Tribological Performance Analysis of Grey Cast-Iron against 52100 Steel Ball Bearing with Poly-alpha olefin Lubricant with Nano Additives under Reciprocating Motion /

Abstract

This study is based on nano-particle based lubricants and their role in enhancement of tribological performance of base oil. CuO, ZnO and MoS2 nanoparticles are added to PAO-10 in 1wt% concentration along with 2wt.% oleic acid as a dispersant, these three mixtures are then set up for testing with a tribo-pair of ASTM-52100 steel ball and SAEJ431 (G-3000) gray cast iron. The tests are carried out on a computer controlled reciprocating tribometer and all the lubricants are subjected to 10N, 20N and 30N loading conditions. Test duration is 7200 seconds, at 50 rpm and ambient temperature. Under these conditions and a sliding point contact the test rig is designed to test lubricant performance under boundary lubrication regime. To study the wear scar, a digital optical microscope was used and dimensions for each wear scar were recorded along with the surface roughness before and after the testing. The reciprocating tribometer tests were also conducted on SAE-40 and SAE-0W20 fully formulated oils to compare the results with nano-particle based lubricants. The results from the tribometer tests suggest that ZnO nanoparticles showed positive results by slightly improving CoF values and showed a significant reduction in wear volume. CuO nanoparticles showed improvement in CoF values for lower loading conditions but could not improve performance for higher loading conditions. The MoS2 nanoparticles were observed to be most effective in reducing the CoF and wear scar volume when added to PAO-10. The lowest CoF value was observed with PAO+MoS2 at 20N load, which is a 93% improvement as compared to PAO-10. The lowest value for wear scar volume was observed for PAO+MoS2 at 10N load which was 92% improvement as compared with PAO-10 only. This study further discusses the mechanism that physically changes the sliding conditions and play part in reducing the CoF and wear due to presence of nanoparticles and tries to relate them with the results of this study