Investigation of microstructure, mechanical and biocompatibility properties of CoCrMo matrix carbon nanoparticle reinforced composites produced by powder metallurgy

Despite the exceptional biocompatibility properties of CoCrMo alloys, their poor mechanical properties drive scientists to conduct various studies on CoCrMo alloys. Scientists are investigating the alterations that take place when carbon nanoparticles such as carbon nanotube (CNT), graphene (Gr), and carbon nanofiber (CNF) are introduced to the CoCrMo alloy in order to enhance its strength. They are looking at its microstructure, physical, mechanical, tribological, and biocompatibility properties. Each carbon nanoparticle contained 0.25%, 0.50%, 0.75%, and 1% by weight. Four groups of composite alloys were produced using powder-metallurgy techniques. We analyzed the microstructure using optical, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Additionally, density, mechanical, tribological, and biocompatibility tests were conducted. The microstructure results showed that the carbon nanoparticles were evenly spread throughout the matrix. Grain boundaries were also seen, and carbide phases were found and spread around the grain boundaries. Dendritic structures were also seen in the microstructure. The relative density of the composites decreased as the carbon nanoparticle content increased, ranging from 85.77% to 79.8%. In contrast, Vickers hardness tests revealed a significant increase in hardness with the addition of nanoparticles, with adding 1% Gr achieving the maximum increase in hardness. Tribological tests showed that the wear resistance improved as the amount of carbon nanoparticles increased. The coefficient of friction ranged from 0.48 to 0.63. Again, the alloy containing 1% Gr demonstrated the most favorable tribological properties. Biocompatibility assessment showed improved biocompatibility for all carbon nanoparticle-reinforced alloys compared to the reference alloy (CoCrMo). The findings indicate that including carbon nanoparticles as a reinforcement is promising for developing CoCrMo alloys.