Adhesion of sol-gel derived hydroxyapatite nanocoatings on anodised pure titanium and titanium (Ti6Al4V) alloy substrates

► Anodised layers on commercially pure (cp) and Ti6Al4V titanium enhance adhesion. ► Hydroxyapatite coatings on anodised Ti6Al4V show better adhesion than cp titanium. ► Anodised layer toughness is higher than the hydroxyapatite coating toughness. ► Anodising treatments improve the adhesive bonding of hydroxyapatite coatings.