Improving the tribological performances of graphite-like carbon films on Si3N4 and SiC by using Si interlayers

Si interlayers were used to obtain the excellent tribological performances of graphite-like carbon (GLC) film on silicon nitride (Si3N4) and silicon carbide (SiC). The microstructure and mechanical characteristics of the as-prepared GLC films with Si interlayers were investigated by scanning electron microscopy, Raman spectroscopy, nanoindention and scratch test. The tribological behaviors of GLC-coated and uncoated Si3N4 and SiC were comparatively studied by a ball-on-disc tribo-meter in both dry and water environments. Results showed that the Si interlayers were dense and bonded well with both the substrates and GLC layers. The as-prepared GLC films exhibited excellent tribological performances in both dry and water environments. More importantly, the stably mild wear without any delamination was obtained in water by using Si interlayer. The mechanisms of friction reduction and anti-wear performances of GLC films on the two ceramics with Si interlayers under different environmental conditions were discussed, as well as the corresponding models were deduced.

Friction and wear models for the GLC films on Si-based substrate with Si interlayers in: (a) ambient air; (b) water.Highlights► GLC-coated Si3N4 and SiC exhibit low friction and wear in both ambient air and water. ► Dense Si interlayer bonds well with both Si-based substrate and GLC layer. ► Mild wear of GLC on Si3N4 and SiC in water is closely related to the Si interlayers.