بررسي ريزساختار، خواص سايشي، رفتار زيستي و رفتار خوردگي پوششهاي تيتانيم‌نيتريد، تيتانيم‌نايوبيم‌نيتريد و تيتانيم‌سيليكون‌نيتريد اعمال شده بر‌روي‌ايمپلنت‌‌هاي جايگزين كل‌مفصل زانو از جنس آلياژ كبالت-كروم

Total knee arthroplasty is among the most successful orthopedic procedures, but polymer wear an‎d metal-ion release from corrosion limit the clinical lifespan of these implants. In this study, titanium nitride, titanium-niobium nitride, an‎d titanium-silicon nitride coatings (~2 µm thick) were deposited on Co-Cr-Mo alloy substrates by physical vapor deposition (magnetron sputtering), an‎d the effect of atmospheric nitrogen content (15–50%) on the microstructure an‎d mechanical, tribological, corrosion, an‎d biological properties of the coatings was investigated. Nanoindentation results showed that as nitrogen content increased from 15% to 50%, the hardness of the titanium nitride coating decreased from 10.2 to 2.3–2.9 GPa an‎d its elastic modulus decreased from 231 to 142 GPa, while the addition of niobium an‎d silicon increased hardness to 13.7 an‎d 15.0 GPa, respectively (the highest values among all samples); surface roughness remained below 30 nm for all samples. Pin-on-disk testing in simulated body fluid showed a friction coefficient of 0.044 for the uncoated substrate, while titanium nitride coatings ranged from 0.046 to 0.094, with the minimum recorded for the sample deposited at 15% atmospheric nitrogen; the titanium-niobium nitride an‎d titanium-silicon nitride coatings recorded the lowest friction coefficients of all samples (0.034 an‎d 0.036, respectively) an‎d were the only coatings with friction coefficients lower than that of the substrate. Potentiodynamic polarization testing showed that the corrosion current of titanium nitride increased sharply with nitrogen content, from 36.6 nA/cm² at 15% nitrogen to 2549 an‎d 2491 nA/cm² at 30% an‎d 40% nitrogen (attributed to a porous columnar microstructure), whereas the titanium-silicon nitride coating recorded the lowest corrosion current (11.3 nA/cm²) an‎d highest polarization resistance (1.917 MΩ·cm²) among all samples. The substrate showed a corrosion current of 18.4 nA/cm², an‎d the titanium-niobium nitride coating showed intermediate performance with a corrosion current of 35.52 nA/cm². Cytotoxicity testing (MTT) per ISO 10993-5 confirmed that all coatings were non-cytotoxic, with cell viability above 70% (relative to a 100% control; SD <‎ 5%); the titanium-silicon nitride coating showed the highest cell viability among the samples, attributed to its lower contact angle (greater hydro‎philicity). Overall, the titanium-silicon nitride coating — combining the highest hardness (15.0 GPa), lowest friction coefficient (0.036), an‎d lowest corrosion current (11.3 nA/cm²), along with the best biocompatibility — is identified as the most suitable option for improving performance an‎d extending the clinical lifespan of knee implants.

عباس بهرامي , مهدي احمديان

علي اشرفي , عبدالمجيد اسلامي