High temperature tribological performance of molybdenum reinforced zirconia toughened alumina composites prepared by pressure-less sintering

Abstract

Molybdenum (Mo) reinforced zirconia-toughened alumina (ZTA) composites are a vital class of self-lubricating ceramics with potential applications as seals, dies and cutting tools. However, their tribological behaviours under elevated temperatures remain largely unexplored. The present study investigates the tribological performances of pressure-less sintered ZTA ceramics containing various weight percentages (0, 5, 10 and 15 wt %) of Mo at elevated temperatures (500 °C and 750 °C). Formation of self-lubricating Mo oxides at tribo-interfaces was observed when the temperature increases from 500 °C to 750 °C. The least friction coefficient (0.34) and specific wear rate of (1.057 × 10−4 mm3/N-m) were observed at 750 °C for 15 wt % Mo – ZTA and 10 wt % Mo – ZTA composites respectively. Phase analysis, and morphological and elemental studies on the wear tracks confirmed the presence of molybdenum-oxide-rich thin lubricating tribo-films on the worn surface, and suggest adhesion as the dominant wear mechanism.