Comparative Study of Titanium-Doped and Titanium-Silver Co-Doped Diamond-Like Carbon Films

Area of Science:

• Materials Science
• Surface Engineering
• Nanotechnology

Background:

• Diamond-like carbon (DLC) films are known for their excellent tribological and mechanical properties.
• Doping DLC films with metals can further enhance their performance for specific applications.
• Understanding the effects of titanium (Ti) and silver (Ag) codoping on DLC properties is crucial for material design.

Purpose of the Study:

• To investigate the structural, mechanical, and surface properties of Ti-doped and Ti/Ag-codoped DLC films.
• To evaluate the tribological performance and surface energy of these modified DLC films.
• To determine the influence of Ti and Ag codoping on DLC film characteristics.

Main Methods:

• Magnetron sputtering for depositing hydrogen-free DLC, Ti-DLC, and Ti/Ag-DLC films.
• X-ray photoelectron spectroscopy (XPS) for surface composition analysis.
• Atomic force microscopy (AFM) for surface roughness measurements.
• Raman spectroscopy for analyzing sp2/sp3 hybridization.
• Friction and nanoindentation tests for tribological and mechanical evaluation.
• Water contact angle measurements and OWRK calculations for surface wettability and free energy.

Main Results:

• Ti doping and Ti/Ag codoping significantly reduced the coefficient of friction by up to twofold.
• Ti/Ag-DLC films exhibited lower graphitization compared to Ti-DLC films, except at the highest doping levels.
• Surface roughness increased with Ti/Ag codoping, particularly at low concentrations.
• Doping led to a decrease in total surface free energy, driven by reduced dispersive components.
• Hardness loss was most pronounced at the lowest dopant concentrations for both Ti-DLC and Ti/Ag-DLC films.

Conclusions:

• Ti and Ti/Ag codoping of DLC films effectively reduces friction and surface energy.
• Ti/Ag codoping provides a tunable balance of hardness, roughness, and wettability.
• The combination of Ti and Ag offers synergistic benefits, especially at low to moderate concentrations.
• These findings suggest potential for Ti/Ag-DLC films in applications requiring enhanced tribological performance and tailored surface properties.