Towards near-permanent CoCrMo prosthesis surface by combining micro-texturing and low temperature plasma carburising

Area of Science:

• Biomaterials engineering
• Surface science
• Tribology

Background:

• CoCrMo alloys are widely used for femoral heads in hip implants.
• Surface properties significantly influence the tribological performance and longevity of implants.
• Advanced surface treatments are needed to improve the durability of CoCrMo implants.

Purpose of the Study:

• To develop and evaluate an advanced surface engineering process for CoCrMo femoral heads.
• To investigate the tribological properties of micro-textured CoCrMo after plasma carburising.
• To assess the potential for enhanced biotribological durability and implant lifespan.

Main Methods:

• A duplex surface treatment combining micro-texture with plasma carburising was applied to CoCrMo femoral heads.
• Field Emission Scanning Electron Microscopy (FESEM) and Glow Discharge Optical Emission Spectrometry (GDOES) were used for surface characterization.
• Tribological properties were evaluated using a pendulum hip joint simulator and in-situ colorimetric interferometry.

Main Results:

• A uniform, precipitation-free C S-phase layer with a 10μm case depth was formed across micro-textures.
• Hip simulator tests showed a 20% reduction in friction coefficient for micro-textured surfaces.
• In-situ colorimetric interferometry indicated a maximum film thickness of 530nm, suggesting enhanced lubrication.

Conclusions:

• The duplex surface treatment significantly enhances the biotribological durability of CoCrMo femoral heads.
• The C-supersaturated crystalline microstructure improves long-term tribological performance.
• The enhanced lubrication and reduced friction suggest a potential for exceptional bearing life in hip implants.