Tribological evaluation of calcium-copper-titanate/cerium oxide-based nanolubricants in sliding contact

In the present work, calcium-copper-titanate (approximate to 85nm) and cerium oxide (approximate to 90nm) nanoparticles were blended in paraffin oil (PO) as an additive by varying the concentration from 0.1 to 1.0% w/v, and tribo-performance was evaluated with four-ball tester. The concentration 0.25% w/v of the nanoparticles in PO was found to be optimum in antiwear and antifriction property tests for both types of nanolubricants. At this particular concentration, the maximum reductions in the wear scar diameter were 38.4 and 26.1% for calcium-copper-titanate and cerium oxide-based nanolubricants, respectively. Also, the mean coefficient of friction was reduced by 17.3 and 29.6% at this optimum concentration for both types of lubricants. For extreme-pressure test, the load-carrying capacity of the nanolubricants was improved from 126 to 160kgf as compared with base PO. The worn surfaces were examined with scanning electron microscope, energy-dispersive spectroscopy, and atomic force microscope to study the physical phenomena that occurred during the sliding.