Unprecedented laser metal deposition (LMD) biofabrication of nano-ZrO2 reinforced structure-function-integrated Ti–Cu composite: Fabrication, wear, biofunctionality

Abstract

The significance of biomedical applications of Ti alloys is underscored by their widespread utilization as implantable materials. Ti alloy implants are sensitive to fretting wear, which easily leads to early failure. Wear is a major factor in determining the long-term clinical performance. Based on structure-function-integrated concept, this work aims to explore an improved wear-resistant self-antibacterial 3ZrO₂/Ti–3Cu composite using pure Ti powder, Cu powder and nano-ZrO₂ powder via laser metal deposition (LMD). The forming quality, wear performance, and biofunctionality of LMDed 3ZrO₂/Ti–3Cu samples were characterized through specific electron microscopy, mechanical wear tests, and in vitro cell tests. A slightly lower energy density resulted in the best fabrication quality. The spherical morphology of the powders compensated for the different thermodynamic properties of nano-ZrO₂, achieving higher densification. The addition of nano-ZrO₂ into Ti–3Cu refined grains, increased yield strength by 67 % (from 979 MPa to 1637 MPa), microhardness by 62 % (from 291 HV_0.5 to 472 HV_0.5), and Young's modulus by 17 %, maintaining the modulus within the range of human bone. It also reduced wear rate by 36 % (from 0.425 mm³/Nm to 0.366 mm³/Nm) and biocorrosion rate by 32 % (from 3.0 × 10⁻⁸ A/cm² to 1.8 × 10⁻⁸ A/cm²), indicating less corrosion-wear. In addition, LMDed 3ZrO₂/Ti–3Cu showed excellent biocompatibility and bacteriostatic rate >99 % against E. coli. Nano-ZrO₂ enhanced strength, wear and corrosion resistance, while Cu-rich precipitates and Cu ion release provided synergistic antibacterial activity. This work provides a new horizon into the LMD fabrication of improved wear-resistant self-antibacterial structure-function-integrated implant materials.