Toward CoCr Alternatives: Tribo-corrosion performance of interstitially strengthened Cp-Ti surfaces

Orthopedic implants require materials with biocompatibility, corrosion resistance, and wear performance to ensure safety, functionality, and durability. Cobalt-chromium (CoCr) alloys are widely used, but concerns regarding their biocompatibility, ethical sourcing, and regulatory restrictions have prompted interest in alternatives such as commercially pure titanium (Cp-Ti). Titanium has excellent biocompatibility and corrosion resistance but suffers from inadequate wear resistance, which limits its use in load-bearing applications. This study explores the tribo-corrosion behavior of surface-engineered Cp-Ti. The Cp-Ti was surface hardened, employing oxidizing and nitriding treatments followed by vacuum diffusion. These gaseous surface treatments led to interstitially strengthened surface layers, significantly improving hardness and wear resistance. Post-polishing was applied to reduce surface roughness and enhance articulating performance. Results show that oxidizing produced deeper diffusion zones and greater hardness than nitriding. Tribo-corrosion investigations using a ceramic alumina ball as a counterpart proved that surface-hardened titanium could rival CoCr alloys. Consequently, the findings position surface-hardened titanium as a promising alternative to CoCr in biomedical applications.