Surfactant Influence on Stability and Lubrication Properties of Metal Nanoparticle Suspensions in Oil

Abstract

Typically, only large particles from wear debris can be filtered out from lubricating oils. Ultra-fine particles (usually nano-sized) stay suspended and participate in the lubrication processes as an oil component. Surfactants are important in affecting the behavior of such nanoparticles. This study focuses on suspending pre-fabricated Cu, Fe and Zn nanoparticles in mineral and vegetable oils and observing the influence of surfactants on a number of lubricant properties. Appearance and suspension stability depend on base oil, mechanisms of surfactant action and the nature of the nanoparticles. Oxidation stability is usually jeopardized by metal nanoparticles. Lubricity can be improved by the presence of nanoparticles in case no other additives are used, but nanoparticles may negatively affect the performance of antiwear additives. Nevertheless, some benefits of nanoparticle presence to tribofilm formation can be observed.