Fabrication of Zr-Ti-Si glassy metallic overlay on 3D printed Ti-6Al4V implant prototypes for enhanced biocompatibility

Abstract

Implantable materials with enhanced corrosion resistance and bioactivity are highly desired for biomedical application. A 3D metal printed prototype surface was coated with amorphous alloy components of elements Zr, Ti and Si (Zr54Ti35 Si11) as a novel biomedical grade ternary system for the implants. A DC magnetron sputtering technique was used to sputter the films on Ti-6Al-4 V implant prototypes, exhibiting a smooth and denser coating with root means square surface roughness of 1.4 nm. Surface morphology and structural integrity of the thin film metallic glass (TFMG) was studied from electron microscopic techniques and X-ray diffraction analysis. The TFMG is thermally stable with a large supercooled liquid region (∆Tx) of 81.2 °C. Mechanical characteristics of the coatings were studied using the nanoindentation method to correlate the hardness and modulus of the implant materials. Under the simulated body fluid condition, Ti-6Al-4 V implant with 500 nm thickness coatings (Zr54Ti35Si11) exhibited the superior corrosion resistance rate 1 × 10−6 mpy with a charge transfer resistance of 34 kΩ promising for practical application. Electrochemical impedance spectra and Tafel analysis revealed that the corrosion resistance was prominent in the 500 nm thickness TFMG system than the 250 nm and uncoated bare counterparts. The in-vitro biocompatibility and cytotoxicity studies of the as-coated 3D printed implants were studied using the human osteoblast and L929 fibroblast cell lines, respectively. A hemocompatibility study on the implant materials revealed that erythrocytes remain biconcave without aggregation, platelet activation and thrombogenesis, supporting the biocompatibility of the implants. The integration of such unique properties makes these TFMG system ideal candidates for biomedical implants.