Accelerated biodegradation and improved mechanical performance of pure iron through surface grain refinement

Area of Science:

• Biomaterials Science
• Materials Engineering
• Surface Engineering

Background:

• Pure iron alloys show promise for temporary medical implants due to biocompatibility and biodegradability.
• Slow degradation rates of pure iron in physiological environments limit its biomedical applications.
• Passive oxide and hydroxide layer formation hinders efficient degradation.

Purpose of the Study:

• To evaluate the effect of severe shot peening on pure iron's performance for biomedical applications.
• To investigate the potential of shot peening to adjust degradation rates.
• To explore grain refinement and surface modification for enhanced implant functionality.

Main Methods:

• Utilized numerical modeling to identify optimal peening parameters for grain refinement.
• Conducted experimental tests to analyze surface structure and interface characteristics.
• Assessed degradation rates in a biologically simulated environment.

Main Results:

• Severe shot peening increased surface roughness, wettability, and surface deformation.
• Significant grain refinement, enhanced surface hardness, and compressive residual stresses were observed.
• Increased surface roughness and microstructural changes promoted faster degradation.

Conclusions:

• Severe shot peening is a scalable surface treatment that enhances pure iron's suitability for biomedical implants.
• The treatment accelerates degradation by modifying surface properties and microstructure.
• This approach broadens the application of pure iron in temporary load-bearing medical devices.