Microstructure and Micro-Mechanical Properties of Thermally Sprayed HA-TiO₂ Coating on Beta-Titanium Substrate.

Area of Science:

• Biomaterials Science
• Orthopedic Engineering
• Materials Science

Background:

• Metallic implants cause stress-shielding and poor tissue attachment in orthopedic applications.
• Beta-titanium (β-Ti) alloys offer low modulus but lack sufficient biocompatibility.
• Hydroxyapatite (HA) and titanium oxide (TiO2) coatings can enhance implant integration.

Purpose of the Study:

• To develop and characterize a novel HA-TiO2 coating on a β-Ti substrate for orthopedic implants.
• To evaluate the mechanical properties and microstructure of the composite coating.
• To assess the potential of the coating to improve implant performance and reduce stress-shielding.

Main Methods:

• Plasma spray deposition of HA-TiO2 coating onto a β-Ti (Ti-35Nb-7Ta-5Zr) substrate.
• Scanning Electron Microscopy (SEM) for microstructural analysis.
• Transmission Electron Microscopy (TEM) for phase characterization.
• In situ micro-mechanical testing to determine mechanical properties.

Main Results:

• The HA-TiO2 coating exhibited a lamellar structure with amorphous and crystalline phases and some porosity.
• The coating showed lower yield stress (877 ± 174 MPa) and modulus (447 ± 24 MPa) compared to the β-Ti substrate (990 ± 85 MPa yield stress, 259 ± 19 MPa modulus).
• The coating displayed brittle fracture, while the substrate showed plastic deformation.

Conclusions:

• The HA-TiO2 coating on β-Ti offers a promising approach for orthopedic implants by combining the benefits of both materials.
• The coating's porous, bone-like structure may facilitate cell growth and tissue attachment.
• Further research is needed to optimize mechanical properties for enhanced clinical performance.