Carbon fiber surface-modified by polymer derived ceramic incorporated with graphene to strengthen the mechanical and electrochemical properties of ceramic-carbon fiber composite

In this study, the carbon fiber surface is spray coated with polysilazane preceramic precursor and pyrolyzed at different pyrolytic temperatures to form the ceramic-carbon fiber composite (SiCN-CCFC) with dense layer of amorphous SiCN ceramic film. The specific strength and modulus of SiCN-CCFC are enhanced 44.26% and 15.37% with spraying 40 wt.% polysilazane preceramic precursor diluted in acetone and then pyrolyzing at 450 °C compared with those of the pure carbon fiber. The carbon fiber spray coated with 20 wt% polysilazane preceramic precursor with 0.5 wt.% graphene in acetone is pyrolyzed at 450 °C to form the graphene-reinforced ceramic-carbon fiber composite (SiCN-GRCFC) whose specific strength and modulus are enhanced 73.15% and 41.15%, respectively, compared with those of the pure carbon fiber. The results of potentiodynamic polarization reveal the electrochemical properties between the pure carbon fiber and SiCN-CCFC that the corrosion potential increases from −0.0971 V to 0.5862 V, the corrosion current density decreases from 1.72 × 10−2 to 1.32 × 10−7 mA⋅cm−2, and the corrosion rate extremely decreases from 9.98 × 10−2 to 9.54 × 10−7 mm∙year−1. The electrochemical properties between the pure carbon fiber and SiCN-GRCFC show that the corrosion potential increases from −0.0971 V to 0.5873 V, the corrosion current density decreases from 1.72 × 10−2 to 3.61 × 10−6 mA∙cm−2, and the corrosion rate extremely decreases from 9.98×10−2 to 2.88 × 10−5 mm∙year−1. Therefore, it can be concluded that the SiCN coating incorporated with additional graphene content can significantly enhance the mechanical properties and corrosion resistance of the commercial carbon fiber.