ADHESION OF AMORPHOUS ULTRAFINE CARBON FILMS ON SAPPHIRE: SCRATCH TESTING

Abstract

The research results of the adhesive properties of ultrathin carbon films on sapphire by the sclerometry technique are presented. Both scratch testing parameters and adhesion strength of bond between the amorphous carbon film and sapphire are determined. Adhesion forces have amounted to the value of F₂ = 1.58 mN by the carbon film thickness of h ? 217 nm. The adhesion bond strength of a-C/sapphire couple has amounted to the value of Н₁₂ = 9,48 · 10^−20 J. Thus, the adhesion strength value of carbon film/sapphire has turned out 1.8 times less than, for example, of Au/SiO₂ couple. Scleroscopic tests for the a-C amorphous carbon film on sapphire are performed. Hardness value has amounted to H_SCR = 0.016 hPa which appears far less than hardness of the carbon films obtained by the magnetron sputtering in vacuum. The surface morphology of carbon film scans is investigated by the atomic force microscopy. The carbon film scan roughness is estimated, it amounts to 60 nm.

Keywords

• carbon films, sapphire, adherence of coating, scratch test.