Elemental composition, topography, and wettability of the surface of graphite modified by ion-assisted deposition of chromium coatings

Elemental composition, roughness, and wettability of a graphite surface modified by ion-assisted deposition of a Cr coating ∼300–1000 nm thick are investigated using the methods of Rutherford backscattering, atomic force microscopy, and contact angle measurements. It is established that, in addition to chromium, coatings involve hydrogen, carbon, and oxygen from residual gases of a vacuum chamber because of their incomplete pumping by vacuum pumps and 1–2 at % silicon diffusing from the graphite. It is determined that, as the coating thickness increases, the surface roughness of the modified graphite increases and becomes the predominant factor in increasing its hydrophobicity.