MICROSTRUCTURE AND IN-VITRO TEST BIOACTIVITY BEHAVIOR OF Co-Cr-Mo (F-75)/HYDROXYAPATITE IN PHOSPHATE BUFFERED SALINE SOLUTION

Abstract

Cobalt based alloys were the first metallic materials successfully used in orthopedic applications. However, these alloys are bio-inert, it is necessary to make them bioactive in the human body to improve their application as biomaterials. This research reported the microstructure and in-vitro bioactivity behavior of the novel Co-Cr-Mo alloy (ASTM F-75) filled with different amounts of hydroxyapatite (HAP). F-75 powder was mixed with 2, 6 and 10 wt. % of HAP before being cold compacted at 550 MPa using a uni-axial press machine. The composites then were sintered at 1100°C for 2 h. In-vitro bioactivity behavior of the composites was evaluated by immersing the composites into simulated body fluids for up to 18 days. Results showed that the nucleus of apatite, identified as the apatite layer formed on the surface of the prepared F-75/HAP composite after 18 days of immersion in the phosphate buffered solution (PBS). The Co-Cr-Mo alloy was successfully converted into a bioactive composite by adding 2, 6 and 10 wt. % of HAP particles. It was proposed that the formation of the apatite layer on the surface of F-75/HAP can contribute to the improved biocompatibility and osteoconductivity of F-75/HAP.