Effect of Temperature on the Chemical Composition and Physicochemical Properties of Diester Aviation Lubrication Oil

Abstract

High temperature is the main factor responsible for degrading the lubrication and antiwear properties of aero-lubricating oils. Accordingly, this study assessed the effects of thermal treatment of diester aviation lubricating oil and the associated mechanism. Fourier-transform infrared spectroscopy and gas chromatography/mass spectrometry analyses showed that low-molecular-weight compounds, such as monoesters, diesters, alcohols, and olefins, were the primary degradation products. An assessment of the degradation mechanism of bis(2-ethylhexyl)decanedioate showed that pyrolysis, resulting in the cleavage of β-C–H and C–C bonds, was the main process involved. Additional investigation using advanced polymer chromatography showed that the molecular weights of oil samples changed slightly at high temperatures, while the viscosity and viscosity-temperature index values were relatively stable. High-pressure differential scanning calorimetry established that the thermal oxidation stability of these oils decreased above 250°C. Finally, variations in the chemical compositions of the oil samples were found to be highly correlated with changes in physicochemical properties during thermal processing, with the formation of low-molecular-weight polar compounds greatly increasing the acid numbers of the oils.

Tribological Behavior of Polydiethylsiloxane (PDES) in a Si3N4 and M50 System under Low Temperatures from −80 to 25 °C

“…Specifically, aviation lubricants are subject to exceptionally rigorous conditions, including high temperatures, velocities, and loads, necessitating unparalleled high-temperature performance. These lubricants must also demonstrate a favorable viscosity-temperature relationship and maintain fluidity at low temperatures (below −40 • C) to ensure dependable performance in cold conditions [7][8][9]. Consequently, exploring the low-temperature fluidity alongside the friction and wear characteristics of aerospace lubricants is crucial for enhancing our understanding of aeroengine reliability under such challenging conditions.…”

Properties and tribological evaluation of graphene and fullerene nanoparticles as additives in oil lubrication

“…16 The ability of graphene and fullerene to disperse uniformly in the lubricants has enabled lubrication and anti-wear qualities to degrade mostly because of high temperature. 17 Nonetheless, nanoparticle additives exert different effectiveness in reducing wear in various types of base oils. 18 In addition, the concentration of nanoparticle in base oil has an important role in enhancing tribological properties of base oil.…”

Preparation and performance evaluation of an ester‐bridged antioxidant used as multifunctional additive in ester oil

“…[1][2][3][4] However, with the rapid advancement of equipment, synthetic ester oils fail to satisfy operations demand under increasingly harsh working conditions, especially the high temperature of the lubrication system. 5,6 The high-temperature status inevitably caused rapid thermal oxidation of the synthetic ester oils to form some degradation products and/or polymerised large molecules; consequently, the harmful substances deteriorate their comprehensive performance, resulting in a short service life of the lubricants. [7][8][9] Therefore, exploring a high-efficient antioxidant agent is essential to meet the industrial requirements of synthetic ester oils.…”

“…Owing to their excellent properties such as high thermal‐oxidative stability, low‐temperature fluidity, outstanding viscosity–temperature performance and lubricating properties, synthetic esters have attracted considerable interest 1–4 . However, with the rapid advancement of equipment, synthetic ester oils fail to satisfy operations demand under increasingly harsh working conditions, especially the high temperature of the lubrication system 5,6 . The high‐temperature status inevitably caused rapid thermal oxidation of the synthetic ester oils to form some degradation products and/or polymerised large molecules; consequently, the harmful substances deteriorate their comprehensive performance, resulting in a short service life of the lubricants 7–9 .…”