Fabrication of Al2O3–SiCw protective coatings on carbon fiber by the sol-spraying method

Carbon fiber (CF) reinforced hydroxyapatite (HA) composites (CF/HA) are candidate materials for loaded human bones because of their excellent biocompatibility. To prevent the oxidation of CF during sintering process of CF/HA composites, the uniform, dense and continuous Al 2 O 3 coating reinforced by SiC w (Al 2 O 3 –SiC w ) were successfully fabricated via the sol-spraying method. CF was treated by ultrasound-assisted anodic oxidation treatment (CF U2 ) before sol-spraying to obtain good interfacial adhesion between the coatings and CF U2 . The results show that ultrasound-assisted anodic oxidation treatment can significantly increase O-containing functional groups, surface energy, and roughness of CF U2 surface. The oxidation resistance of CF U2 can be significantly improved by Al 2 O 3 –SiC w coatings obtained by three coating times of sol-spraying. The adhesion between Al 2 O 3 –SiC w coatings and CF U2 is strong enough to make 3(Al 2 O 3 –SiC w )/CF U2 satisfy the need of reinforced fibers. The SiC w in Al 2 O 3 –SiC w coatings can prevent the growth of cracks and improve the cohesion of coatings and achieve effective protection. The introduction of Al 2 O 3 –SiC w coatings onto CF U2 surface is an effective way to prevent oxidative damage of CF U2 . When the Al 2 O 3 –SiC w /CF U2 was used to reinforce HA (CF U2 /Al 2 O 3 –SiC w /HA composites), the compressive strength of composites reaches 74.5 MPa, which is almost 2.7 times that of CF/HA. The uniform, dense and continuous Al 2 O 3 coating reinforced by SiC w (Al 2 O 3 –SiC w ) was fabricated via the sol-spraying method. The SiC w in Al 2 O 3 –SiC w coatings can prevent the growth of cracks, improve the cohesion of coatings. Due to effective protection of Al 2 O 3 –SiC w coatings to CF U2 during sintering, compressive strength of the Al 2 O 3 –SiC w /CF U2 reinforced HA composites is almost 2.7 times that of CF/HA. Highlights The Al 2 O 3 –SiC w coatings were prepared on micro-sized CF via the sol-spraying method. CF was treated to obtain good interfacial adhesion between coatings and CF. The oxidation resistance of CF was improved by Al 2 O 3 –SiC w coatings. The possible coating mechanism and protection mechanism of coatings were investigated. Compressive strength of Al 2 O 3 –SiC w coated CF reinforced HA is almost 2.7 times that of CF/HA.