Corrosion, wear and biocompatibility of hydroxyapatite bio-functionally graded coating on titanium alloy surface prepared by laser cladding

Abstract

A hydroxyapatite (HA) biofunctional gradient coating (BFGC) was prepared on the surface of Ti6Al4V alloy via laser cladding. The effect of the laser power on the properties of the resulting BFGC was evaluated, where the surface morphology and phase distribution of the samples were observed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The wear and corrosion properties of the BFGC samples were studied in simulated body fluid (SBF), and the proliferation of MC3T3-E1 osteoblasts on the surface of the BFGC samples was investigated using an in vitro cell proliferation assay. The surface quality of the BFGC samples initially improved with increasing laser power, where a smooth, dense and crack-free coating surface with a compact interface and tight bonding to the substrate was achieved at 700 W. However, laser powers of 800 W and higher compromised the coating. A strong diffraction peak related to CaTiO3 was observed on the surface of the BFGC samples after laser cladding, while HA deposition was observed on the surface of the coating after immersion in SBF for 30 days. The BFGC samples exhibited excellent wear resistance and corrosion resistance, and were conducive to the proliferation of osteoblasts without cytotoxicity. Overall, this laser cladding BFGC shows promise for enhancing the wear resistance, corrosion resistance and biocompatibility of titanium alloy implants, where the best coating performance was achieved at a laser lap ratio of 50%, scanning speed of 1 cm/s, and laser power of 700 W.