Tribo-Chemical Wear of Amorphous Carbon Overcoats and TiC in Al₂O₃-TiC Sliders

Ambient drag experiments were carried out using $Al2O3-TiC$ sliders and carbon-coated aluminum/magnesium substrate disks. Worn carbon of disks resulted in sub-micron particles that transferred to smears under frictional heating and mechanical shear force. Raman analysis found graphitization for carbon debris and smears but not for carbon within wear tracks. The carbon of wear tracks was also considered graphitized but was very superficial. Decomposition of TiC in DLC-coated and uncoated sliders was also observed and caused by carbon diffusion and titanium oxidation. Diffused carbon could be poly-crystalline graphite and amorphous depending on the reactive environment of the interface. Discussions were made on tribo-chemical wear of the interface materials.