Friction and wear properties of α-AlB12- and SiB6-based ceramics in water

• α-AlB12-based ceramics exhibited friction coefficients lower than 0.2 in water.
• SiB6-based ceramics also exhibited friction coefficients lower than 0.2 in water.
• Both the α-AlB12- and SiB6-based ceramics exhibited high wear resistance in water.
• Both of the boride ceramics exhibited microvickers hardness higher than 20 GPa.

In this study, α-AlB12- and SiB6-based ceramic disk specimens were prepared by spark plasma sintering, and their X-ray diffraction patterns, microstructure, microvickers hardness were examined. Also, the friction and wear properties of the α-AlB12- and SiB6-based ceramic disk specimens were investigated when they were slid against Si3N4, Al2O3 and SiC ball specimens in water. Additionally, the friction and wear properties of the Si3N4–Si3N4 and Al2O3–Al2O3 tribopairs were investigated in water as references. Both the α-AlB12- and SiB6-based ceramic disk specimens exhibited friction coefficients lower than 0.2 when they were slid against the Si3N4, Al2O3 and SiC ball specimens. On the other hand, the Si3N4–Si3N4 and Al2O3–Al2O3 tribopairs exhibited friction coefficients as low as 0.6. The α-AlB12- and SiB6-based ceramic disk specimens and their paired Si3N4, Al2O3 and SiC ball specimens exhibited much lower specific wear rates than the Si3N4–Si3N4 and Al2O3–Al2O3 tribopairs.