Structure and mechanical properties of carbon coatings formed on an ion-based ethyl cellulose and sulfuric acid underlayer

It was found that irradiating a sublayer based on ethyl cellulose and sulfuric acid with nitrogen ions with energies up to 0.3 keV increases subroughness and reduces the ratio of sp$^3$/sp$^2$-hybridized carbon atoms in the carbon coatings formed on its surface. These structural changes lead to a 1.3–1.6 fold decrease in coating hardness and a 7–12-fold decrease in the volumetric wear coefficient of the counterface, depending on the duration of ion irradiation of the sublayer. Furthermore, coatings with a sublayer treated with nitrogen ions for 4 minutes are characterized by the presence of localized areas with hardness values up to 22.7 GPa and a high average Young’s modulus of 699.3 GPa. According to Raman spectroscopy data, this may be due to the presence of fullerene-like carbon nanostructures or their fragments.