COMPOSITION AND PERFORMANCE OF HYDROGENATED CARBON OVERCOATS ON MAGNETIC STORAGE DISKS

Magnetic storage discs overcoated under different conditions with sput tered carbon in the presence of hydrogen were analyzed for hydrogen/ca rbon content by nuclear reaction analysis (NRH:C), for thickness and o ptical absorption by ellipsometry, for carbon structure (D and G bands ) by fast micro-Raman spectrophotometry, and for C-H bonds by polarize d reflection Fourier transform infrared (FTIR) spectrophotometry. CSS wear performances were compared with the analytical data. It was obser ved that wear performance improved with increases of D and G Raman ban d frequencies, DIG Raman intensity ratios, integrated CH2 band intensi ty in the FTIR spectrum, and optical absorptivity, but with decreases of NRAH:C, up to a limiting value. A structural model is proposed to a ccount for the observations. The divergence in the trends of infrared surface C-H and bulk NRAH:C with friction and wear indicates the prese nce of a relatively inert surface coating on a hard amorphous carbon s ubstrate. Representative spectra are shown.