Sliding Wear and Self Lubrication Mechanism of Alumina Ceramics at High-Temperatures

Friction and wear of alumina ceramics were conducted in dry sliding from room temperatureto 1200℃. Both friction and wear decreased obviously over 600℃. The friction coefficient at1200℃ was only 60% as that at room temperature. The specific wear rate at 1200℃ decreasedtwo orders of magnitude than that at 600℃, down to 5×10-16m3/(N.m). There are three modelsof wear mechanism in the temperature range. Before 600℃, abrasive wear and development ofmicrocracks are the dominating mechanism. Between 600℃ and 1000℃, a smooth surface layerwith very fine grAlNs, similar to the structure of nano-ceramics, was formed. Plastic deformationand recrystallization controls the friction and wear. At 1200℃, a glassy film occurred on the surfaceby the severe plastic deformation, which makes the friction be in hydro-dynamic lubrication.