Microstructure and mechanical properties of ultrafine bamboo-shaped SiC rod-reinforced HfC ceramic coating

Ultrafine bamboo-shaped SiC rod-reinforced HfC ceramic coating was fabricated on carbon/carbon (C/C) composites by a simple method, which consists of first fabricating a porous layer with ultrafine bamboo-shaped SiC rods on C/C composites and then depositing HfC ceramic into the porous layer using a two-step chemical vapor deposition technique. The ultrafine bamboo-shaped SiC rods could be well dispersed in the coating, which significantly improved the mechanical properties of the coating and the bonding strength between C/C composites and coating, avoiding the cracking and debonding of the coating. The results showed that the hardness, elastic modulus, and fracture toughness of the coating increased by 21%, 42%, and 106%, respectively, and the bonding strength between C/C composites and coating increased by 30 times due to the incorporation of the ultrafine bamboo-shaped SiC rods. Most interestingly, a novel reinforcing and toughening mechanism is observed that shows the ultrafine bamboo-shaped SiC rods anchoring themselves into the ceramic matrix to effectively transfer load from the matrix to the rods by the mechanical interlocking between the nodes and the surrounding matrix.