Increasing the adhesion forces of hydroxyapatite B, F, and Zr-reinforced coatings

Particularly in the application of biocompatible implant materials, the interfacial and adhesion properties between the coating and the substrate are extremely important. This is due to peeling and deformation of the coating during surgical application. To minimize such negative effects, in this study, titanium substrate was coated with reinforced compounds as a second phase to enhance the mechanical properties of hydroxyapatite. Boron (B), fluorine (F), zirconium, and their combinations were spin-coated onto hydrogen-sputtered titanium substrates by the sol–gel method and sintered at 900°C. The adhesion strength of the coatings was compared with scratch tests. In the results obtained, the highest bond strength was found to be 139.75 and 131 MPa for F/B- and Ca/F-doped HA samples at a 3/1 ratio, respectively. Coatings containing (F) always had a higher bond strength than those without. The critical loads in the scratch tests determine the bond strength of the coating matrix. Instantaneous changes in critical loads alter the coating surfaces, making them very porous and deep, suitable for preferential adhesion by bone-forming osteoblast cells in the body. X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analyses were carried out to study the surface characterization and chemical phenomena of the coated samples.