Abstract
In this study, bioactive hydroxyapatite coatings were deposited on commercially pure Grade 2 titanium substrates by detonation spraying at different O₂/C₂H₂ ratios in the range of 2.6-3.7. X-ray diffraction analysis confirmed the predominance of the hydroxyapatite phase with partial formation of α-tricalcium phosphate, which is attributed to high temperatures and intense dynamic processes in the detonation jet. The formed coatings exhibit pronounced hydrophobicity, high structural heterogeneity, and a well-developed surface microrelief, promoting improved interaction with bone tissue and accelerated osseointegration. Tribological tests conducted under dry conditions and in Ringer’s solution demonstrated a significant increase in wear resistance compared to uncoated Grade 2 titanium. The best friction characteristics and the lowest wear volume were observed for coatings deposited at O₂/C₂H₂ ratios of 3.0 and 3.3, which is associated with an optimal combination of crystallinity, phase composition, and adhesion strength. Coatings formed under these conditions provide stable tribological behavior in physiological environments. The obtained results confirm the prospects of detonation-sprayed hydroxyapatite for improving the durability, biocompatibility, and operational reliability of titanium implants.