Investigation of the tribological properties of engine oil containing hexagonal booron nitride additive

In recent years, the increasing global demand for energy and rising environmental concerns have necessitated the reduction of energy losses and the improvement of system efficiency in internal combustion engines. Among the major sources of energy loss in mechanical systems, friction plays a critical role, as its reduction is essential for lowering fuel consumption and minimizing emissions. In this regard, the addition of nano-sized solid particles to lubricants has become increasingly widespread as a means of enhancing the tribological performance of engine oils. This thesis investigates the effects of adding hexagonal boron nitride (h-BN) nanoparticles, which possess a layered structure and exhibit high thermal and chemical stability, as an additive to engine oil on friction and wear. The h-BN nanoparticles were surface-modified using oleic acid and then homogeneously dispersed into 10W-40 synthetic engine oil at concentrations of 0,25%, 0,50%, 0,75%, and 1,00% using an ultrasonic mixing method. The tribological properties of the engine oils prepared with h-BN addition, particularly their friction and wear behaviors, were evaluated using a test setup based on disk-ball contact. Experimental findings revealed that h-BN-added oils exhibited lower friction and wear values compared to the base oil. Notably, at a concentration of 0.75% h-BN, improvements of approximately 7% in friction and 41% in wear were achieved. Analysis of Stribeck curves indicated that this additive was particularly effective in the mixed lubrication regime, where it formed a lubricating film layer between surfaces, thereby reducing direct contact. These results demonstrate that h-BN nanoparticles have significant potential to enhance the tribological efficiency of engine oils as an additive.