Investigating the Age-Dependent behavior of MoS₂-hBN nanohybrid additives on the rheological properties of diesel engine oil

This study utilizes Design of Experiment (DOE) to optimize the viscosity of MoS₂-hBN nanolubricants, synthesized using a microwave synthesis platform that significantly reduces synthesis time and energy consumption compared to other methods. The investigation focuses on viscosity and aging characteristics, aiming to understand the relationship between nanolubricant viscosity and key factors: nanoparticle concentration, temperature, and shear rate. The study shows that the optimal concentration of MoS₂-hBN nanoparticles is 0.05 wt%. At this concentration, when subjected to a shear rate of 200 (1/s) and a temperature of 100°C, the highest viscosity recorded is 12.87 mPa·s. In contrast, at 40°C and a shear rate of 50 (1/s), the lowest viscosity measured is 113.42 mPa·s. Experimental validation confirms the accuracy of the model predictions. The study also examines MoS₂-hBN nanolubricant aging behavior under constant high-temperature conditions (100 °C for 120 h), providing insights into its thermal stability, tribological performance, oxidation resistance, and thermal conductivity properties. Compared to SAE20W40 base oil, the nanolubricant reduces friction and wear, forming a protective boundary film to mitigate surface damage. It exhibits enhanced oxidation stability, acting as a free radical scavenger, and improved thermal conductivity due to increased heat transfer efficiency facilitated by nanoparticles. These findings highlight the potential of MoS₂-hBN nanolubricant for high-temperature applications, contributing to enhanced engine performance and durability.