Hydroxyapatite coatings on Ti6Al4V and Si(100) Surfaces by Pulsed Laser Deposition*

In this research, the effect of substrate temperature and ablation mechanism on the properties of hydroxyapatite (HA) coatings were investigated. The HA coatings were deposited on Si(100) and Ti6Al4V substrates by pulsed laser deposition (PLD) technique. The key findings of this study were the improvement in bioactive, adherence, and protein adsorption properties as the temperature was increased, but in degradation of all these properties after 700 °C. The depositions were carried out in Ar/H2O and vacuum environments and morpho-structural changes were analyzed using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The adhesion of the coatings to the substrates was evaluated using the pull-out method. The results revealed that increasing temperature led to gradual crystallization of the coatings; however, temperatures exceeding certain temperature had adverse effects on protein adsorption and adhesion properties. Similar patterns were observed in pull-out tests, protein adsorption, and cell proliferation experiments. The ablation mechanism was also found to be a crucial factor in the deposition process. This study highlights the importance of crystallinity in the functionality of the coatings and its dependence on deposition conditions.