Influence of alkaline species on the high temperature lubrication of molten carbonate

Abstract Ionic liquid with the melting points lower than 100 °C is a promising lubricant used ranging from automotive industry to aerospace application, to reduce the friction consumed energy loss and wear caused failure. This work investigated the high temperature lubrication effect of three different molten alkaline carbonate (high-temperature ionic liquid). The results suggest that the lubrication properties of the alkaline carbonate is alkaline species dependent, the carbonate of potassium shows a better lubrication than sodium and lithium carbonate from 730 to 825 °C. At 920 °C, the alkaline carbonate decomposes and reacts with iron oxide to form an alkali ferrite, the tribo-layer of the reactant shows promising anti-wear, and the Li2Fe3O4 has a better lubricity than NaFeO2 and KFeO2. This study reports the concept of high-temperature ionic liquid lubricant, particularly on the roles of alkaline species. The high-temperature ionic liquid lubricant concept can potentially open up a new direction for the design and application of novel high temperature lubricants.