Study Of The Lubricating Properties Of Steel Lubricants Under Ionic Liquid As A Flow-carrying Condition

In this paper,three imidazolium ionic liquids（[EMIM]BF₄,[BMIM]BF₄ and[OMIM]BF₄）were used as lubricants to select steel-steel friction pairs to investigate the effects of current strength as well as sliding speed and load on tribological properties under ionic liquid lubrication environment;the effects of graphene oxide as an additive on the tribological and corrosion protection properties of the ionic liquids were investigated.（1）The morphology of the abrasion area after lubrication with ionic liquids under current-carrying conditions was observed and the wear volume was measured by means of scanning electron microscopy and a three-dimensional profile tester.It was found that current strengths in a certain range（1-3A）had a positive effect on improving the lubrication performance of ionic liquids,but that current corrosion occurred at a certain strength（4A）,acting as a reverse effect and leading to increased frictional wear.The lubrication mechanism was analysed using XPS and the results showed that complex tribochemical reactions occur in ionic liquids during current-carrying friction and produce a surface protective film consisting of Fe F₂,Fe F₃,Fe（OH）O,Fe₂O₃ and other substances,which is responsible for the significant improvement in friction reduction and anti-wear properties.（2）The influence of the length of alkyl side chains on the lubricating properties of ionic liquids was explored under current-carrying conditions and it was found that the length of alkyl chains had a great influence on the lubricity of charged interfaces.The shorter the alkyl chain length,the more pronounced the coefficient change,while the longer the alkyl chain the stronger the lubricating properties of the ionic liquid.Among them,[EMIM]BF₄ was most affected by the variation of the test parameters,while[OMIM]BF₄ showed the optimum lubricity and corrosion resistance under various test conditions.（3）The effect of GO as an ionic liquid additive on the lubricating properties of ionic liquids was investigated.The effects of concentration,current strength and load on the tribological properties of GO-IL were examined.It was found that:concentration showed a significant effect on lubricity performance,where 0.04 wt%GO-IL showed optimum lubricity and significantly reduced friction and weared on contact surfaces,while concentrations up to 0.2 wt%resulted in coalescence of GO,causing severe wear.In addition,0.04 wt%GO-IL still showed superior performance at high loads,with a coefficient of friction approximately 28%lower and a 24%lower wear volume than pure ionic liquids at the same load conditions.Current-carrying friction experiments were carried out at current intensities of 1 A,2 A and 3 A.It was found that as the current intensity increased,the wear volume gradually increased and the wear level intensified,while GO-IL still showed excellent lubrication performance compared to pure ionic liquids lubrication.