Microstructure and mechanical properties of SiC nanowires reinforced hydroxyapatite coating on carbon/carbon composites

In order to improve the cohesion strength of hydroxyapatite (HA) coating on carbon/carbon composites, SiC nanowires were introduced as reinforcement material in the coating. The results showed that the coating reinforced by SiC nanowires consisted of flake-like crystals with non-uniform grain size and plate-like crystals. The flake-like crystals were embedded in the plate-like crystals to form an interlocking structure. The thickness of the coating with SiC naowires was 80 μm, thicker than 25 μm without SiC nanowires. Moreover, in the inner layer of coating, HA crystals distributed uniformly in the SiC nanowires which formed a three-dimensional framework structure. Tensile bond test shows that the average tensile strength of the coatings can be increased from 3.96±0.34 to 8.05±0.41 MPa after introducing SiC nanowires. The porous SiC nanowires could form pinning effect at the coating/matrix interface to improve the interface bond, and provide a three-dimensional framework structure in the deposition process to improve the cohesion of HA coating.