Table 3: Mechanical characteristics of single-layer HAp coatings and double-layered alumina/hydroxyapatite coatings deposited onTi6Al4V substrates.

Material/ coating types	Thickness [μm]	Adhesion strength [N]	Young’s modulus [GPa]	Vickers hardness, HV [kgf/mm2]
Ti6Al4V			110+10	415+20
Ti6Al4V /Al2O3	2.1+0.2	39.8+2	172+15	953+30
Ti6Al4V/HAp	30.3+0.5	12.7+2	102+10	422+20
Ti6Al4V /Al2O3 /HAp	1.9+0.2/28.4+0.5	35.2+2/8.9+2	151+10	831+30