The In-situ Growth Of Surface Coatings On Carbon Fiber And Their Characterization

Extensive attentions have been paid to carbon fibers since their specific mechanic properties, chemical stability, and wide application, and more and more people set to study their surface treatment and modifying recently. Here, we proposed a modified electrochemical method ("electrochemical" method), in which the traditional electrochemical set-up was properly modified, and studied in detail the variation of product on carbon fiber with different parameters based on carbon fibers. Here, the traditional electrochemical electrode and electrolyte were still used, while difference is that these two traditional electrodes were connected by carbon fiber(s), which acted as heating source and substrate which the as-prepared coating can grow in-situ on. Besides, the electrolyte not only can be used as a chemical source and quenching medium, but as an isolation medium to avoid the high temperature oxidation of carbon fibers. This paper mainly focused on the following content:(1) Anatase TiO2 coatings with nanosheet structure were successfully grown in-situ on carbon fibers by our "electrochemical" method. Combined SEM images and Raman spectra results of as-synthesized products, we explored the influences of processing parameters on their morphology and crystallization were mainly discussed, including voltage condition, reaction time, and electrolyte concentration, and optimized the process parameters. The results showed that the increase of corresponding parameters to some extent can promote crystallization, and formation of anatase TiO2 coating.(2) Amorphous SiO2 nanowires can be easily grown in-situ on carbon fiber by our "electrochemical" set-up. We utilized our reaction set-up and synthesized homogeneous nanowires ca.5-10μm in length, and 100 nm in diameter within 10 s, in-situ on carbon fiber. Moreover, we further explored the influences of process parameter on corresponding products, including current intensity, reaction time, electrolyte concentration and pretreatment of ferrous ion, and optimized the process parameters. The as-synthesized amorphous SiO2 nanowires has intensive blue light emission of 403 nm and 465 nm under the excitation of 260 nm.(3) A growth mechanism of SiO2 nanowires on carbon fiber was proposed, based on variation of SiO2 nanowires growth with processing parameters and unique structure of our design. When available voltage is applied, the temperature of carbon fibers will arise sharply, and form a negative temperature filed from inside out. Within this temperature field, carbon fibers are in incandescence, while surrounding electrolyte is at room temperature due to the presence of a large amount of electrolyte, thus huge negative temperature gradient is established, and when it is suitable, the as-pyrolysized SiO2 will further grow in the type of one-dimensional structure on carbon fibers.Obviously, there are many advantages such as low synthetic temperature, non-toxic, easy manipulation, low cost and short reaction time. It can be expected that various oxide can be synthesized in-situ on carbon fiber by adjusting electrolyte constitution, thus, it has a wide application potential in compound coating growth.