Tribological behavior of ionic liquid-based magnetorheological fluids in steel and polymeric point contacts

A range of ionic liquids (ILs)-based magnetorheological (MR) fluids are formulated and their tribological properties investigated in steel-steel, polyoxymethylene-polyoxymethylene POM-POM and polydimethylsiloxane-polydimethylsiloxane PDMS-PDMS point contacts. The effect of particles in dispersion is investigated by measuring neat ILs in the same tribopairs. The boundary lubrication performance of neat ILs is dominated by the Lambda ratio. A correlation is found between the contact angle, wear-scar diameters and friction coefficient. In POM-POM contacts, NTf2− containing ILs do exhibit the largest friction meanwhile full film lubrication occurs in PDMS-PDMS contacts. MR fluid lubricated contacts operate within the boundary regime. However, friction levels are significantly lower than polyalphaolefin PAO based conventional MR fluids. SCN−-based ILs do provide the largest friction coefficients.