Cobalt Chromium Molybdenum Alloys

(Cobalt Chromium Molybdenum Alloys)

cobalt chromium molybdenum alloys are used in the medical industry for applications such as orthopedic implants. Their popularity has waned due to their limited hardness and tribological properties, leading to the development of alternative systems.

In orthopaedics, cobalt-chromium-molybdenum alloys have been widely used in hip replacements and other metal-on-metal prostheses because of their high strength. However, complications such as loosening and tissue necrosis have been reported. These have been attributed to the alloy’s biocompatibility.

Alloys of this type are manufactured using a range of processing techniques, including casting and wrought forging. Some are fabricated through spark plasma sintering, which results in an alloy with carbide-free microstructures.

The influence of chromium and molybdenum content on the phases present in a cobalt-chromium-molybdenum system is investigated through X-ray diffraction (XRD), nanomechanical, and electrochemical behavior. The results indicate that the hardness of the alloys increases in line with the increasing chromium content, and reduces with increasing molybdenum content.

In addition, the open-circuit potential, polarization resistivity, and linear sweep voltammetry disclose that passivity improves in line with the increasing Cr content, whereas reduced modulus demonstrates an inflection at 30 wt% of Cr. These findings are in agreement with previous research on the metallurgical properties of cobalt-chromium-molybdenum systems.

Cobalt-based alloys possess many desirable properties, such as heat resistance (strong at very high temperatures), wear resistance, and corrosion resistance. They are generally categorized into softer and harder grades, based on the crystallographic nature of cobalt (its sensitivity to stress), the solid-solution-strengthening effects of chromium, tungsten, and molybdenum, the formation of metal carbides, and the corrosion resistance imparted by chromium. The softer and tougher compositions are usually employed in high-temperature applications such as gas turbine vanes and buckets, while the more rigid grades are used to withstand wear and tear.

(Cobalt Chromium Molybdenum Alloys)