Tribological evaluation of lubricant additives under boundary lubrication
Growing environmental concern is shifting lubricant markets towards synthetic products, which demonstrate better tribological performance than their mineral oil counterpart. Research on potential economic savings stemming from energy wasted through excessive friction and wear estimates the total global energy consumption could be reduced by 8.7% by 2032. As a byproduct, CO2 emissions stemming from friction and wear deficiencies could be reduced by 35%. The least understood lubrication regime (boundary lubrication) is the major culprit for energy loss, and for this reason, remains a hot topic within a vast interdisciplinary research community. After covering the fundamentals of lubrication, this series of studies explores the lubricant properties of organic and inorganic lubricant additives synthesized for the purpose of mitigating friction and wear under boundary lubrication. First, a biolubricant derived from a novel yeast source is investigated. This is followed by two additional studies which explore the tribological properties of organic additives, specifically synthesized esters and ethers. The synthesized esters and ethers demonstrated drastic reductions in friction and wear compared to commercially available base oil and even outperform two fully formulated engine oils under the reported test conditions. Next, a study on inorganic additives examines the friction and wear behavior of metal nanoparticle composites. Lastly, a study encompassing an analytical approach aimed at characterizing surface evolution for fatigued surfaces is introduced. It demonstrates an effective technique to monitor and predict micropitting failure. For each study, necessary background information and relevant literature is reviewed to provide context. Experimental methods are also included. Spectral data acquired from synthesized lubricants and the scripts describing utilized analytical tools can be found in adjoined appendices.