Nano-Hydroxyapatite Coated Acetabular Cup Implant by Electrophoretic Deposition

A nanostructural hydroxyapatite (HA) coating was deposited to the porous Ti6Al4V acetabular cup implants using a room temperature electrophoretic deposition (EPD) process in order to achieve the improved bonding strength between the implants and cells, fast healing, good corrosion resistance and long-term stability after implantation. The micropores created in the coating will improve the bioactivity and healing processes. In order to let the acetabular cup implant with complicated profile achieve homogeneous HA coating along the high island and low valley regions, a compensation electrode was designed and prepared. The combined EPD with a dip coating processes was able to compensate for the coating profile and led to a homogenous coating on both valley and island areas. The microstructure of the coating was characterized using microscopy. The corrosion property was tested by using electrochemical method. Using this developed coating process can make uniform HA coatings on very complicated implant surfaces. Comparing to the coating made by plasma thermal spray, the EPD HA coating can cover internal pores, and exhibits a better adhesion to the substrate which achieves stronger shear and bond strengths. In addition, electrochemical corrosion test demonstrates that the EPD HA coating possesses a significant improved corrosion resistance compared to the coating prepared using plasma thermal spray HA coating. The success of EPD HA coating to cup implant with porous surface established a basis for enhancing the application of HA coating in orthopedics.