NUST Institutions Library Catalogue

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.