Synthesis and Characterization of Ag and Cu doped DLC Thin Films for Anti-microbial Applications

Diamond-like carbon (DLC) thin films have garnered significant interest for enhancing the lifespan of biomedical implants due to their excellent mechanical and tribological properties. However, high internal stresses and poor adhesion to metallic substrates limit their application. Metal doping, particularly with silver (Ag) and copper (Cu), has been explored to address these issues due to their inherent antimicrobial property and potential to improve adhesion. In this study, Ag and Cu doped DLC thin films were deposited on biomedical grade CoCrMo alloy discs using DC magnetron sputtering. The concentrations of Ag and Cu in the DLC matrix were controlled by varying the pulsed DC power to the Ag and Cu targets. The films' chemical composition, morphology, and bonding states of the films were evaluated using energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The mechanical, adhesive, physical, and tribological properties of the films were assessed through nano-indentation, optical profilometry, Rockwell C indentation, and pin-on-disk wear testing against ultra-high molecular weight polyethylene (UHMWPE) countersurfaces in a 0.9 wt.% NaCl solution under a 10 N load. The electrochemical corrosion performance was investigated using potentiodynamic polarization tests. The results showed appreciable reduction in residual stress and a slight decrease in hardness with Ag doping up to 13.2 at.% and Cu doping up to 8.1 at.%. However, higher doping levels drastically reduced hardness. Rockwell C indentation tests revealed that Ag and Cu doping enhanced the adhesion of the DLC film to the CoCrMo alloy substrate. Tribological tests show that Ag and Cu doping can reduce the wear rate of the UHMWPE pins, with films containing 7.1 at.% Ag and 11.8 at.% Cu showing the best tribological performance. Furthermore, Potentiodynamic polarization tests showed that the DLC film doped with 7.1 at.% Ag and 8.1 at.% Cu-DLC had the lowest corrosion rates in 0.9 wt.% NaCl solution, much lower than the bare alloy. Antimicrobial testing showed that Ag-DLC films maintained superior antibacterial performance over longer periods compared to Cu-DLC. These results demonstrate the potential of Ag and Cu doped DLC films for artificial joint applications.

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Saskatchewan

Year dc:date.issued

2024

Author dc:creator

• Towobola, Ayowolemiwa Victor

Advisor dc:contributor.advisor

• Yang, Qiaoqin

Committee members dc:contributor.committeemember

• Yang, Qiaoqin
• Oguocha, Ikechukwuka N
• Odeshi, Akindele G

• Diamond-like carbon
• CoCrMo
• Silver
• Copper
• Sputtering
• Adhesion

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/16003

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/16003