Diamond-like carbon-deposited films: a new class of biocorrosion protective coatings

Abstract

A series of diamond-like carbon thin films was applied on AISI 316L stainless steel substrates through a pulsed-direct current plasma-enhanced chemical vapor deposition technique to study the effects of working parameters (bias voltage and deposition pressure) on the microstructure and biocorrosion resistance of films. Raman spectra indicated that under low bias voltage and higher deposition pressure, the films possess a higher amount of sp2 structure, lower internal stress and an improved biocorrosion resistance due to a smooth and defect-free morphology. The lamellar sp2 structure blocked a penetration of corrosive entities. The oxygen content of locally corroded areas (∼11·9 wt.%) was much higher than that of non-corroded areas (2·6 wt.%) corroborating galvanic corrosion between carbide and nitride phases. Moreover, by increasing the deposition pressure from 20 to 40 Pa, the internal stress decreased from 1·03 to 0·82 GPa. The results confirmed that it is possible to tailor the properties of the coatings such as structural composition and particularly biocorrosion resistance by the control over the working parameters. Such anticorrosive diamond-like coatings could benefit biomedical implants used for tissue regeneration.