Formation of CaPO<inf>4</inf> and suppression of Ni leaching in nitinol using oxygen and sodium plasma immersion ion implantation

This study investigates the feasibility of apatite formation and the enhancement of Ni corrosion resistance in nitinol using combined sodium and oxygen plasma immersion ion implantation. X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy are used to determine the elemental depth profiles, surface morphology, chemical composition, and reactivity of the specimens. Immersion tests in simulated body fluids and cell cultures, used to assess the bioactivity and cytotoxicity of the plasma implanted samples, show better osteoblast adhesion which indicates enhanced biological performance.