The Tribological Effects of Lubricating Oil Containing Nanometer-Scale Diamond Particles

This dissertation investigates the tribological effects of diamond nanoparticles as a lubricant mineral oil additive. A numerical code was developed that models the sliding contact observed in a standard four-ball test of sliding contact. Four-ball experimental tests were conducted both of neat mineral oil and mineral oil with the diamond nanoparticle additives, varying the trial times, temperatures, nanoparticle concentrations, and loads. The numerical results matched the experimental data remarkably by adjusting the lubricant thermal conductivity to account for the enhanced conductivity of diamond; demonstrating that thermal enhancements are the primary cause of the wear reduction properties of diamond nanoparticle additives.