Study on special morphology hydroxyapatite bioactive coating by electrochemical deposition

Bioactive calcium phosphate coatings were deposited on C/C composites using electrochemical deposition technique. The effects of electrolyte concentration and constant current density on morphology, structure and composition of the coating were systematically investigated using SEM, XRD and FTIR spectroscopy. The results show that, the coating weight elevated gradually with the increase of electrolyte concentration, and the morphology of coatings changed from spherical particles to nanolamellar crystals with interlocking structure initially. Then the coating transformed into seaweed-like and nano/micro-sized crystals along the depth direction of the coating. The coatings showed seaweed-like morphology as the deposition current density was less than 20 mA. With the less current density, the coating became more homogenous. However, the coating was flakiness crystal, with need-like crystal stacked upside as the current density reached 20 mA/cm². The coating weight was improved gradually when the current density increased from 2.5 mA/cm² to 10 mA/cm², and then reduced with the increasing current density in the range of 10 to 20 mA/cm².