In this study, three oil-soluble phosphonium-based ionic liquids (ILs) were synthesized and then investigated them as potential lubricating additives. The friction-reduction and antiwear performances of the ILs as lubricant additives in pentaerythritol oleate (PETO) and trimethylolpropane trioleate (TMPTO) were evaluated on an Optimol SRV-IV oscillating reciprocating friction and wear tester. The results indicated that tetradecyltrihexylphosphonium O,O′-diethyldithiophosphate (IL3=TTP−DDP) exhibited considerably better lubrication properties than commercially available tricresyl phosphate (TCP) by performing very well at 200 °C. SEM and XPS were performed to analyze the worn surfaces and revealed the fabrication of tribofilm composed of Fe(OH)O, Fe 3 O 4 , FePO 4 and FeSO 4 , which played a crucial role in the excellent lubricating behaviours of the ILs-additived lubricants.
Chemical oil esters synthesized by polyols and fatty acids are biodegradable and have ideal physicochemical and lubricating properties as compared to mineral lubricants. Using sulfuric acid and lipases as catalysts, a polyester lubricant was synthesized from pelargonic acid (PA) and trimethylolpropane (TMP). Lipase-catalyzed goods are superior and more in accordance with green production requirements. The optimized reaction conditions of lipase catalytic were 50 °C, 15%wt enzyme content, PA: TMP= 3.3:1 %, and 15 % water content. When the time reached 96 h, the accumulation of trimethylolpropane (TMPTP) reached 82% under these conditions. The TMPTP purified by molecular distillation has a flashpoint of 276 °C, a pour point of − 57 °C, and a viscosity index of 145, making it more suitable for extreme environments. On this basis, to improve the viscosity-temperature performance of the substrate, a certain proportion of oleic acid (OA) is added. Low viscosity (kinematic viscosity of 4.86–9.54 mm 2 /s at 100 °C), high viscosity index (VI > 160), low pour point (−50 °C), and low friction coefficient (COF) of 0.09 ∼ 0.11 is among the properties of a series of synthetic hetero-chain mixed esters, which can meet the needs of a variety of extremely low temperatures and complex working conditions.
The performance requirements for extreme pressure and anti-wear properties, as well as oxidative stability, are increasingly stringent for MIL-PRF-23699G Enhanced Ester (EE) for aviation turbine engine lubricants. An oligomerization reaction of pentaerythritol through direct esterification using pentaerythritol and dibasic acid catalyzed by tetrabutyl titanate in xylene solvent, was employed to achieve the low-polymerization reaction of dibasic acid and pentaerythritol. A two-step synthesis process yielded a mixed ester comprising dibasic acid pentaerythritol complex ester and pentaerythritol tetrapentanoate. These mixed esters demonstrate excellent viscosity-temperature performance and good oxidative stability, significantly enhancing the extreme load-carrying properties and anti-wear properties of pentaerythritol tetrapentanoate. Molecular dynamics (MD) calculations indicate that complex esters possess higher adsorption energy and molecular interaction energy, enhancing the possibility of ester molecules adsorbing on metal surfaces and producing stronger oil film that can withstand large loads. The novel 5 mm 2 /s pentaerythritol ester containing diacid pentaerythritol complex esters exhibits improved viscosity-temperature performance, high-temperature oxidation resistance, and better tribological properties. Therefore, the novel pentaerythritol esters show potential for application in 5 mm 2 /s EE aircraft engine lubricants.
危险品化学品经营许可证（带存储）