Tribological study of Sialon lubricated by water-based lubricants

The tribological properties of Sialon in air, water and three different sodium solutions were carried out by using SRV ball-on-disk tribo-tester. The tribological test results demonstrate that either under dry sliding or water lubrication, CM-60 shows better anti-wear properties than C-60; water lubrication reduces the friction coefficients of both Sialon ceramics (CM-60 and C-60) but increases their wear volumes. The wear volume order of CM-60 in the three different sodium solutions is as follows: NaNO₃ > Na₃PO₄ >NaH₂PO₂, it indicates that the anti-wear properties of these Na salt solutions are correlated with their oxidation ability; the friction coefficient order of CM-60 in water and three different sodium solutions can be described as: NaNO₃ >H₂O>NaH₂PO₂ >Na₃PO₄. All of these lubricants made the wear surfaces of Sialon ceramics quite smooth. It means that sodium salt solution can be used in chemical polishing of Sialon. Results also show that the reaction between water and the oxides of Sialon has led to corrosion wear of Sialon. Thus, both in water and Na salt solutions, the wear volumes of Sialon ceramics were increased.