Formation of calcium phosphate coating on carbon fibre with pyrolytic carbon interlayer

Pyrolytic carbon interlayer modified carbon fibers (PCF) were fabricated by chemical vapour deposition method. The original carbon fibers (OCF) and carbon fibers treated by H₂O₂ (HCF) were used as control samples. The CaP coatings were applied on OCF, HCF and PCF using pulse electrochemical deposition (PED) method. The morphology, microstructure and element composition of the CaP coatings for OCF, HCF and PCF were analyzed. The results showed that PCF exhibited smooth surface, whereas OCF and HCF had a grooved surface. More CaP crystals were formed on PCF than those on OCF and HCF using same deposition parameters. The introduction of pyrolytic carbon interlayer resulted in that the CaP coatings on carbon fibers transformed from octacalcium phosphate (OCP) to hydroxyapatite (HA). Simulated body fluid (SBF) immersion behavior of the CaP coating for PCF showed that the CaP coating could induce the formation of new apatite layer and exhibited good in-vitro bioactivity.