Influence of Elements on the Corrosion Resistance of DLC Films

Abstract

Pure DLC, Si-DLC, and Si-N-DLC films deposited from C2H2, C2H2 : TMS and C2H2 : TMS : N2 mixtures were used to study the effects of the elemental contents (silicon, silicon-nitrogen) on deposition and corrosion resistance properties. The films were prepared on Si (100) wafers using the plasma-based ion implantation (PBII) technique. The film structure was analyzed using Raman spectroscopy. The composition at the top surface of the films was measured using energy dispersive X-ray spectroscopy (EDS). The hardness and elastic modulus of the films were measured using a nanoindentation hardness tester. The corrosion performance of the films was conducted using potentiodynamic polarization experiments in an aqueous 0.05 M NaCl solution. The results indicate that the hardness and corrosion resistance of the Si-DLC film increase as the silicon content increases. This is due to the increase of the sp3 cluster. The corrosion resistance of a pure DLC film increases when silicon and silicon-nitrogen are doped into the film. Si-DLC films with a silicon content of 40 at.% had a corrosion potential value of 0.61 V, while a Si-N-DLC film with a silicon and nitrogen content of 19.3 at.% and 1 at.% shows a corrosion potential value of 0.85 V, which is a considerable improvement in the corrosion resistance property.