CoCrMo

CoCrMo refers to a cobalt-chromium-molybdenum alloy used widely in medical devices and dental restorations. The alloy is valued for its high strength, hardness, wear resistance, and corrosion resistance, particularly in applications where articulating surfaces are exposed to body fluids and mechanical loading.

Commercially, CoCrMo alloys for implants consist mainly of cobalt with chromium about 25–30% and molybdenum 5–10%. Trace carbon, nickel, tungsten, and silicon may be present. In orthopedics, implant-grade standards define composition and purity.

Mechanically, CoCrMo exhibits high yield and tensile strengths and hardness, with an elastic modulus around 210–230 GPa, supporting wear resistance. A chromium-oxide surface provides corrosion resistance in body fluids, aiding biocompatibility. Ion release and hypersensitivity can occur in a minority.

Manufacturing uses casting and wrought processing; modern implants often use powder metallurgy with HIP, followed by heat treatment. To reduce wear, components are precisely machined and polished; surface nitride, carbide, or oxide coatings may be applied.

Uses include orthopedic implants such as hip heads, liners, and knee components, where the material interfaces with polyethylene or ceramic counterfaces. Dental applications include crowns, bridges, and some implants, chosen for high strength and fatigue resistance in small, load-bearing parts.

Overall, CoCrMo remains a standard material in load-bearing implants, balancing mechanical performance and biocompatibility, with ongoing research to reduce ion release and improve wear behavior.