Structure-Activity Relationship between Two Types of Synthetic Hydrocarbon Base Oils and the Adaptability of Lubricating Additive

Key findings reveal that HBPE exhibits higher branching density and isomerization than PAO4 but inferior thermal and oxidative stability. However, HBPE demonstrates superior tribological properties, including enhanced friction reduction, anti-wear performance, and extreme pressure resistance. Upon DBDTC addition, both lubricants showed improved thermal-oxidative stability and tribological behavior, with PAO4 displaying significantly greater responsiveness: a 38.93% reduction in friction coefficient, 78.15% lower wear rate, and a 163.16% increase in PB value, compared to 15.05%, 44.97%, and 70.88% improvements for HBPE, respectively.

SEM-EDS analysis confirmed the formation of a sulfur- and carbon-rich tribofilm on worn surfaces, indicating that DBDTC's adsorption and tribochemical reactions generate a protective boundary layer. This film effectively minimizes direct asperity contact, thereby enhancing lubrication performance. The distinct response of PAO4 and HBPE to additive incorporation provides valuable insights for formulating high performance lubricants.