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

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 degrees C and 750 degrees C). Formation of self-lubricating Mo oxides at tribo-interfaces was observed when the temperature increases from 500 degrees C to 750 degrees C. The least friction coefficient (0.34) and specific wear rate of (1.057 x 10-4 mm3/N-m) were observed at 750 degrees 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.

Automated summary

This study investigates the tribological performances of Mo reinforced ZTA ceramics at elevated temperatures. The results show that composites with 15 wt % Mo - ZTA and 10 wt % Mo - ZTA exhibit the lowest friction coefficient and specific wear rate at 750 degrees C, most likely due to the formation of molybdenum-oxide-rich lubricating tribo-films on the worn surface.