Friction and Wear Behaviors of Oxygen‐Charged Zirconium

Zirconium (Zr) and its alloys are promising biomedical implant materials owing to their favorable biocompatibility, corrosion resistance, and low elastic modulus. Nevertheless, Zr faces a dilemma because of the poor wear resistance and low surface hardness. Here, an oxygen‐charging technique to introduce a surface gradient structure for Zr alloys, which includes an oxide film armor layer on the top surface and an oxygen concentration gradient distribution region underneath is exploited. This unique structure exhibits ultrahigh surface hardness and improved wear resistance as compared to its original samples. The 20 μm thick oxide film is composed of columnar m ‐ZrO 2 with a hardness higher than ≈10 GPa. The weight loss of the oxygen‐charged samples is one order of magnitude lower than that of the pure Zr. Notably, the oxygen‐charged Zr‐2.5Nb with layered structures also shows the highest oxide film bonding strength. This findings provide an innovative method for the design of high‐performance biomedical Zr implant materials.