Functionally graded carbon nanotubes/hydroxyapatite composite coating by laser cladding

► High-quality metallurgical fusion bonding was obtained between the coatings and substrate, which leaded to strong bonding strength of coating-metal interface. ► The micro-hardness of the functionally graded coating increased gradually through the thickness of this coating. ► The bonding strength of the functionally graded CNTs/HA coating was nearly twice higher than that of pure HA coating. ► The functionally graded composite coating has comparable in vitro bioactivity with pure HA coating.