Microstructure and properties of magnetron-sputtered hydroxyapatite/titanium coatings

A series of thin (<10 μm), single-layered HA/Ti coatings were deposited on Ti-6A1-4V substrate using a RF magnetron-assisted sputtering system. Adhesion strength, microstructure and chemistry of the coatings were characterized. Experimental results showed that higher Ti contents in targets/coatings resulted in higher deposition rates. When Ti was added, the highly crystalline structure of monolithic HA coating was largely disrupted and the coating became amorphous-like. The highly crystalline structure of monolithic Ti coating was also disrupted by introducing small amounts of Ca, P and O into the coating. The HA/Ti coatings had quite uniform thicknesses and appeared smooth, dense and well bonded to the substrate. SEM-EDS showed that the Ca/P ratio of HA target was largely retained after sputtering. Adhesion strengths of all coatings were between 60 and 80 MPa.