Influence of Cu nanofluids on the rolling contact fatigue life of bearing steel

Rolling contact fatigue (RCF) tests were conducted on AISI E-52100 steel balls lubricated with Cu nanofluids prepared using SAE 5 W-40 synthetic oils as base fluids. Functionalized Cu nanoparticles were blended to 0.2% by weight concentration in the base fluids obtained from two different manufacturers. The RCF tests were performed on four ball rolling contact fatigue tester at 75 °C, maximum Hertz stress of 7.37 GPa and a speed of 3000 rpm. The bearing balls tested with Cu nanofluids showed an enhancement of L10 life by 61% as compared to the base fluid. Investigations have also been performed to determine the physicochemical properties of the lubricant blends and their tribo-performance behavior. The tribo-performance of lubricant blends has been investigated using four ball wear tester. The studies have revealed that blending of Cu nanoparticles does not significantly enhance the tribo-performance of blended lubricants. However, the use of nanofluids significantly enhances the fatigue life of the lubricated contacts. The SEM and EDX analysis reveal that the severity of surface damage decreases with the use of nanofluids.