Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants

Area of Science:

• Biomaterials Science
• Materials Engineering
• Surface Science

Background:

• Nanocrystalline diamond (NCD) coatings offer superior hardness and wear resistance.
• NCD coatings are increasingly explored for biomedical implants due to their tribological properties.
• Ti-6Al-4V alloy is a common material for structural implants.

Purpose of the Study:

• To deposit and evaluate multilayered diamond coatings on Ti-6Al-4V alloy.
• To investigate the impact of alternating nanocrystalline diamond (NCD) and microcrystalline diamond (MCD) layers on coating toughness and adhesion.
• To determine the optimal NCD to MCD thickness ratios and layer numbers for improved performance.

Main Methods:

• Microwave plasma chemical vapor deposition (MPCVD) was used for coating fabrication.
• Coating characterization involved X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM).
• Adhesion was quantified using Rockwell indentation and progressive load scratch tests.

Main Results:

• Multilayered coatings demonstrated adhesion comparable to single-layered NCD coatings.
• The best adhesion was observed in samples with the smallest average grain sizes.
• Higher titanium carbide to diamond ratios correlated with enhanced coating adhesion.

Conclusions:

• Multilayered NCD/MCD coatings are a viable strategy to improve the adhesion and toughness of diamond coatings on Ti-6Al-4V.
• Controlling grain size and the titanium carbide to diamond ratio is crucial for optimizing coating performance.
• These findings support the use of advanced diamond coatings in biomedical implant applications.