Investigating biomimetic coatings on Ti-6Al-4V substrates

Abstract

In this in vitro study, medical grade Ti-6Al-4V (Ti64) substrates, approximately 5 mm thick, were immersed in 1.5 × Simulated Body Fluid (SBF) for 56 days to develop biomimetic apatite coatings. Prior to immersion, the substrates underwent surface pretreatment via sandblasting, polishing, and plasma etching. The resulting morphological changes, surface characteristics, crystal structure, phase composition, and mechanical properties were analysed using AFM, SEM, EDS, Micro-CT, and XRD. The findings revealed that surface pretreatment significantly influenced apatite formation. Plasma-etched and sandblasted substrates exhibited more textured and roughened surfaces, which facilitated the formation of denser, more homogeneous coatings compared to the polished substrates. XRD analysis further confirmed the coating to be the hydroxyapatite phase, while AFM measurements demonstrated a notable increase in surface roughness for the sandblasted and plasma-etched samples. Micro CT analysis revealed that while the surface treatments like sandblasting and plasma etching present an interconnected pore structure, the polished surface creates unconnected porosity. These results emphasize the critical role of surface pretreatment in enhancing biomimetic deposition, with implications for improving osseointegration and mechanical compatibility of Ti64-based biomedical implants.

HIGHLIGHTS • Ti-6Al-4V (Ti64) substrates were pretreated by sandblasting, polishing, and plasma etching to alter surface morphology. • Substrates were immersed in 1.5 × Simulated Body Fluid (SBF) in vitro for 56 days to develop biomimetic coatings and assess pretreatment effects. • XRD confirmed hydroxyapatite (HAp) on all samples, and SEM analysis showed rougher surfaces on plasma-etched and sandblasted Ti64. • Sandblasting promoted larger HAp crystallites, improving coating structure and potentional mechanical performance.