Tribochemical wear of silicon nitride against silicate and phosphate glasses

Abstract

Using an environment-controlled ball-on-flat reciprocating tribometer, the effects of water on the wear of Si3N4 were investigated in various environments (dry air, humid air, and liquid water) when rubbing with two kinds of oxide glasses. The experimental results indicated that the wear of Si3N4 was very sensitive to the presence of water and the counter-surface it rubbed against. When rubbing against soda lime glass, the expected mechanical wear of Si3N4 was observed in dry air, and the normal tribochemical wear of Si3N4 occurred in the presence of water (humid air and liquid water). In contrast, when rubbing against phosphate glass, wearless behaviors were observed for Si3N4 surface in all tested environments (dry air, humid air, and liquid water). Moreover, when rubbing against phosphate glass, the abnormal wearless behaviors were also observed for other ceramic materials, such as alumina, zirconia, and silicon carbide. Analyses suggested that poor mechanochemical durability of phosphate glass and the phosphorus-containing compounds in the wear debris were mainly responsible for the wearless behavior of ceramic ball surfaces. Results in present paper could provide insights into the tribochemical wear mechanisms of Si3N4 materials in order to optimize their tribology design.