Wear-induced modifications of amorphous carbon in the presence of magnetic media

The effects of wear and annealing on the microstructural features of amorphous carbon thin films were investigated. Amorphous-carbon thin films on hard disks were subjected to wear by full-sized alumina–titanium carbide sliders. The associated microstructural changes were analyzed by high-resolution transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). TEM micrographs and EELS spectra directly showed structural differences between worn and unworn regions, and indicated increased graphitic content. For comparison, unworn amorphous-carbon thin films were annealed and analyzed by near-edge x-ray absorption fine structure spectroscopy. The annealed unworn carbon films also showed structural changes. The microstructural changes at these low temperatures suggest that the metals of the magnetic layers mediate graphitization. This article presents the experiments and proposes a wear mechanism.