Mechanical properties of hydroxyapatite-zirconia coatings prepared by magnetron sputtering

Hydroxyapatite (HA)-zirconium (ZrO2) composite coating was produced by magnetic sputtering on Ti6Al4V titanium alloy substrate, the coatings of 50HA-50ZrO2 and 75HA-25ZrO2 (mass fraction, %) were characterized by scanning electron microscopy, energy disperse spectroscopy, X-ray diffraction and scratch test, respectively, and the effects of HA contents in the coating on residual stress were analyzed. The experimental results show that the phases of HA-ZrO2 composite coatings are HA, ZrO2 and Y2O3, and the HA has a certain decomposition in the combination process, producing TCP and CaO impurity phases. The porous surface of coating is conducive to the growth of bone tissue, and the surface roughness values of 50HA-50ZrO2 and 75HA-25ZrO2 are 1.61 μm and 2.92 μm, respectively. The coating interface is of mechanical integration, the bonding strength values of 50HA-50ZrO2 and 75HA-25ZrO2 are 30 N and 17.5 N, respectively, showing a downward trend with the HA contents increasing. The residual stress values in the coating of 50HA-50ZrO2 and 75HA-25ZrO2 are (−399.1±3.0) MPa, (−343.2±20.3) MPa, respectively, as a result, the appropriate increase of HA contents in the coating will reduce its residual stress.