanotubes reinforced composites got a low porosity(<10%), moderate density(1.6g/cm3) and high flexural strength(365MPa), 27% higher than that without carbon nanotubes. The distribution and the contents of carbon nanotubes in the composites can be easily controlled through adjusting the concentration of carbon nanotubes slurry. However, excess carbon nanotubes form dense networks and block up the infiltration channels to organic precursor, and the properties of the prepared composite would decrease. In addition, fast freezing benefits to form well-dispersed carbon nanotubes networks in the multi-scale reinforcement. Moreover, the composites with heat treatment in 1500?C for 1h get better flexural strengths. Nevertheless, because the interfacial bonding strength between T300 carbon fiber and silicon carbide is very high, carbon nanotubes can not improve the properties.Based on reinforcement of carbon nanotubes/short carbon fiber reinforcement, the composites of short carbon nanotubes/carbon fiber/epoxy resin were prepared by the process of vacuum-infiltration and curing. The mechanical and electronic properties of the prepared composites can be adjusted by changing the ratio of short carbon fiber and carbon nanotubes. The properties of the composites are improved with the rise of the content of short carbon fiber when the ratio is relatively small. However, the properties decrease due to excess short carbon fiber destroying the continuity of carbon nanotubes networks when the ratio arrives to 2. Furthermore, the freeze-drying method can be used to prepared multicomponent reinforcement, and we utilize the method to prepare carbon nanotubes/short carbon fiber/silicon carbide ternary reinforcement.