Surface engineering design of Al2O3/Mo self-lubricating structural ceramics - Part II: Continuous lubrication effects of a three-dimensional lubricating layer at temperatures from 25 to 800 °C

Abstract

Al2O3/Mo self-lubricating structural ceramics with laminated-structure are potential candidates for high-temperature applications because of their excellent self-lubricating and mechanical performances. This study aims at revealing the mechanisms of how a three-dimensional lubricating layer affects the tribological properties of Al2O3/Mo laminated composites at temperatures from 25 to 800°C. A three-dimensional lubricating layer was formed by considering texture pattern as storage dimples and coating solid lubricants (SLs) on the textured surface of Al2O3/Mo laminated composite. The friction properties and wear mechanisms at temperature from 25 to 800°C in a continuous heating process were studied. It is found that the synergy effect of micro-textures and SLs influence the tribological properties of material. Moreover, the tribochemical reaction of SLs stored in the micro-dimples at high temperature improves the lubricating ability of materials, thus realizing continuous lubrication within a wide temperature range. We demonstrated that the friction coefficient of textured surface that coated with MoS2/CaF2–BaF2 SLs was kept lower than 0.50 when subjected to dry sliding wear against Al2O3 ceramic pin at 25–800°C, and it was even lower than 0.15 and 0.35 at 25–200°C and 800°C, respectively. This work is an extension of studies that were previously published in Wear journal.