Application of Alkylphosphate Ionic Liquids as Lubricants for Ceramic Material

Three kinds of alkylphosphate ionic liquids were synthesized and evaluated as lubricants for silicon nitride–silicon nitride and silicon nitride–zirconium oxide contacts under different test conditions. The results show that silicon nitride substrates exhibit better load-bearing capability compared with zirconium oxide because of their special physical properties and chemical activity. Meanwhile, alkylphosphate ionic liquids exhibit better friction-reducing and antiwear properties than the common ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (L-P104) and the base oil poly(α-olefin) (PAO). Scanning electron microscopy and X-ray photoelectron spectroscopy results indicate that tribochemical reactions occur between the alkylphosphate ionic liquids and ceramic substrates without corrosion during the friction process. When this is combined with the test results for contact angles, it can be concluded that the excellent lubricity of alkylphosphate ionic liquids is ascribed to the synergistic effe...