TiAl–nHA composite coatings for sintering protection of carbon fiber and improvement of carbon fiber–hydroxyapatite composites interface

To protect carbon fiber (CF) against damage from oxidation during the sintering of CF reinforced hydroxyapatite (HA) composites and improve CF–HA interface, uniform and dense TiAl–nanohydroxyapatite (nHA) coatings were successfully fabricated on the CF surface by combining multiarc ion plating with electrochemical deposition. TiAl–nHA coated CF-reinforced HA (CF/TiAl–nHA/HA) composites were prepared via pressureless sintering. Results show that CF/TiAl–nHA/HA composites present excellent mechanical properties. The fracture toughness can be satisfied with human compact bone. The improved mechanical properties probably benefit from TiAl and nHA coatings. As an oxygen diffusion barrier, TiAl coatings can protect CF against oxidative damage caused by dehydroxylation of HA in the sintering process. The nHA coatings on TiAl-CF can reduce CF–HA interfacial gaps. This study fully utilized the CF enhancement and facilitated the use of CF/HA composites for weight–bearing bone.