In recent years, the use of nanoscale additives to diminish the coefficient of friction and regulate wear mechanisms in engine lubricants has emerged as a growing study field. In this study, the tribological performance of 15W-40 diesel engine oil was investigated by adding four different concentrations (25, 50, 100, and 200 ppm) of dispersed boron carbide (B4C) nanoadditive to 25 mL of oil. Friction and wear tests were performed under limiting lubrication conditions using a tribometer (20 N load, 500 m sliding distance). SEM/EDS analyses were conducted to evaluate the coefficient of friction, wear rate, and surface topography. The results show that the base oil exhibited the lowest average COF (0.112), friction force (2.24 N), and wear loss (0.0055 mm3), whereas the B4C-containing lubricants showed higher average COF (0.129-0.197), friction force (2.58-3.94 N), and wear loss (0.0285-0.0355 mm3) with increasing additive concentration from 25 to 200 ppm. Under the present test conditions, B4C addition did not improve the tribological performance of the base oil; instead, increasing B4C concentration led to progressively higher friction and material loss.
Recep Çağrı Orman (2026) studied this question.