Superlubricity and running-in wear maps of water-lubricated dissimilar ceramics

Water-lubricated ceramic sliding tribosystems, when operating under superlubricity conditions, reduce frictional energy losses in many applications. Aqueous superlubricity of 5 dissimilar ceramic tribopairs (Si3N4–Al2O3, Si3N4-ZTA, Si3N4–SiC, Al2O3–SiC, ZrO2–SiC) was thus studied in a series of ball-on-disk tests, with the identification of wear mechanisms and lubrication regimes, while introducing a running-in wear map approach to elucidate transient tribological phenomena. All pairs presented superlubricity for certain combinations of normal load and sliding speed, after a running-in period where mechanical and thermal severities of contact remained mostly below their respective threshold values, promoting mild wear regimes. Load-carrying capacity of ZrO2–SiC was the highest due to high homogeneity and low roughness of the tribofilm on SiC disk’s wear track. •Aqueous superlubricity achieved for three novel combinations ceramic tribopairs.•A running-in wear map approach explains transient tribological behavior of ceramics.•A thin homogenous tribofilm provides high load-bearing capacity to the ZrO2–SiC pair.