Boosting NiTi implant performance with crystalline Ta2O5: Role of deposition rate and post-heat treatment

This study decisively investigates how deposition rate and post-heat treatment impact the performance of tantalum pentoxide coatings on nickel-titanium shape memory alloys using magnetron sputtering. Coatings are deposited at different deposition rates and then vacuum-annealed to induce crystallization and improve the alloy’s superelastic response. A systematic analysis is performed to evaluate microstructure, surface morphology, wettability, adhesion strength, corrosion resistance, radiopacity, and cellular behavior. The findings revealed that a deposition rate of 1.2 Å·s -1 followed by heat treatment yields dense, crack-free orthorhombic Ta 2 O 5 coatings with excellent uniformity and adhesion (critical load 53.9 N). The optimized coating demonstrated increased hydrophilicity (contact angle 62.7˚), improved corrosion protection ( 95.9 %), and complete prevention of Ni ion release. Additionally, the surface facilitated calcium phosphate nucleation (Ca/P 1.64) and supported endothelial cell growth up to 186% compared to the blank untreated cells, confirming strong biocompatibility. Radiographic analysis showed a notable enhancement in X-ray visibility, which is due to higher coating density. Overall, tuning the deposition rate and annealing conditions significantly boosts the durability, biocompatibility, and radiopacity of nickel–titanium implants, positioning crystalline Ta 2 O 5 as a versatile surface coating for advanced biomedical uses.